Coupling of a replicative polymerase and helicase: a tau-DnaB interaction mediates rapid replication fork movement.
The E. coli replication fork synthesizes DNA at the rate of nearly 1000 nt/s. We show here that an interaction between the tau subunit of the replicative polymerase (the DNA polymerase III holoenzyme) and the replication fork DNA helicase (DnaB) is required to mediate this high rate of replication fork movement. In the absence of this interaction, the polymerase follows behind the helicase at a rate equal to the slow (approximately 35 nt/s) unwinding rate of the helicase alone, whereas upon establishing a tau-DnaB contact, DnaB becomes a more effective helicase, increasing its translocation rate by more than 10-fold. This finding establishes the existence of both a physical and communications link between the two major replication machines in the replisome: the DNA polymerase and the primosome.
Kim
S
S
Graduate Program in Molecular Biology, Cornell University Graduate School of Medical Sciences, New York 10021, USA.
Dallmann
H G
HG
McHenry
C S
CS
Marians
K J
KJ
D001426:Bacterial Proteins / Q000235:genetics*; D004265:DNA Helicases / Q000235:genetics*; D004258:DNA Polymerase III / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D004261:DNA Replication / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D053488:DnaB Helicases; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics
D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D004258:DNA Polymerase III; D004265:DNA Helicases; D053488:DnaB Helicases