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Cell. 2017 Jun 15;169(7):1201-1213.e17. doi: 10.1016/j.cell.2017.05.041.

Independent and Stochastic Action of DNA Polymerases in the Replisome.

Author information

1
Department of Microbiology and Molecular Genetics and Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
2
Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA. Electronic address: kmarians@sloankettering.edu.
3
Department of Microbiology and Molecular Genetics and Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA. Electronic address: sckowalczykowski@ucdavis.edu.

Abstract

It has been assumed that DNA synthesis by the leading- and lagging-strand polymerases in the replisome must be coordinated to avoid the formation of significant gaps in the nascent strands. Using real-time single-molecule analysis, we establish that leading- and lagging-strand DNA polymerases function independently within a single replisome. Although average rates of DNA synthesis on leading and lagging strands are similar, individual trajectories of both DNA polymerases display stochastically switchable rates of synthesis interspersed with distinct pauses. DNA unwinding by the replicative helicase may continue during such pauses, but a self-governing mechanism, where helicase speed is reduced by ∼80%, permits recoupling of polymerase to helicase. These features imply a more dynamic, kinetically discontinuous replication process, wherein contacts within the replisome are continually broken and reformed. We conclude that the stochastic behavior of replisome components ensures complete DNA duplication without requiring coordination of leading- and lagging-strand synthesis. PAPERCLIP.

KEYWORDS:

DNA polymerase; DNA replication; replication fork coordination; replication fork progression; single-molecule analysis

PMID:
28622507
PMCID:
PMC5548433
DOI:
10.1016/j.cell.2017.05.041
[Indexed for MEDLINE]
Free PMC Article

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