IUBMB Enzyme Nomenclature


Accepted name: DNA 5'-3' helicase

Reaction: Couples ATP hydrolysis with the unwinding of duplex DNA at the replication fork by translocating in the 5'-3' direction. This creates two antiparallel DNA single strands (ssDNA). The leading ssDNA polymer is the template for DNA polymerase III holoenzyme which synthesizes a continuous strand.

Other name(s): DnaB helicase; replication fork helicase; 5' to 3' DNA helicase; BACH1 helicase; BcMCM; BLM protein; BRCA1-associated C-terminal helicase; CeWRN-1; Dbp9p; DNA helicase A; DNA helicase E; DNA helicase II; DNA helicase III; DNA helicase VI; dnaB (gene name); DnaB helicase E1; helicase HDH IV; Hel E; helicase DnaB; helicase domain of bacteriophage T7 gene 4 protein helicase; PcrA helicase; hHcsA; Hmi1p; hPif1; MCM helicase; MCM protein; MPH1; PcrA; PfDH A; Pfh1p; PIF1; replicative DNA helicase

Systematic name: DNA 5'-3' helicase (ATP-hydrolysing)

Comments: The activity is stimulated by DNA polymerase III. As the lagging ssDNA is created, it becomes coated with S Single-Stranded DNA Binding protein (SSB). Once every 500-2000 nucleotides, primase is stimulated by DnaB helicase to synthesize a primer at the replication fork. This primer is elongated by the lagging strand half of DNA polymerase III holoenzyme.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number:


1. Lohman, T.M. Helicase-catalyzed DNA unwinding. J. Biol. Chem. 268 (1993) 2269-2272. [PMID: 8381400]

2. Jezewska, M.J. and Bujalowski, W. Global conformational transitions in Escherichia coli primary replicative helicase DnaB protein induced by ATP, ADP, and single-stranded DNA binding. Multiple conformational states of the helicase hexamer. J. Biol. Chem. 271 (1996) 4261-4265. [PMID: 8626772]

3. Ivessa, A.S., Zhou, J.Q., Schulz, V.P., Monson, E.K. and Zakian, V.A. Saccharomyces Rrm3p, a 5' to 3' DNA helicase that promotes replication fork progression through telomeric and subtelomeric DNA. Genes Dev. 16 (2002) 1383-1396. [PMID: 12050116]

4. Zhou, J.Q., Qi, H., Schulz, V.P., Mateyak, M.K., Monson, E.K. and Zakian, V.A. Schizosaccharomyces pombe pfh1+ encodes an essential 5' to 3' DNA helicase that is a member of the PIF1 subfamily of DNA helicases. Mol. Biol. Cell 13 (2002) 2180-2191. [PMID: 12058079]

5. Ivanov, K.A. and Ziebuhr, J. Human coronavirus 229E nonstructural protein 13: characterization of duplex-unwinding, nucleoside triphosphatase, and RNA 5'-triphosphatase activities. J. Virol. 78 (2004) 7833-7838. [PMID: 15220459]

6. Toseland, C.P. and Webb, M.R. ATPase mechanism of the 5'-3' DNA helicase, RecD2: evidence for a pre-hydrolysis conformation change. J. Biol. Chem. 288 (2013) 25183-25193. [PMID: 23839989]

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