PMID:18223657
| Citation |
Tanner, NA, Hamdan, SM, Jergic, S, Loscha, KV, Schaeffer, PM, Dixon, NE and van Oijen, AM (2008) Single-molecule studies of fork dynamics in Escherichia coli DNA replication. Nat. Struct. Mol. Biol. 15:170-6 |
|---|---|
| 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. |
| Links |
PubMed PMC2651573 Online version:10.1038/nsmb.1381 |
| Keywords |
DNA Polymerase III/metabolism; DNA Replication/physiology; DNA, Bacterial/metabolism; DnaB Helicases/metabolism; Endodeoxyribonucleases/metabolism; Escherichia coli/metabolism; Escherichia coli Proteins/metabolism; Exodeoxyribonucleases/metabolism; Kinetics; Models, Biological; Models, Molecular; Protein Binding |
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