Frequent exchange of the DNA polymerase during bacterial chromosome replication
- McGill University, Canada
- Fast Track Diagnostics Luxembourg S.à.r.l, Luxembourg
- University of Oxford, United Kingdom
- University of York, United Kingdom
Abstract
The replisome is a multiprotein machine that carries out DNA replication. In Escherichia coli, a single pair of replisomes is responsible for duplicating the entire 4.6 Mbp circular chromosome (Beattie and Reyes-Lamothe, 2015). In vitro studies of reconstituted E. coli replisomes have attributed this remarkable processivity to the high stability of the replisome once assembled on DNA (Tanner et al., 2011, Yao et al., 2009, Kim et al., 1996b). By examining replisomes in live E. coli with fluorescence microscopy, we found that the Pol III* subassembly frequently disengages from the replisome during DNA synthesis and exchanges with free copies from solution. In contrast, the DnaB helicase associates stably with the replication fork, providing the molecular basis for how the E. coli replisome can maintain high processivity and yet possess the flexibility to bypass obstructions in template DNA. Our data challenges the widely-accepted semi-discontinuous model of chromosomal replication, instead supporting a fully discontinuous mechanism in which synthesis of both leading and lagging strands is frequently interrupted.
Article and author information
Author details
Rodrigo Reyes-Lamothe
Funding
Natural Sciences and Engineering Research Council of Canada (Discovery Grant,435521-2013)
- Thomas R Beattie
- Nitin Kapadia
- Rodrigo Reyes-Lamothe
Canada Research Chairs (Tier II,950-228994)
- Rodrigo Reyes-Lamothe
Canadian Institutes of Health Research (Operating Grant,142473)
- Thomas R Beattie
- Nitin Kapadia
- Rodrigo Reyes-Lamothe
Canada Foundation for Innovation (Leaders Oportunity Fund,228994)
- Thomas R Beattie
- Nitin Kapadia
- Rodrigo Reyes-Lamothe
Wellcome (Junior Research Fellowship)
- Stephan Uphoff
Biotechnology and Biological Sciences Research Council (BBSRC# BB/N006453/1)
- Adam JM Wollman
- Mark C Leake
Medical Research Council (MRC# MR/K01580X/1)
- Adam JM Wollman
- Mark C Leake
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2017, Beattie et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Frequent exchange of the DNA polymerase during bacterial chromosome replication
eLife 6:e21763.
https://doi.org/10.7554/eLife.21763
