A molecular switch in a replication machine defined by an internal competition for protein rings.
Replication machines use ring-shaped clamps that encircle DNA to tether the polymerase to the chromosome. The clamp is assembled on DNA by a clamp loader. This report shows that the polymerase and clamp loader coordinate their actions with the clamp by competing for it through overlapping binding sites. The competition is modulated by DNA. In the absence of DNA, the clamp associates with the clamp loader. But after the clamp is placed on DNA, the polymerase develops a tight grip on the clamp and out-competes the clamp loader. After replication of the template, the polymerase looses affinity for the clamp. Now the clamp loader regains access to the clamp and removes it from DNA thus recycling it for future use.
Naktinis
V
V
Microbiology Department, Howard Hughes Medical Institute, Cornell University Medical College, New York, New York 10021, USA.
Turner
J
J
O'Donnell
M
M
D001667:Binding, Competitive; D004247:DNA / Q000378:metabolism; D004258:DNA Polymerase III / Q000032:analysis / Q000378:metabolism / Q000648:ultrastructure*; D004261:DNA Replication / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000032:analysis / Q000378:metabolism; D016297:Mutagenesis, Site-Directed
D004268:DNA-Binding Proteins; D004247:DNA; D004258:DNA Polymerase III