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- Title
Single-molecule studies of fork dynamics in Escherichia coli DNA replication.
- Authors
Tanner, Nathan A; Hamdan, Samir M; Jergic, Slobodan; Loscha, Karin V; Schaeffer, Patrick M; Dixon, Nicholas E; van Oijen, Antoine M
- Abstract
We present single-molecule studies of the Escherichia coli replication machinery. We visualize individual E. coli DNA polymerase III (Pol III) holoenzymes engaging in primer extension and leading-strand synthesis. When coupled to the replicative helicase DnaB, Pol III mediates leading-strand synthesis with a processivity of 10.5 kilobases (kb), eight-fold higher than that by Pol III alone. Addition of the primase DnaG causes a three-fold reduction in the processivity of leading-strand synthesis, an effect dependent upon the DnaB-DnaG protein-protein interaction rather than primase activity. A single-molecule analysis of the replication kinetics with varying DnaG concentrations indicates that a cooperative binding of two or three DnaG monomers to DnaB halts synthesis. Modulation of DnaB helicase activity through the interaction with DnaG suggests a mechanism that prevents leading-strand synthesis from outpacing lagging-strand synthesis during slow primer synthesis on the lagging strand.
- Publication
Nature structural & molecular biology, 2008, Vol 15, Issue 2, p170
- ISSN
1545-9985
- Publication type
Journal Article
- DOI
10.1038/nsmb.1381