Frequent exchange of the DNA polymerase during bacterial chromosome replication

Autor: Thomas R Beattie, Nitin Kapadia, Emilien Nicolas, Stephan Uphoff, Adam JM Wollman, Mark C Leake, Rodrigo Reyes-Lamothe
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Zdroj: eLife, Vol 6 (2017)
Druh dokumentu: article
ISSN: 2050-084X
DOI: 10.7554/eLife.21763
Popis: 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. In vitro studies of reconstituted E. coli replisomes have attributed this remarkable processivity to the high stability of the replisome once assembled on DNA. 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.
Databáze: Directory of Open Access Journals