| Primary Identifier | IPR014016 | Type | Domain |
| Short Name | UvrD-like_ATP-bd |
| description | Helicases have been classified in 5 superfamilies (SF1-SF5). All of theproteins bind ATP and, consequently, all of them carry the classical Walker A(phosphate-binding loop or P-loop) and Walker B(Mg2+-binding aspartic acid) motifs. For the two largest groups, commonlyreferred to as SF1 and SF2, a total of seven characteristic motifs have beenidentified []which are distributed over two structural domains, anN-terminal ATP-binding domain and a C-terminal domain. UvrD-like DNA helicasesbelong toSF1, but they differ from classical SF1/SF2 by alarge insertion in each domain. UvrD-like DNA helicases unwind DNA with a3'-5' polarity [].Crystal structures of several uvrD-like DNA helicases have been solved [, , ]. They are monomeric enzymes consisting of twodomains with a common α-β RecA-like core. The ATP-binding site issituated in a cleft between the N terminus of the ATP-binding domain and thebeginning of the C-terminal domain. The enzyme crystallizes in two differentconformations (open and closed). The conformational difference between the twoforms comprises a large rotation of the end of the C-terminal domain byapproximately 130 degrees. This "domain swiveling"was proposed to be an importantaspect of the mechanism of the enzyme [].Some proteins that belong to the UvrD-like DNA helicase family are listedbelow:Bacterial UvrD helicase. It is involved in the post-incision events ofnucleotide excision repair and methyl-directed mismatch repair. It unwindsDNA duplexes with 3'-5' polarity with respect to the bound strand andinitiates unwinding most effectively when a single-stranded region ispresent.Gram-positive bacterial pcrA helicase, an essential enzyme involved in DNArepair and rolling circle replication. The Staphylococcus aureus pcrAhelicase has both 5'-3' and 3'-5' helicase activities.Bacterial rep proteins, a single-stranded DNA-dependent ATPase involved inDNA replication which can initiate unwinding at a nick in the DNA. It bindsto the single-stranded DNA and acts in a progressive fashion along the DNAin the 3' to 5' direction.Bacterial helicase IV (helD gene product). It catalyzes the unwinding ofduplex DNA in the 3'-5' direction.Bacterial recB protein. RecBCD is a multi-functional enzyme complex thatprocesses DNA ends resulting from a double-strand break. RecB is a helicasewith a 3'-5' directionality.Fungal srs2 proteins, an ATP-dependent DNA helicase involved in DNA repair. The polarity of the helicase activity was determined to be 3'-5'.This domain is also found bacterial helicase-nuclease complex AddAB, both in subunit AddA and AddB. The AddA subunit is responsable for the helicase activity. AddB also harbors a putative ATP-binding domain which does not play a role as a secondary DNA motor, but that it may instead facilitate the recognition of the recombination hotspot sequences [].This entry represents the ATP-binding domain found in AddA, AddB and UvrD-like helicases. |
