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Title: Replication fork collisions cause pathological chromosomal amplification in cells lacking RecG DNA translocase
Authors: Upton, AL
Lloyd, RG
Keywords: Chromosomes;DNA replication;RecG DNA;Bacteria
Issue Date: 2009
Publisher: Wiley-Blackwell
Citation: Molecular Microbiology, 74(4), 940 - 955, 2009
Abstract: Duplication and transmission of chromosomes require precise control of chromosome replication and segregation. Here we present evidence that RecG is a major factor influencing these processes in bacteria. We show that the extensive DnaA-independent stable DNA replication observed without RecG can lead to replication of any area of the chromosome. This replication is further elevated following irradiation with UV light and appears to be perpetuated by secondary events that continue long after the elimination of UV lesions. The resulting pathological cascade is associated with an increased number of replication forks traversing the chromosome, sometimes with extensive regional amplification of the chromosome, and with the accumulation of highly branched DNA intermediates containing few Holliday junctions. We propose that the cascade is triggered by replication fork collisions that generate 3′ single-strand DNA flaps, providing sites for PriA to initiate re-replication of the DNA and thus to generate linear duplexes that provoke recombination, allowing priming of even further replication. Our results shed light on why termination of replication in bacteria is normally limited to a single encounter of two forks and carefully orchestrated within a restricted area, and explain how a system of multiple forks and random termination can operate in eukaryotes.
Description: This is an open access article, shared under a Creative Commons licence. Copyright © 2009 The Authors.
ISSN: 0950-382X
Appears in Collections:Biological Sciences
Dept of Life Sciences Research Papers

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