This entry includes protein cordon-bleu (COBL) and COBLL1. Single WH2 domains can sequester G-actin. COBL contains three G-actin-binding WH2 domains and act as a dynamizer of actin assembly. COBL has profilin-like filament nucleating and severing activities []. It is a CaM-controlled component important for early neuronal morphogenesis []. Cordon-Bleu-like (COBLL), an evolutionary ancestor of the actin nucleator Cobl, contains only one WH2 domain. It functions with the F-actin-binding protein Abp1 in Ca2+/CaM regulated dendritic branching [].
Members of this family are involved in cobalamin synthesis. The gene encoded by has been designated cbiH but in fact represents a fusion between cbiH and cbiG. As other multi-functional proteins involved in cobalamin biosynthesis catalyse adjacent steps in the pathway, including CysG, CobL (CbiET), CobIJ and CobA-HemD, it is therefore possible that CbiG catalyses a reaction step adjacent to CbiH. In the anaerobic pathway such a step could be the formation of a gamma lactone, which is thought to help to mediate the anaerobic ring contraction process [].
Members of this family are involved in cobalamin synthesis. The gene encoded by has been designated cbiH but in fact represents a fusion between cbiH and cbiG. As other multi-functional proteins involved in cobalamin biosynthesis catalyse adjacent steps in the pathway, including CysG, CobL (CbiET), CobIJ and CobA-HemD, it is therefore possible that CbiG catalyses a reaction step adjacent to CbiH. In the anaerobic pathway such a step could be the formation of a gamma lactone, which is thought to help to mediate the anaerobic ring contraction process []. Within the cobalamin synthesis pathway CbiG catalyses the both the opening of the lactone ring and the extrusion of the two-carbon fragment of cobalt-precorrin-5A from C-20 and its associated methyl group (deacylation) to give cobalt-precorrin-5B. The N-terminal of the enzyme is conserved in this family, and the C-terminal and the mid-sections are conserved independently in other families, CbiG_C and CbiG_mid, although the distinct function of each region is unclear.
Cobalamin (vitamin B12) is a structurally complex cofactor, consisting of a modified tetrapyrrole with a centrally chelated cobalt. Cobalamin is usually found in one of two biologically active forms: methylcobalamin and adocobalamin. Most prokaryotes, as well as animals, have cobalamin-dependent enzymes, whereas plants and fungi do not appear to use it. In bacteria and archaea, these include methionine synthase, ribonucleotide reductase, glutamate and methylmalonyl-CoA mutases, ethanolamine ammonia lyase, and diol dehydratase []. In mammals, cobalamin is obtained through the diet, and is required for methionine synthase and methylmalonyl-CoA mutase []. There are at least two distinct cobalamin biosynthetic pathways in bacteria []:Aerobic pathway that requires oxygen and in which cobalt is inserted late in the pathway []; found in Pseudomonas denitrificans and Rhodobacter capsulatus.Anaerobic pathway in which cobalt insertion is the first committed step towards cobalamin synthesis [, ]; found in Salmonella typhimurium, Bacillus megaterium, and Propionibacterium freudenreichii subsp. shermanii. Either pathway can be divided into two parts: (1) corrin ring synthesis (differs in aerobic and anaerobic pathways) and (2) adenosylation of corrin ring, attachment of aminopropanol arm, and assembly of the nucleotide loop (common to both pathways) []. There are about 30 enzymes involved in either pathway, where those involved in the aerobic pathway are prefixed Cob and those of the anaerobic pathway Cbi. Several of these enzymes are pathway-specific: CbiD, CbiG, and CbiK are specific to the anaerobic route of S. typhimurium, whereas CobE, CobF, CobG, CobN, CobS, CobT, and CobW are unique to the aerobic pathway of P. denitrificans.This entry represents CobL precorrin-6Y C5,15-methyltransferase () from the aerobic pathway. CobL is a bifunctional enzyme that catalyses two methylations (at C-5 and C-15) in precorrin-6Y, as well as the decarboxylation of the acetate side chain located in ring C, in order to generate precorrin-8X. []. In the anaerobic pathway, two enzymes are required to produce precorrin-8X: CbiE and CbiT, which can be fused as CbiET (sometimes also called CobL) [].
Cobalamin (vitamin B12) is a structurally complex cofactor, consisting of a modified tetrapyrrole with a centrally chelated cobalt. Cobalamin is usually found in one of two biologically active forms: methylcobalamin and adocobalamin. Most prokaryotes, as well as animals, have cobalamin-dependent enzymes, whereas plants and fungi do not appear to use it. In bacteria and archaea, these include methionine synthase, ribonucleotide reductase, glutamate and methylmalonyl-CoA mutases, ethanolamine ammonia lyase, and diol dehydratase []. In mammals, cobalamin is obtained through the diet, and is required for methionine synthase and methylmalonyl-CoA mutase []. There are at least two distinct cobalamin biosynthetic pathways in bacteria []:Aerobic pathway that requires oxygen and in which cobalt is inserted late in the pathway []; found in Pseudomonas denitrificans and Rhodobacter capsulatus.Anaerobic pathway in which cobalt insertion is the first committed step towards cobalamin synthesis [, ]; found in Salmonella typhimurium, Bacillus megaterium, and Propionibacterium freudenreichii subsp. shermanii. Either pathway can be divided into two parts: (1) corrin ring synthesis (differs in aerobic and anaerobic pathways) and (2) adenosylation of corrin ring, attachment of aminopropanol arm, and assembly of the nucleotide loop (common to both pathways) []. There are about 30 enzymes involved in either pathway, where those involved in the aerobic pathway are prefixed Cob and those of the anaerobic pathway Cbi. Several of these enzymes are pathway-specific: CbiD, CbiG, and CbiK are specific to the anaerobic route of S. typhimurium, whereas CobE, CobF, CobG, CobN, CobS, CobT, and CobW are unique to the aerobic pathway of P. denitrificans.The CbiT subunit of precorrin-6Y C5,15-methyltransferase () is a bifunctional enzyme that catalyses two methylations (at C-5 and C-15) in precorrin-6Y, as well as the decarboxylation of the acetate side chain located in ring C, in order to generate precorrin-8X. In the anaerobic pathway, two enzymes are required to produce precorrin-8X: CbiE and CbiT, which can be fused as CbiET (sometimes called CobL) []. In the aerobic pathway, the enzyme is a fusion of CbiE and CbiT which is refered to as CobL []. CbiT is thought to catalyse one of the methylation reactions, though this has not been completely proven [].This entry represents the CbiT subunit of the aerobic and anaerobic enzymes. In the anaerobic proteins it comproses the entire length of the protein, while in the aerobic enzymes it is fused with CbiE to form the bifunctional CobL protein.
Cobalamin (vitamin B12) is a structurally complex cofactor, consisting of a modified tetrapyrrole with a centrally chelated cobalt. Cobalamin is usually found in one of two biologically active forms: methylcobalamin and adocobalamin. Most prokaryotes, as well as animals, have cobalamin-dependent enzymes, whereas plants and fungi do not appear to use it. In bacteria and archaea, these include methionine synthase, ribonucleotide reductase, glutamate and methylmalonyl-CoA mutases, ethanolamine ammonia lyase, and diol dehydratase []. In mammals, cobalamin is obtained through the diet, and is required for methionine synthase and methylmalonyl-CoA mutase []. There are at least two distinct cobalamin biosynthetic pathways in bacteria []:Aerobic pathway that requires oxygen and in which cobalt is inserted late in the pathway []; found in Pseudomonas denitrificans and Rhodobacter capsulatus.Anaerobic pathway in which cobalt insertion is the first committed step towards cobalamin synthesis [, ]; found in Salmonella typhimurium, Bacillus megaterium, and Propionibacterium freudenreichii subsp. shermanii. Either pathway can be divided into two parts: (1) corrin ring synthesis (differs in aerobic and anaerobic pathways) and (2) adenosylation of corrin ring, attachment of aminopropanol arm, and assembly of the nucleotide loop (common to both pathways) []. There are about 30 enzymes involved in either pathway, where those involved in the aerobic pathway are prefixed Cob and those of the anaerobic pathway Cbi. Several of these enzymes are pathway-specific: CbiD, CbiG, and CbiK are specific to the anaerobic route of S. typhimurium, whereas CobE, CobF, CobG, CobN, CobS, CobT, and CobW are unique to the aerobic pathway of P. denitrificans.This entry represents CbiE subunit of precorrin-6Y C5,15-methyltransferase () from the anaerobic pathway, a bifunctional enzyme that catalyses two methylations (at C-5 and C-15) in precorrin-6Y, as well as the decarboxylation of the acetate side chain located in ring C, in order to generate precorrin-8X. In the anaerobic pathway, two enzymes are required to produce precorrin-8X: CbiE and CbiT, which can be fused as CbiET (sometimes called CobL) []. In the aerobic pathway, the bifunctional enzyme is CobL [].
CbiT is a bifunctional enzyme that catalyses two methylations (at C-5 and C-15) in precorrin-6Y, as well as the decarboxylation of the acetate side chain located in ring C, in order to generate precorrin-8X. It participates in the biosynthesis of vitamin B12 []. In the anaerobic pathway, two enzymes are required to produce precorrin-8X: CbiE and CbiT, which can be fused as CbiET (sometimes called CobL) []. In the aerobic pathway, the enzyme is a fusion of CbiE and CbiT which is refered to as CobL []. CbiT is thought to catalyse one of the methylation reactions [, ].Cobalamin (vitamin B12) is a structurally complex cofactor, consisting of a modified tetrapyrrole with a centrally chelated cobalt. Cobalamin is usually found in one of two biologically active forms: methylcobalamin and adocobalamin. Most prokaryotes, as well as animals, have cobalamin-dependent enzymes, whereas plants and fungi do not appear to use it. In bacteria and archaea, these include methionine synthase, ribonucleotide reductase, glutamate and methylmalonyl-CoA mutases, ethanolamine ammonia lyase, and diol dehydratase []. In mammals, cobalamin is obtained through the diet, and is required for methionine synthase and methylmalonyl-CoA mutase []. There are at least two distinct cobalamin biosynthetic pathways in bacteria []:Aerobic pathway that requires oxygen and in which cobalt is inserted late in the pathway []; found in Pseudomonas denitrificans and Rhodobacter capsulatus.Anaerobic pathway in which cobalt insertion is the first committed step towards cobalamin synthesis [, ]; found in Salmonella typhimurium, Bacillus megaterium, and Propionibacterium freudenreichii subsp. shermanii. Either pathway can be divided into two parts: (1) corrin ring synthesis (differs in aerobic and anaerobic pathways) and (2) adenosylation of corrin ring, attachment of aminopropanol arm, and assembly of the nucleotide loop (common to both pathways) []. There are about 30 enzymes involved in either pathway, where those involved in the aerobic pathway are prefixed Cob and those of the anaerobic pathway Cbi. Several of these enzymes are pathway-specific: CbiD, CbiG, and CbiK are specific to the anaerobic route of S. typhimurium, whereas CobE, CobF, CobG, CobN, CobS, CobT, and CobW are unique to the aerobic pathway of P. denitrificans.
