Yeast Rad17/Mec3/Ddc1: a sliding clamp for the DNA damage checkpoint.

The Saccharomyces cerevisiae Rad24 and Rad17 checkpoint proteins are part of an early response to DNA damage in a signal transduction pathway leading to cell cycle arrest. Rad24 interacts with the four small subunits of replication factor C (RFC) to form the RFC-Rad24 complex. Rad17 forms a complex with Mec3 ...
and Ddc1 (Rad1731) and shows structural similarities with the replication clamp PCNA. This parallelism with a clamp-clamp loader system that functions in DNA replication has led to the hypothesis that a similar clamp-clamp loader relationship exists for the DNA damage response system. We have purified the putative checkpoint clamp loader RFC-Rad24 and the putative clamp Rad1731 from a yeast overexpression system. Here, we provide experimental evidence that, indeed, the RFC-Rad24 clamp loader loads the Rad1731 clamp around partial duplex DNA in an ATP-dependent process. Furthermore, upon ATP hydrolysis, the Rad1731 clamp is released from the clamp loader and can slide across more than 1 kb of duplex DNA, a process which may be well suited for a search for damage. Rad1731 showed no detectable exonuclease activity.
Mesh Terms:
Adenosine Triphosphatases, Adenosine Triphosphate, Cell Cycle Proteins, Chromatography, Gel, DNA, DNA Damage, DNA-Binding Proteins, Electrophoresis, Polyacrylamide Gel, Hydrolysis, Nuclear Proteins, Phosphoproteins, Plasmids, Protein Binding, Replication Protein C, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Surface Plasmon Resonance, Time Factors
Proc. Natl. Acad. Sci. U.S.A.
Date: Mar. 04, 2003
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