The catalytic region of DNA polymerase beta is split into three domains. An N-terminal fingers domain, a central palm domain and a C-terminal thumb domain. This entry represents the palm domain [].
The achromobactin synthetase protein D (AcsD) monomer can be decomposed into three domains that resemble a cupped hand (thumb domain 1, palm domain 2 and fingers domain 3). The Domain 1 (thumb) is a three helix bundle flanked by a four stranded anti-parallel β-sheet that forms the dimer interface. Domain 2 bridges domain 1 to domain 3 and comprises a four-helix bundle sandwiched between a three-stranded antiparallel β-sheet and a two-stranded antiparallel β-sheet. Domain 3 is connected to domain 1 by a 31-residue extended loop (L4), it comprises 182 residues folded in a twisted eight-stranded antiparallel β-sheet interspersed with five α-helices and extended loops [].This superfamily represents the helix bundle of the vibrioferrin amide bond forming protein PvsD and achromobactin synthetase protein D (AcsD) palm domain. The secondary structure elements of the palm domain are interspersed with long loops, two of which, L9 and L10, point upwards from the palm and contain three absolutely conserved residues H444, N447 and D464 as well as N509 which is found only in type A and B enzymes [].
DNA is the biological information that instructs cells how to exist in an ordered fashion: accurate replication is thus one of the most important events in the life cycle of a cell. This function is performed by DNA- directed DNA-polymerases ) by adding nucleotide triphosphate (dNTP) residues to the 5'-end of the growing chain of DNA, using a complementary DNA chain as a template. Small RNA molecules are generally used as primers for chain elongation, although terminal proteins may also be used for the de novo synthesis of a DNA chain. Even though there are 2 different methods of priming, these are mediated by 2 very similar polymerases classes, A and B, with similar methods of chain elongation. A number of DNA polymerases have been grouped under the designation of DNA polymerase family B. Six regions of similarity (numbered from I to VI) are found in all or a subset of the B family polymerases. The most conserved region (I) includes a conserved tetrapeptide with two aspartate residues. Its function is not yet known, however, it has been suggested that it may be involved in binding a magnesium ion. All sequences in the B family contain a characteristic DTDS motif, and possess many functional domains, including a 5'-3' elongation domain, a 3'-5' exonuclease domain [], a DNA binding domain, and binding domains for both dNTP's and pyrophosphate []. The DNA polymerase structure resembles a right hand with fingers, palm, and thumb, with an active site formed by a palm holding the catalytic residues, a thumb that binds the primer:template DNA and fingers interacting with incoming nucleotide, and the N and Exo domains extend from the finger toward the thumb [, , ]. This superfamily represents the palm domain of DNA polymerase B composed of 6-stranded β-sheet flanked by two long α-helices from one side and a short helix from the other.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents the "palm"domain of RdRp from Birnavirus. These proteins lack the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain of other RNA-directed RNA polymerases [, ]. The catalytic motifs are arranged in a permuted order, thus, adopting a unique active site topology [].
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This superfamily represents the "palm"domain of RdRp from Birnavirus. These proteins lack the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain of other RNA-directed RNA polymerases [, ]. The catalytic motifs are arranged in a permuted order, thus, adopting a unique active site topology []. This domain adopts and α/β structure.
Prp8 is the largest and most highly conserved spliceosomal protein and is considered a master regulator of the spliceosome. It forms a salt-stable complex with the Brr2 helicase that is required for spliceosome catalytic activation and disassembly, and with the Snu114 GTPase that regulates Brr2 activity. Prp8 consists of a phylogenetically conserved Rnase H fold along with Prp8-specific elements. The function of this domain is to help assemble and stabilise the spliceosomal catalytic core and coordinate the activities of other splicing factors []. The overall structure of Rnase H is reminiscent of a left-hand mitten, in which a central six-stranded mixed β-sheet and the surrounding α-helices of the N-terminal domain correspond to the palm, an extended β-hairpin of the N-terminal domain comprises the thumb and the α-helical C-terminal domain represents the fingers []. This entry represents the palm region of the Rnase H domain which also includes the β-hairpin thumb.
In coronaviruses, papain-like protease (PL(pro)) cleaves the viral replicase polyproteins at different sites releasing non-structural protein NSP1, NSP2, NSP3, and a chymotrypsin-like protease (3CLpro) that cleaves all junctions downstream of NSP4 [].Structurally, coronaviruses papain-like protease consists of a C-terminal catalytic domain containing a right-handed fingers, palm, and thumb domain organisation as well as an N-terminal Ub-like (UBL) domain [, , ].This superfamily represents the palm and finger domains found in papain-like protease from beta and gamma coronaviruses, respectively consisting of 8 and 5 antiparallel β-sheets in MERS-CoV []and 6 and 4 antiparallel β-sheets in SARS-CoV [].
Synonym(s): DNA nucleotidyltransferase (DNA-directed) DNA-directed DNA polymerases() are the key enzymes catalysing the accurate replication of DNA. They require either a small RNA molecule or a protein as a primer for the de novosynthesis of a DNA chain. A number of polymerases belong to this family [, , ].
The catalytic region of DNA polymerase beta is split into three domains. An N-terminal fingers domain, a central palm domain and a C-terminal thumb domain. This entry represents the thumb domain [].
The catalytic region of DNA polymerase beta is split into three domains. An N-terminal fingers domain, a central palm domain and a C-terminal thumb domain. This entry represents the thumb domain superfamily [].
The shape of DNA polymerases can be described as resembling a right hand with thumb, finger, and palm domains. This entry represents the finger domain of the alpha subunit of DNA pol III [, ].
This entry represents the DNA/RNA polymerase superfamily, which includes DNA polymerase I, reverse transcriptase, T7 RNA polymerase, lesion bypass DNA polymerase (Y-family), RNA-dependent RNA-polymerase and dsRNA phage RNA-dependent RNA-polymerase. These enzymes share a similar protein fold at their active site, which resembles the palm subdomain of the right-hand-shaped polymerases [].
The structure of DNA polymerases adopts a shape resembling a right hand with thumb (guides the nascent DNA duplex as it leaves the active site), finger (binds the incoming nucleotide), and palm (active site) domains. This superfamily represents the middle finger subdomain of DNA polymerase III PolC-type [, ].
The Thg1 protein from Saccharomyces cerevisiae is responsible for adding a GMP residue to the 5' end of tRNA His []. The catalytic domain of Thg1 contains a RRM (ferredoxin) fold palm domain, just like the viral RNA-dependent RNA polymerases, reverse transcriptases, family A and B DNA polymerases, adenylyl cyclases, diguanylate cyclases (GGDEF domain) and the predicted polymerase of the CRISPR system []. Thg1 possesses an active site with three acidic residues that chelate Mg++ cations []. Thg1 likely catalyses polymerisation using a similar mechanism to the 5'-3' polymerases [, ].
The catalytic subunit of telomerase is structurally similar to retroviral reverse transcriptases, viral RNA polymerases and, to a lesser extent, the bacteriophage B-family DNA polymerases. Like its structural homologues, the core catalytic subunit of telomerase, TERT, contains the fingers, palm and thumb domains required for nucleic acid and nucleotide associations as well as catalysis. The four major TERT domains: the RNA binding domain (TRBD); the fingers domain, implicated in nucleotide binding and processivity; the palm domain, which contains the active site of the enzyme; and the thumb domain, implicated in DNA binding and processivity are organized into a ring configuration similar to that observed for the substrate-free enzyme. This is the thumb domain found in Tribolium castaneum telomerase catalytic subunit, TERT. Contacts between TERT and the DNA substrate are mostly mediated via backbone interactions with the thumb loop and helix. The thumb helix sits in the minor groove of the RNA-DNA heteroduplex, making extensive contacts with the phosphodiester backbone and the ribose groups of the RNA-DNA hybrid [, ].
Coronaviruses (CoVs) are enveloped positive-strand RNA viruses that infect many species, including humans, other mammals, and birds. After infection, the host may develop respiratory, bowel, liver, and neurological diseases. CoVs are divided into four genera: Alphacoronavirus, Betacoronavirus, Gammacoronavirus, and Deltacoronavirus. SARS, SARS-CoV-2, BatCoV RaTG13 and Bat-SARS-like coronavirus (BATSL-CoVZXC21 and BAT-SL-CoVZC45) belong to the Sarbecovirus subgenus of Betacoronavirus.The CoV replicase gene encodes two overlapping polyproteins, termed pp1a and pp1ab, which mediate viral replication and transcription. The polypeptides pp1a and pp1ab are processed by the action of a main protease (NSP5) and of one or two papain-like proteases (PLpro) found in NSP3 into non-structural proteins (NSPs) to form the replication/transcription complex (RTC). Among them, the NSP12 RNA-dependent RNA polymerase, that includes an RdRp catalytic domain conserved in all RNA viruses, possesses some minimal activity on its own, but the addition of the NSP7 and NSP8 cofactors greatly stimulates polymerase activity. The NSP12-NSP7-NSP8 subcomplex is thus defined as the minimal corecomponent for mediating coronavirus RNA synthesis [, , , , ].The NSP12 subunit contains an N-terminal NiRAN domain, an interface domain and a C-terminal polymerase domain, represented inthis entry, which resembles a right hand, comprising the fingers, palm and thumb subdomains. The active site is located on the palm subdomain and is formed by five conserved NSP12 elements known as motifs A-E [, , , ].
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents the catalytic domain RNA-directed RNA polymerase.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents a RNA-directed RNA polymerase, Phytoreovirus type.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents a RNA-directed RNA polymerase, Orthobunyavirus type.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents a predicted RNA-directed RNA polymerase of Phleboviruses.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents the catalytic domain of the RNA-directed RNA polymerase from all positive-strand RNA eukaryotic viruses with no DNA stage.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents the Reoviridae family of dsRNA viruses.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents the catalytic (palm) domain from the RNA-containing bacteriophage enzymes.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This is a family of Leviviridae RNA replicases.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesisbegins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This superfamily represents a subdomain of the viral RNA-directed RNA polymerase. Its structure consists of 4 α-helices.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses andTospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This group represents a RNA-directed RNA polymerase, Tospovirus type.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents a protein family specific to Tenuivirus, including RNA-directed RNA polymerase L from Rice stripe virus (Pc1), which degrade ssRNA with preference for unstructured ssRNA, but not DNA [].
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This group represents a RNA-directed RNA polymerase, Nairovirus type.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This signature is found in the RNA-direct RNA polymerase of apple chlorotic leaf spot virus and cherry mottle virus.
The RNA polymerase I specific transcription initiation factor Rrn11 is a member of a multiprotein complex essential for the initiation of transcription by RNA polymerase I, together with Rrn6 and Rrn7 subunits [, ]. Binding to the DNA template is dependent on the initial binding of other factors []. Rrn11 contains a tetratricopeptide repeats (TPRs) and interacts with Rrn6 and Rrn7 to form the core factor (CF), which resembles a right hand holding the DNA molecule between the fingers and the palm. The palm is composed of the N-terminal regions of both Rrn11 and Rrn6, the thumb is composed of the C-terminal of Rrn11, and the fingers and knuckles are composed of Rrn7 and the C-terminal half of Rrn6, respectively [].
The RNA polymerase I specific transcription initiation factor Rrn11 is a member of a multiprotein complex essential for the initiation of transcription by RNA polymerase I, together with Rrn6 and Rrn7 subunits [, ]. Binding to the DNA template is dependent on the initial binding of other factors []. Rrn11 contains a tetratricopeptide repeats (TPRs) and interacts with Rrn6 and Rrn7 to form the core factor (CF), which resembles a right hand holding the DNA molecule between the fingers and the palm. The palm is composed of the N-terminal regions of both Rrn11 and Rrn6, the thumb is composed of the C-terminal of Rrn11, and the fingers and knuckles are composed of Rrn7 and the C-terminal half of Rrn6, respectively [].
The sequences in this family are similar to the reoviral minor core protein lambda 3 (), which functions as a RNA-dependent RNA polymerase within the protein capsid. It is organised into 3 domains. The N- and C-terminal domains create a "cage"which encloses a conserved central catalytic domain within a hollow centre. This catalytic domain is arranged to form finger, palm and thumb subdomains. Unlike other RNA polymerases, such as HIV reverse transcriptase and T7 RNA polymerase, the lambda 3 protein binds template and substrate with only localised rearrangements, and catalytic activity can occur with little structural change. However, the structure of the catalytic complex is similar to that of other polymerase catalytic complexes with known structure [].
RNA-directed RNA Polymerase corresponds to the nonstructural protein 12 (NSP12) produced by cleavage of OFR1b. NSP12 contains a polymerase domain that assumes a structure resembling a cupped 'right hand', similar to other polymerases, containing a fingers domain, a palm domain and a thumb domain. Coronavirus NSP12 also contains a nidovirus-unique N-terminal extension (nidovirus RdRp-associated nucleotidyltransferase (NiRAN)) that possesses a kinase-like fold allowing the binding of NSP12 to NSP7 and NSP8. NSP12 possesses some minimal activity on its own, but the addition of the NSP7 and NSP8 co-factors greatly stimulates polymerase activity [, , , ].This domain represents the N-terminal region of the coronavirus RNA-directed RNA Polymerase, which includes the NiRAN and interface domains [, ]. The function of the NiRAN domain is not clear and its target is yet unknown, but it has enzymatic activity that is essential for viral propagation. Structure from SARS-CoV-2 revealed that this domain binds ADP-Mg+2, which may constitute a new pocket for anti-viral treatment development [].
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents the thumb domain of RdRp from Birnavirus, which contain the conserved RdRp motifs that reside in the catalytic "palm"domain () of all classes of polymerases but in a characteristic permuted order, thus, it adopts a unique active site topology [, ]. Additionally, the birnavirus RdRps lack the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain of other RdRps [, , ].
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents the C-terminal domain of RdRp from Birnavirus, which lack the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain () of other RdRps []. These enzymes have the five essential RNA polymerase motifs in a permuted order of C-A-B-D-E to form a conserved catalytic active site [, ]. This domain is mostly α-helical and runs across the canyon in the front of the palm, wrapping around the fingers subdomain [], which may function to prevent back-primed RNA synthesis during protein priming.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents the C-terminal domain of RdRp from avibirnaviruses, which lack the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain () of other RdRps []. These enzymes have the five essential RNA polymerase motifs in a permuted order of C-A-B-D-E to form a conserved catalytic active site [, ]. This domain is mostly α-helical and runs across the canyon in the front of the palm, wrapping around the fingers subdomain [], which may function to prevent back-primed RNA synthesis during protein priming. This domain adopts an α-helical orthogonal bundle structure.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents the thumb domain of RdRp from Birnavirus, which contain the conserved RdRp motifs that reside in the catalytic "palm"domain () of all classes of polymerases but in a characteristic permuted order, thus, it adopts a unique active site topology [, ]. Additionally, the birnavirus RdRps lack the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain of other RdRps [, , ]. This domain adopts an α-helical bundle arrangement.
This entry represents the C-terminal domain of the RNA-directed RNA polymerase (RdRp) found in many positive strand RNA eukaryotic viruses. It is part of the genome polyprotein that contains other polypeptides such as coat proteins VP1 to VP4, core proteins P2A to P2C and P3A, genome-linked protein VPG and picornain 3C ().Structural studies indicate that these proteins form the "right hand"structure found in all oligonucleotide polymerases, containing thumb, finger and palm domains, and also the additional bridging finger and thumb domains unique to RNA-directed RNA polymerases [, , , ].Remdesivir, a recent treatment approved for Covid-19 disease, directly interacts with this region of the RdRp (NSP12) from SARS-CoV-2 and explains its mechanism of action via delayed-chain termination [].
Thg1 was originally characterised as synthesising the guanine nucleotide at the -1 position of the histidinyl tRNA (HtRNA). Thg1 has also been shown to have polymerase activity, which has been proposed to be the ancestral activity of this enzyme [, ]. Thg1 polymerases contain an additional region of conservation C-terminal to the core palm domain that comprise of 5 helices and two strands []. This region has several well-conserved charged residues including a basic residue found towards the end of the first helix of this unit might contribute to the Thg1-specific active site []. This C-terminal module of Thg1 is predicted to form a helical bundle that functions equivalently to the fingers of the other nucleic acid polymerases, probably in interacting with the template HtRNA [].
The achromobactin synthetase protein D (AcsD) monomer can be decomposed into three domains that resemble a cupped hand (thumb domain 1, palm domain 2 and fingers domain 3). The Domain 1 (thumb) is a three helix bundle flanked by a four stranded anti-parallel β-sheet that forms the dimer interface. Domain 2 bridges domain 1 to domain 3 and comprises a four-helix bundle sandwiched between a three-stranded antiparallel β-sheet and a two-stranded antiparallel β-sheet. Domain 3 is connected to domain 1 by a 31-residue extended loop (L4), it comprises 182 residues folded in a twisted eight-stranded antiparallel β-sheet interspersed with five α-helices and extended loops [].This superfamily represents the four stranded β-sheet of the vibrioferrin amide bond forming protein PvsD, AcsD and related proteins, thumb domain.
The achromobactin synthetase protein D (AcsD) monomer can be decomposed into three domains that resemble a cupped hand (thumb domain 1, palm domain 2 and fingers domain 3). The Domain 1 (thumb) is a three helix bundle flanked by a four stranded anti-parallel β-sheet that forms the dimer interface. Domain 2 bridges domain 1 to domain 3 and comprises a four-helix bundle sandwiched between a three-stranded antiparallel β-sheet and a two-stranded antiparallel β-sheet. Domain 3 is connected to domain 1 by a 31-residue extended loop (L4), it comprises 182 residues folded in a twisted eight-stranded antiparallel β-sheet interspersed with five α-helices and extended loops [].This superfamily represents the helix bundle of the vibrioferrin amide bond forming protein PvsD, AcsD and related proteins, thumb domain.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents RNA-directed RNA polymerase (also known as the large structural protein) from Mononegavirales including Paramyxoviruses []. The large structural protein (or L protein) carries four enzymatic activities: RNA-directed RNA polymerase (), mRNA (guanine-N(7)-)-methyltransferase (), mRNA guanylyltransferase (), and poly(A) synthetase. The viral mRNA guanylyl transferase displays a different biochemical reaction than the cellular enzyme. The template is composed of the viral RNA tightly encapsidated by the nucleoprotein (N). The protein can function either as transcriptase or as replicase. The transcriptase synthesises subsequently subgenomic RNAs, assuring their capping and polyadenylation by a stuttering mechanism. The transcriptase stutters on a specific sequence, resulting on a cotranscriptional editing of the phosphoprotein (P) mRNA. The replicase mode is dependent on intracellular N protein concentration. In this mode, the polymerase replicates the whole viral genome without recognizing the transcriptional signals. 5' GpppApGpG sequence is required for mRNA cap methylation by the enzyme.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents RNA-directed RNA polymerase (also known as the large or L protein) from various Hantaviruses. The L protein of hantaviruses is an RNA transcriptase and replicase that transcribes mRNAs and replicates the genomic RNA using antigenomic RNA as an intermediate []. It also appears to have endonuclease activity.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents RNA-directed RNA polymerase (also known as protein P2) from various Cystoviruses, such as Bacteriophage phi-6 and Bacteriophage phi-13 []. The RdRp protein of Cystoviruses is capable of primer-independent initiation, as are many RNA polymerases. The structure of this polymerase revealed an initiation platform, composed of a loop in the C-terminal domain that was essential for de novo initiation, a similar element having been identified in Hepatitis C virus RNA-dependent RNA polymerase [].
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.Flaviviruses produce a polyprotein from the ssRNA genome. The polyprotein is cleaved to a number of products one of which is NS5. Recombinant dengue type 1 virus NS5 protein expressed in Escherichia coli exhibits RNA-dependent RNA polymerase activity. This RNA-directed RNA polymerase possesses a number of short regions and motifs homologous to other RNA-directed RNA polymerases []. NS5 binds to a the stem loop A (SLA) at the 5' extremity of Flavivirus genome and regulates translation of the viral genome [, ].
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry corresponds to a relatively conserved segment of 147 - 180 aa of RdRp or its catalytic subunit. The proteins in this family are: RNA polymerase PB1 subunits of Orthomyxoviruses and RNA polymerases (L proteins) of Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents RNA-directed RNA polymerase (also known as the large structural protein) from various Filoviruses []. The large structural protein (or L protein) carries three enzymatic activities: RNA-directed RNA polymerase (), mRNA (guanine-N(7)-)-methyltransferase (), and mRNA guanylyltransferase (). The viral mRNA guanylyl transferase displays a different biochemical reaction than the cellular enzyme. The template is composed of the viral RNA tightly encapsidated by the nucleoprotein (N). The protein can function either as transcriptase or as replicase. The transcriptase synthesises subsequently subgenomic RNAs, assuring their capping and polyadenylation by a stuttering mechanism. The replicase mode is dependent on intracellular N protein concentration. In this mode, the polymerase replicates the whole viral genome without recognizing the transcriptional signals.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This entry represents RNA-directed RNA polymerase (also known as the large structural protein) from various Rhabdoviruses, such as Vesicular stomatitis Indiana virus []. The large structural protein (or L protein) carries four enzymatic activities: RNA-directed RNA polymerase (), mRNA (guanine-N(7)-)-methyltransferase (), mRNA guanylyltransferase (), and poly(A) synthetase. The viral mRNA guanylyl transferase displays a different biochemical reaction than the cellular enzyme. The template is composed of the viral RNA tightly encapsidated by the nucleoprotein (N). The protein can function either as transcriptase or as replicase. The transcriptase synthesises subsequently five subgenomic RNAs, assuring their capping and polyadenylation by a stuttering mechanism. The replicase mode is dependent on intracellular N protein concentration. In this mode, the polymerase replicates the whole viral genome without recognizing the transcriptional signals.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.This superfamily represents the N-terminal region of RNA-directed RNA polymerase (also known as protein P2) from various Cystoviruses, such as Bacteriophage phi-6 and Bacteriophage phi-13 []. The RdRp protein of Cystoviruses is capable of primer-independent initiation, as are many RNA polymerases.
This entry contains coronavirus (CoV) cysteine endopeptidases that belong to MEROPS peptidase family C16 (subfamilies C16A and C16B, clan CA). These peptidases are involved in viral polyprotein processing, releasing NSP1, NSP2 and NSP3 proteins []and they also function as deubiquitinating and deISG15ylating (interferon-induced gene 15) enzymes, disrupting host viral immune response to facilitate viral proliferation and replication. Therefore, this is an important target to develop antiviral treatments [].All coronaviruses encode between one and two accessory cysteine proteinases that recognise and process one or three sites in the amino-terminal half of the replicase polyprotein during assembly of the viral replication complex. MHV, HCoV and TGEV encode two accessory proteinases, called coronavirus papain-like proteinase 1 and 2 (PL1-PRO and PL2-PRO) []. IBV and SARS encodes only one called PL-PRO (PL2-PRO, conserved in all CoVs) [, , ]. The structures of both PL-PROs are similar and they also have restricted specificities. The PL1-PRO of TGEV cleaves the polyprotein between Nsp2-Nsp3 recognising the Lys-Met-Gly-Gly motif, and recognises Leu-Arg-Gly-Gly in ubiquitin (ub) which shows that it is able to accommodate residues as different as Lys and Leu. In contrast, PL-PRO from SARS-CoV recognises Leu-Xaa-Gly-Gly (Xaa could be any amino acid) and cleaves peptide bonds between Nsp1-Nsp2, Nsp2-Nsp3 and between Nsp3-Nsp4 [, , ]. In Ub and ISG15 proteins, it recognises Leu-Arg-Gly-Gly motifs. SARS-CoV and SARS-CoV-2 are closely related but exhibit different host substrate preferences: SARS-CoV-2 PL-PRO preferentially cleaves the ubiquitin-like ISG15, whereas SARS-CoV PL-PRO predominantly targets ubiquitin chains [, ].The peptidase family C16 domain is about 260 amino acids in length and the solved structures determined that it consists of thumb, palm, and fingers subdomains. The thumb is comprised of six α-helices and a small β-hairpin; the fingers subdomain is made of six β-strands and two α-helices and includes a zinc binding site, in which the zinc ion is coordinated by four cysteine residues. Zinc binding is essential for structural integrity and protease activity, with a conformation that varies most between different PL-PRO structures. The palm subdomain is comprised of six β-strands and includes the catalytic residues Cys-His-Asp, located at the interface between the thumb and palm subdomains [].
A small region that overlaps with a nuclear localization signal and binds to the RNA primer contains three aspartates that are essential for catalysis. Sequence and secondary structure comparisons of regions surrounding these aspartates with sequences of other polymerases revealed a significant homology to the palm structure of DNA polymerase beta, terminal deoxynucleotidyltransferase and DNA polymerase IV of Saccharomyces cerevisiae, all members of the family X of polymerases. This homology extends as far as cca: tRNA nucleotidyltransferase and streptomycin adenylyltransferase, an antibiotic resistance factor [, ].Proteins containing this domain include kanamycin nucleotidyltransferase (KNTase) which is a plasmid-coded enzyme responsible for some types of bacterial resistance to aminoglycosides. KNTase inactivates antibiotics by catalysing the addition of a nucleotidyl group onto the drug. In experiments, Mn2+ strongly stimulated this reaction due to a 50-fold lower Ki for 8-azido-ATP in the presence of Mn2+. Mutations of the highly conservedAsp residues 113, 115, and 167, critical for metal binding in the catalytic domain of bovine poly(A) polymerase, led to a strongreduction of cross-linking efficiency, and Mn2+ no longer stimulated the reaction. Mutations in the region of the "helical turn motif"(a domain binding the triphosphate moiety of the nucleotide) and in the suspected nucleotide-binding helix of bovine poly(A) polymeraseimpaired ATP binding and catalysis. The results indicate that ATP is bound in part by the helical turn motif and in part by a region thatmay be a structural analogue of the fingers domain found in many polymerases.
This entry contains the RNA-dependent RNA polymerase (RdRp) of human coronavirus HKU1, murine hepatitis virus, and similar proteins from betacoronaviruses in the embecovirus subgenera (A lineage).Coronaviruses (CoVs) utilize a multi-subunit replication/transcription machinery. A set of non-structural proteins (NSPs) generated as cleavage products of the ORF1a and ORF1ab viral polyproteins assemble to facilitate viral replication and transcription. A key component, the RNA-dependent RNA polymerase (RdRp, also known as NSP12), catalyses the synthesis of viral RNA and thus plays a central role in the replication and transcription cycle of CoV, possibly interacting with its co-factors, NSP7 and NSP8. RdRp is therefore considered a primary target for nucleotide analog antiviral inhibitors such as remdesivir. NSP12 contains a RdRp domain as well as a large N-terminal extension that adopts a nidovirus RdRp-associated nucleotidyltransferase (NiRAN) architecture. The RdRp domain displays a right hand with three functional subdomains, called fingers, palm, and thumb. All RpRps contain conserved polymerase motifs (A-G), located in the palm (A-E motifs) and finger (F-G) subdomains. All these motifs have been implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides [].
This entry contains the RNA-dependent RNA polymerase (RdRp) of bat coronavirus HKU9 and similar proteins from betacoronaviruses in the nobecovirus subgenera (D lineage).Coronaviruses (CoVs) utilize a multi-subunit replication/transcription machinery. A set of non-structural proteins (NSPs) generated as cleavage products of the ORF1a and ORF1ab viral polyproteins assemble to facilitate viral replication and transcription. A key component, the RNA-dependent RNA polymerase (RdRp, also known as NSP12), catalyses the synthesis of viral RNA and thus plays a central role in the replication and transcription cycle of CoV, possibly interacting with its co-factors, NSP7 and NSP8. RdRp is therefore considered a primary target for nucleotide analog antiviral inhibitors such as remdesivir. NSP12 contains a RdRp domain as well as a large N-terminal extension that adopts a nidovirus RdRp-associated nucleotidyltransferase (NiRAN) architecture. The RdRp domain displays a right hand with three functional subdomains, called fingers, palm, and thumb. All RpRps contain conserved polymerase motifs (A-G), located in the palm (A-E motifs) and finger (F-G) subdomains. All these motifs have been implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides [].
This entry contains the RNA-dependent RNA polymerase (RdRp) of Middle East respiratory syndrome (MERS)-related CoV, bat-CoV HKU5, and similar proteins from betacoronaviruses in the merbecovirus subgenera (C lineage).Coronaviruses (CoVs) utilize a multi-subunit replication/transcription machinery. A set of non-structural proteins (NSPs) generated as cleavage products of the ORF1a and ORF1ab viral polyproteins assemble to facilitate viral replication and transcription. A key component, the RNA-dependent RNA polymerase (RdRp, also known as NSP12), catalyses the synthesis of viral RNA and thus plays a central role in the replication and transcription cycle of CoV, possibly interacting with its co-factors, NSP7 and NSP8. RdRp is therefore considered a primary target for nucleotide analog antiviral inhibitors such as remdesivir. NSP12 contains a RdRp domain as well as a large N-terminal extension that adopts a nidovirus RdRp-associated nucleotidyltransferase (NiRAN) architecture. The RdRp domain displays a right hand with three functional subdomains, called fingers, palm, and thumb. All RpRps contain conserved polymerase motifs (A-G), located in the palm (A-E motifs) and finger (F-G) subdomains. All these motifs have been implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides [].
This entry contains the RNA-dependent RNA polymerase (RdRp) of Severe acute respiratory syndrome coronavirus (SARS-CoV), SARS-CoV-2 (also known as 2019 novel CoV (2019-nCoV) or COVID-19 virus), and similar proteins from betacoronaviruses in the sarbecovirus subgenera (B lineage).Coronaviruses (CoVs) utilize a multi-subunit replication/transcription machinery. A set of non-structural proteins (NSPs) generated as cleavage products of the ORF1a and ORF1ab viral polyproteins assemble to facilitate viral replication and transcription. A key component, the RNA-dependent RNA polymerase (RdRp, also known as NSP12), catalyses the synthesis of viral RNA and thus plays a central role in the replication and transcription cycle of CoV, possibly interacting with its co-factors, NSP7 and NSP8. RdRp is therefore considered a primary target for nucleotide analog antiviral inhibitors such as remdesivir. NSP12 contains a RdRp domain as well as a large N-terminal extension that adopts a nidovirus RdRp-associated nucleotidyltransferase (NiRAN) architecture. The RdRp domain displays a right hand with three functional subdomains, called fingers, palm, and thumb. All RpRps contain conserved polymerase motifs (A-G), located in the palm (A-E motifs) and finger (F-G) subdomains. All these motifs have been implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides [].
This entry contains the RNA-dependent RNA polymerase (RdRp) of deltacoronaviruses.Coronaviruses (CoVs) utilize a multi-subunit replication/transcription machinery. A set of non-structural proteins (NSPs) generated as cleavage products of the ORF1a and ORF1ab viral polyproteins assemble to facilitate viral replication and transcription. A key component, the RNA-dependent RNA polymerase (RdRp, also known as NSP12), catalyses the synthesis of viral RNA and thus plays a central role in the replication and transcription cycle of CoV, possibly interacting with its co-factors, NSP7 and NSP8. RdRp is therefore considered a primary target for nucleotide analog antiviral inhibitors such as remdesivir. NSP12 contains a RdRp domain as well as a large N-terminal extension that adopts a nidovirus RdRp-associated nucleotidyltransferase (NiRAN) architecture. The RdRp domain displays a right hand with three functional subdomains, called fingers, palm, and thumb. All RpRps contain conserved polymerase motifs (A-G), located in the palm (A-E motifs) and finger (F-G) subdomains. All these motifs have been implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides [].
This entry contains the RNA-dependent RNA polymerase (RdRp) of alphacoronaviruses, including human coronaviruses (HCoVs), HCoV-NL63, and HCoV-229E.CoVs utilize a multi-subunit replication/transcription machinery. A set of non-structural proteins (Nsps) generated as cleavage products of the ORF1a and ORF1ab viral polyproteins assemble to facilitate viral replication and transcription. A key component, the RNA-dependent RNA polymerase (RdRp, also known as NSP12), catalyses the synthesis of viral RNA and thus plays a central role in the replication and transcription cycle of CoV, possibly interacting with its co-factors, NSP7 and NSP8. RdRp is therefore considered a primary target for nucleotide analog antiviral inhibitors such as remdesivir [].NSP12 containsa RdRp domain as well as a large N-terminal extension that adopts a nidovirus RdRp-associated nucleotidyltransferase (NiRAN) architecture. The RdRp domain displays a right hand with three functional subdomains, called fingers, palm, and thumb. All RpRps contain conserved polymerase motifs (A-G), located in the palm (A-E motifs) and finger (F-G) subdomains. All these motifs have been implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides [].
This entry contains the RNA-dependent RNA polymerase (RdRp) of gammacoronaviruses, including the RdRp of avian infectious bronchitis virus (IBV) and similar proteins.CoVs utilize a multi-subunit replication/transcription machinery. A set of non-structural proteins (Nsps) generated as cleavage products of the ORF1a and ORF1ab viral polyproteins assemble to facilitate viral replication and transcription. A key component, the RNA-dependent RNA polymerase (RdRp, also known as NSP12), catalyses the synthesis of viral RNA and thus plays a central role in the replication and transcription cycle of CoV, possibly interacting with its co-factors, NSP7 and NSP8. RdRp is therefore considered a primary target for nucleotide analog antiviral inhibitors such as remdesivir [].NSP12 contains a RdRp domain as well as a large N-terminal extension that adopts a nidovirus RdRp-associated nucleotidyltransferase (NiRAN) architecture. The RdRp domain displays a right hand with three functional subdomains, called fingers, palm, and thumb. All RpRps contain conserved polymerase motifs (A-G), located in the palm (A-E motifs) and finger (F-G) subdomains. All these motifs have been implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides [].
Protein ubiquitination is a reversible posttranslational modification, whichaffects a large number of cellular processes including protein degradation,trafficking, cell signaling and the DNA damage response. Ubiquitination isreversible, and dedicated deubiquitinases exist which hydrolyze isopeptidebonds. Ubiquitin specific proteases (USPs) () are the largest family of deubiquitinating enzymes. USP domains consist of a common conserved catalytic core which is interspersed at five points with insertions, some of which as large as the catalytic domain itself. The insertions can fold into independent domains that can be involved in the regulation of deubiquitinase activity. As commonly found in signaling proteins, many USP deubiquitinases have a modular architecture, and not only contain a catalytic domain but also additional protein-protein interaction and localisation domains. Most USP domains cleave the isopeptide linkage between two ubiquitin molecules, and hence contain (at least) two ubiquitin-binding sites, one for the distal ubiquitin, the C terminus of which is linked to the Lys residue on the proximal ubiquitin in a second, proximal binding site []. The USP domain forms the peptidase family C19 [].The USP catalytic core can be divided into six conserved boxes that arepresent in all USP domains. Box 1 contains the catalytic Cys residue, box 5contains the catalytic His, and box 6 contains the catalytic Asp/Asn residue.All boxes show several additional conserved features and residues. Boxes 3 and4 contain a Cys-X-X-Cys motif each, which have been shown to constitute afunctional zinc-binding motif. Potentially, zinc-binding facilitates foldingof the USP core, helping the interaction of sequence motifs some few hundredresidues apart. USP domains share a common conserved fold.The USP domain resembles an open hand containing Thumb, Palm and Fingerssubdomains. The catalytic triad resides between the Thumb (Cys) and Palmsubdomains (His/Asp) [].This entry represents the entire USP domain.
DNA is the biological information that instructs cells how to exist in an ordered fashion: accurate replication is thus one of the most important events in the life cycle of a cell. This function is performed by DNA- directed DNA-polymerases ) by adding nucleotide triphosphate (dNTP) residues to the 5'-end of the growing chain of DNA, using a complementary DNA chain as a template. Small RNA molecules are generally used as primers for chain elongation, although terminal proteins may also be used for the de novo synthesis of a DNA chain. Even though there are 2 different methods of priming, these are mediated by 2 very similar polymerases classes, A and B, with similar methods of chain elongation. A number of DNA polymerases have been grouped under the designation of DNA polymerase family B. Six regions of similarity (numbered from I to VI) are found in all or a subset of the B family polymerases. The most conserved region (I) includes a conserved tetrapeptide with two aspartate residues. Its function is not yet known, however, it has been suggested that it may be involved in binding a magnesium ion. All sequences in the B family contain a characteristic DTDS motif, and possess many functional domains, including a 5'-3' elongation domain, a 3'-5' exonuclease domain [], a DNA binding domain, and binding domains for both dNTP's and pyrophosphate []. The DNA polymerase structure resembles a right hand with fingers, palm, and thumb, with an active site formed by a palm holding the catalytic residues, a thumb that binds the primer:template DNA and fingers interacting with incoming nucleotide, and the N and Exo domains extend from the finger toward the thumb [, , ].This superfamily represents the thumb domain found at the C-terminal of the DNA polymerase family B proteins.
Positive-stranded RNA (+RNA) viruses that belong to the order Nidovirales infect a wide range of vertebrates (families Arteriviridae and Coronaviridae) or invertebrates (Mesoniviridae and Roniviridae). Examples of nidoviruses with high economic and societal impact are the arterivirus porcine reproductive and respiratory syndrome virus (PRRSV) and the zoonotic coronaviruses (CoVs) causing severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS) and Covid-19 (SARS-CoV-2) in humans. In all nidoviruses, at least two-thirds of the capacity of the polycistronic genome is occupied by the two large open reading frames (ORFs; 1a and 1b) that together constitute the replicase gene. The two polyproteins produced, pp1a (ORF1a-encoded) and pp1ab (ORF1a/ORF1b-encoded), are processed to a dozen or more proteins by the virus main protease (3CLpro, encoded in ORF1a) with possible involvement of other protease(s). These and other proteins form a membrane-bound replication-transcription complex (RTC) that invariably includes two key ORF1b-encoded subunits: the RNA-dependent RNA polymerase (RdRp) and a superfamily 1 helicase domain (HEL1), which is fused with a multinuclear Zn-binding domain (ZBD). The RNA-dependent RNA polymerase (RdRp) domain of nidoviruses resides in a cleavage product of the replicase polyprotein named non- structural protein (nsp) 12 in coronaviruses and nsp9 in arteriviruses. In all nidoviruses, the C-terminal RdRp domain is linked to a conserved N-terminal domain, which has been coined NiRAN (nidovirus RdRp-associated nucleotidyl transferase). The NiRAN domain has an essential nucleotidylation activity and its potential functions in nidovirus replication may include RNA ligation, protein-primed RNA synthesis, and the guanylyl-transferase function that is necessary for mRNA capping [, , , , ].The NiRAN domain is characterised by an α+β fold composed of eight α-helices and a five stranded β-sheet. In addition, an N-terminal β-hairpin interacts with the palm subdomain of the RdRp domain [, ].
DNA is the biological information that instructs cells how to exist in an ordered fashion: accurate replication is thus one of the most important events in the life cycle of a cell. This function is performed by DNA- directed DNA-polymerases ) by adding nucleotide triphosphate (dNTP) residues to the 5'-end of the growing chain of DNA, using a complementary DNA chain as a template. Small RNA molecules are generally used as primers for chain elongation, although terminal proteins may also be used for the de novo synthesis of a DNA chain. Even though there are 2 different methods of priming, these are mediated by 2 very similar polymerases classes, A and B, with similar methods of chain elongation. A number of DNA polymerases have been grouped under the designation of DNA polymerase family B. Six regions of similarity (numbered from I to VI) are found in all or a subset of the B family polymerases. The most conserved region (I) includes a conserved tetrapeptide with two aspartate residues. Its function is not yet known, however, it has been suggested that it may be involved in binding a magnesium ion. All sequences in the B family contain a characteristic DTDS motif, and possess many functional domains, including a 5'-3' elongation domain, a 3'-5' exonuclease domain [], a DNA binding domain, and binding domains for both dNTP's and pyrophosphate []. The DNA polymerase structure resembles a right hand with fingers, palm, and thumb, with an active site formed by a palm holding the catalytic residues, a thumb that binds the primer:template DNA and fingers interacting with incoming nucleotide, and the N and Exo domains extend from the finger toward the thumb [, , ].This domain of DNA polymerase B appears to consist of more than one activities, possibly including elongation, DNA-binding and dNTP binding [].
Protein ubiquitination is a reversible posttranslational modification, whichaffects a large number of cellular processes including protein degradation,trafficking, cell signaling and the DNA damage response. Ubiquitination isreversible, and dedicated deubiquitinases exist which hydrolyze isopeptidebonds. Ubiquitin specific proteases (USPs) ) are the largest family of deubiquitinating enzymes. USP domains consist of a common conserved catalytic core which is interspersed at five points with insertions, some of which as large as the catalytic domain itself. The insertions can fold into independent domains that can be involved in the regulation of deubiquitinase activity. As commonly found in signaling proteins, many USP deubiquitinases have a modular architecture, and not only contain a catalytic domain but also additional protein-protein interaction and localization domains. Most USP domains cleave the isopeptide linkage between two ubiquitin molecules, and hence contain (at least) two ubiquitin-binding sites, one for the distal ubiquitin, the C terminus of which is linked to the Lys residue on the proximal ubiquitin in a second, proximal binding site []. The USP domain forms the peptidase family C19 [].The USP catalytic core can be divided into six conserved boxes that arepresent in all USP domains. Box 1 contains the catalytic Cys residue, box 5contains the catalytic His, and box 6 contains the catalytic Asp/Asn residue.All boxes show several additional conserved features and residues. Boxes 3 and4 contain a Cys-X-X-Cys motif each, which have been shown to constitute afunctional zinc-binding motif. Potentially, zinc-binding facilitates foldingof the USP core, helping the interaction of sequence motifs some few hundredresidues apart. USP domains share a common conserved fold.The USP domain resembles an open hand containing Thumb, Palm and Fingerssubdomains. The catalytic triad resides between the Thumb (Cys) and Palmsubdomains (His/Asp) [].This entry represents two conserved sites for the USP domain. The first oneis around the catalytic cysteine in box 1, and the second around the catalytichistidine in box 5.
RNA-directed RNA polymerase (RdRp) () is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage [, ]. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear.The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product []. All the RNA-directed RNA polymerases, and many DNA-directed polymerases, employ a fold whose organisation has been likened to the shape of a right hand with three subdomains termed fingers, palm and thumb []. Only the catalytic palm subdomain, composed of a four-stranded antiparallel β-sheet with two α-helices, is well conserved among all of these enzymes. In RdRp, the palm subdomain comprises three well conserved motifs (A, B and C). Motif A (D-x(4,5)-D) and motif C (GDD) are spatially juxtaposed; the Asp residues of these motifs are implied in the binding of Mg2+ and/or Mn2+. The Asn residue of motif B is involved in selection of ribonucleoside triphosphates over dNTPs and thus determines whether RNA is synthesised rather than DNA [].The domain organisation []and the 3D structure of the catalytic centre of a wide range of RdPp's, even those with a low overall sequence homology, are conserved. The catalytic centre is formed by several motifs containing a number of conserved amino acid residues.There are 4 superfamilies of viruses that cover all RNA containing viruses with no DNA stage:Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae: viral RNA-directed RNA polymerases including all positive-strand RNA viruses with no DNA stage, double-strand RNA viruses, and the Cystoviridae, Reoviridae, Hypoviridae, Partitiviridae, Totiviridae families.Mononegavirales (negative-strand RNA viruses with non-segmented genomes).Negative-strand RNA viruses with segmented genomes, i.e. Orthomyxoviruses (including influenza A, B, and C viruses, Thogotoviruses, and the infectious salmon anemia virus), Arenaviruses, Bunyaviruses, Hantaviruses, Nairoviruses, Phleboviruses, Tenuiviruses and Tospoviruses.Birnaviridae family of dsRNA viruses.The RNA-directed RNA polymerases in the first of the above superfamilies can be divided into the following three subgroups:All positive-strand RNA eukaryotic viruses with no DNA stage.All RNA-containing bacteriophages -there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages).Reoviridae family of dsRNA viruses.The nucleotide sequence for the RNA of Potato leafroll virus (PLrV) has been determined [, ]. The sequence contains six large open reading frames (ORFs). The 5' coding region encodes two polypeptides of 28K and 70K, which overlap in different reading frames; it is suggested that the third ORF in the 5' block is translated by frameshift read through near the end of the 70K protein, yielding a 118K polypeptide []. The C-terminal part of the 118K protein contains a consensus sequence for RNA-dependent RNA-polymerases [].The genomic RNA sequence of Southern bean mosaic virus (SBMV) has been determined []. The genome contains four ORFs. The largest ORF encodes the two largest proteins translated in cell-free extracts from full-length virion RNA []. Segments of the predicted amino acid sequence of this ORF resemble those of known viral RNA-polymerases, ATP-binding proteins and viral genome-linked proteins [].The genome sequence of Pea enation mosaic virus (PEMV) RNA 1 shows strong organisational relationships and sequence similarities to the Beet western yellows virus (BWYV) and PLrV []. Sequence analysis reveals five predominant ORFs. The third ORF is characterised by a number of RNA-polymerase motifs and a helicase-like motif typical of RNA-dependent RNA-polymerases []. It overlaps (out of frame) the ORF 2 product and is proposed to be expressed by a frameshift fusion of ORF 2 and ORF 3 [].The PLrV sequence shows some similarities to the putative polymerase of SBMV [], and more extensive similarities to the corresponding BWYV polypeptide [].
The insulin-like growth factors (IGF-I and IGF-II) bind to specific binding proteins in extracellular fluids with high affinity [, ]. These IGF-binding proteins (IGFBP) prolong the half-life of the IGFs and have been shown to either inhibit or stimulate the growth promoting effects of the IGFs on cells culture. They seem to alter the interaction of IGFs with their cell surface receptors. The IGFBP family comprises six proteins (IGFBP-1 to -6) that bind to IGFs with high affinity. The precursor forms of all six IGFBPs have secretory signal peptides. All IGFBPs share a common domain organisation and also a high degree of similarity in their primary protein structure. The highest conservation is found in the N- and C-terminal cysteine-rich regions. Twelve conserved cysteines (ten in IGFBP-6) are found in the N-terminal domain, and six are found in the C-terminal domain. Both the N- and C-terminal domains participate in binding to IGFs, although the specific roles each of these domains in IGF binding have not been decisively established. In general, the strongest binding to IGFs is shown by amino-terminal fragments, which, however bind to IGF with 10- to 1000-fold lower affinity than full length IGFBPs. The central weakly conserved part (L domain) contains most of the cleavage sites for specific proteases [, ].The N-terminal domain is about 80 residues in length and has an L-like structure. It can be divided into two subdomains that are connected by a short stretch of amino acids. The two subdomains are perpendicular to each other, creating the "L"shape for the whole N-terminal domain. The core of the first subdomain presents a novel fold stabilised by a short two-stranded beta sheet and four disulphide bridges forming a disulphide bond ladder-like structure. The beta sheet and disulphide bridges are all in one plane, making the structure appear flat from one side like the "palm"of a hand. The palm is extended with a "thumb"segment in various IGFBPs. The thumb segment consists of the very N-terminal residues and contains a consensus XhhyC motif, where h is a hydrophobic amino acid and y is positively charged. The second subdomain adopts a globular fold whose scaffold is secured by an inside packing of two cysteines bridges stabilised by a three-stranded beta sheet [, ].The following growth-factor inducible proteins are structurally related to IGFBPs and could function as growth-factor binding proteins [, ]:Mouse protein cyr61 and its probable chicken homologue, protein CEF-10.Human connective tissue growth factor (CTGF) and its mouse homologue, protein FISP-12.Vertebrate protein NOV.This entry represents a conserved cysteine-rich region located in the N-terminal IGFBP domain.
