Single-stranded DNA-binding proteins (SSBs) support DNA replication by protecting single-stranded DNA from nucleolytic attack, preventing intra-strand pairing events and playing many other regulatory roles within the replisome. Recent developments in single-molecule approaches have led to a revised picture of the replisome that is much more complex in how it retains or recycles protein components. Here, we visualize how an in vitro reconstituted Escherichia coli replisome recruits SSB by relying on two different molecular mechanisms. Not only does it recruit new SSB molecules from solution to coat newly formed single-stranded DNA on the lagging strand, but it also internally recycles SSB from one Okazaki fragment to the next. We show that this internal transfer mechanism is balanced against recruitment from solution in a manner that is concentration dependent. By visualizing SSB dynamics in live cells, we show that both internal transfer and external exchange mechanisms are physiologically relevant.
|Original language||English (US)|
|Number of pages||13|
|Journal||Nucleic Acids Research|
|State||Published - Feb 15 2019|
Bibliographical noteKAUST Repository Item: Exported on 2021-03-12
Acknowledged KAUST grant number(s): OSR-2015-CRG4-2644
Acknowledgements: Research grants [DP150100956, DP180100858 to A.M.v.O., N.E.D.]; Australian Research Council, Australian Laureate Fellowship [FL140100027 to A.M.v.O.]; King Abdullah University of Science and Technology, Saudi Arabia [OSR-2015-CRG4-2644 to N.E.D., A.M.v.O.)]; Nederlandse Organisatie voor Wetenschap-pelijk Onderzoek [12CMCE03 to L.M.S.]. Funding for open access charge: Australian Research Council.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
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