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The 2B subdomain of Rep helicase links translocation along DNA with protein displacement

Research output: Contribution to journalArticle (Academic Journal)

Original languageEnglish
Article numbergky673
Pages (from-to)8917-8925
Number of pages9
JournalNucleic Acids Research
Issue number17
Early online date28 Jul 2018
DateAccepted/In press - 17 Jul 2018
DateE-pub ahead of print - 28 Jul 2018
DatePublished (current) - 28 Sep 2018


Helicases catalyse DNA and RNA strand separation. Proteins bound to the nucleic acid must also be displaced in order to unwind DNA. This is exemplified by accessory helicases that clear protein barriers from DNA ahead of advancing replication forks. How helicases catalyse DNA unwinding is increasingly well understood but how protein displacement is achieved is unclear. Escherichia coli Rep accessory replicative helicase lacking one of its four subdomains, 2B, has been shown to be hyperactivated for DNA unwinding in vitro but we show here that RepΔ2B is, in contrast, deficient in displacing proteins from DNA. This defect correlates with an inability to promote replication of protein-bound DNA in vitro and lack of accessory helicase function in vivo. Defective protein displacement is manifested on double-stranded and single-stranded DNA. Thus binding and distortion of duplex DNA by the 2B subdomain ahead of the helicase is not the missing function responsible for this deficiency. These data demonstrate that protein displacement from DNA is not simply achieved by helicase translocation alone. They also imply that helicases may have evolved different specific features to optimise DNA unwinding and protein displacement, both of which are now recognised as key functions in all aspects of nucleic acid metabolism.

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