Loading clamps for DNA replication and repair.
Sliding clamps and clamp loaders were initially identified as DNA polymerase processivity factors. Sliding clamps are ring-shaped protein complexes that encircle and slide along duplex DNA, and clamp loaders are enzymes that load these clamps onto DNA. When bound to a sliding clamp, DNA polymerases remain tightly associated with the template being copied, but are able to translocate along DNA at rates limited by rates of nucleotide incorporation. Many different enzymes required for DNA replication and repair use sliding clamps. Clamps not only increase the processivity of these enzymes, but may also serve as an attachment point to coordinate the activities of enzymes required for a given process. Clamp loaders are members of the AAA+ family of ATPases and use energy from ATP binding and hydrolysis to catalyze the mechanical reaction of loading clamps onto DNA. Many structural and functional features of clamps and clamp loaders are conserved across all domains of life. Here, the mechanism of clamp loading is reviewed by comparing features of prokaryotic and eukaryotic clamps and clamp loaders.
Bloom
Linda B
LB
Department of Biochemistry & Molecular Biology, University of Florida, Gainesville, FL 32610-0245, United States. lbloom@ufl.edu
D004247:DNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans
D004268:DNA-Binding Proteins; D004247:DNA