Protein Domain : IPR000605

Type:  Domain Name:  Helicase, superfamily 3, single-stranded DNA/RNA virus
Description:  Helicases have been classified in 5 superfamilies (SF1-SF5). All of the proteins 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. Superfamily 3 consists of helicasesencoded mainly by small DNA viruses and some large nucleocytoplasmic DNA viruses [, ]. Small viruses are very dependent on the host-cell machinery toreplicate. SF3 helicase in small viruses is associated with an origin-binding domain. By pairing a domain that recognises the ori with a helicase, the viruscan bypass the host-cell-based regulation pathway and initiate its own replication. The protein binds to the viral ori leading to origin unwinding.Cellular replication proteins are then recruited to the ori and the viral DNA is replicated.In SF3 helicases the Walker A and Walker B motifs are separated by spacers of rather uniform, and relatively short, length. In addition to the A and Bmotifs this family is characterised by a third motif (C) which resides between the B motif and the C terminus of the conserved region. This motif consists ofan Asn residue preceded by a run of hydrophobic residues [].Several structures of SF3 helicases have been solved []. Theyall possess the same core alpha/beta fold, consisting of a five-stranded parallel beta sheet flanked on both sides by several alpha helices. Incontrast to SF1 and SF2 helicases, which have RecA-like core folds, the strand connectivity within the alpha/beta core domain is that of AAA+ proteins [].The SF3 helicase proteins assemble into a hexameric ring.Some proteins known to contain an SF3 helicase domain are listed below: Polyomavirus large T antigen. It initiates DNA unwinding and replication via interactions with the viral origin of replication.Papillomavirus E1 protein. An ATP-dependent DNA helicase required for initiation of viral DNA replication.Parvovirus Rep/NS1 protein, which is also required for the initiation of viral replication.Poxviridae and other large DNA viruses D5 protein.Bacteriophage DNA primase/helicase protein.Bacterial prophage DNA primase/helicase protein.The entry represents the core alpha/beta fold of the SF3 helicase domain found predominantly in DNA viruses. Short Name:  Helicase_SF3_ssDNA/RNA_vir
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1 Child Features

DB identifier Type Name
IPR014759 Domain Helicase, superfamily 3, single-stranded RNA virus

0 Contains

1 Cross References

Identifier
PF00910

0 Found In

2 GO Annotations

GO Term Gene Name
GO:0003723 IPR000605
GO:0003724 IPR000605

2 Ontology Annotations

GO Term Gene Name
GO:0003723 IPR000605
GO:0003724 IPR000605

0 Parent Features

6 Proteins

DB identifier UniProt Accession Secondary Identifier Organism Name Length
Dusal.0615s00010.1.p PAC:33189858 Dunaliella salina 336  
Dusal.3121s00001.1.p PAC:33197414 Dunaliella salina 156  
Pavir.J409300.1.p PAC:37616633 Panicum virgatum 144  
Pavir.J409300.2.p PAC:37616635 Panicum virgatum 144  
Pavir.J409300.3.p PAC:37616634 Panicum virgatum 144  
Pavir.4KG258110.1.p PAC:41649575 Panicum virgatum 144  

5 Publications

First Author Title Year Journal Volume Pages PubMed ID
            15037234
            12774115
            11689653
            2156730
            15718137