Single-molecule analysis reveals that the lagging strand increases replisome processivity but slows replication fork progression.
Single-molecule techniques are developed to examine mechanistic features of individual E. coli replisomes during synthesis of long DNA molecules. We find that single replisomes exhibit constant rates of fork movement, but the rates of different replisomes vary over a surprisingly wide range. Interestingly, lagging strand synthesis decreases the rate of the leading strand, suggesting that lagging strand operations exert a drag on replication fork progression. The opposite is true for processivity. The lagging strand significantly increases the processivity of the replisome, possibly reflecting the increased grip to DNA provided by 2 DNA polymerases anchored to sliding clamps on both the leading and lagging strands.
Yao
Nina Y
NY
Howard Hughes Medical Institute, Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Georgescu
Roxana E
RE
Finkelstein
Jeff
J
O'Donnell
Michael E
ME
D004258:DNA Polymerase III / Q000378:metabolism; D004261:DNA Replication; D004270:DNA, Circular / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004058:Diffusion; D053488:DnaB Helicases / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D008051:Lipid Bilayers / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism*; D000099272:Replisomes
D004258:DNA Polymerase III; D004270:DNA, Circular; D004259:DNA-Directed DNA Polymerase; D053488:DnaB Helicases; D008051:Lipid Bilayers; D009097:Multienzyme Complexes; D000099272:Replisomes; C506730:dnaB protein, E coli