Biochemical basis for dominant mutations in the Saccharomyces cerevisiae MSH6 gene

doi:10.1073/pnas.0510078103

Biochemical basis for dominant mutations in the Saccharomyces cerevisiae MSH6 gene

Departments of Medicine and Cellular and Molecular Medicine, and Cancer Center, Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0669

Contributed by Richard D. Kolodner, November 21, 2005

Abstract

Here, the ATP-binding, ATP hydrolysis, mispair-binding, sliding clamp formation, and Mlh1–Pms1 complex interaction properties of dominant mutant Msh2–Msh6 complexes have been characterized. The results demonstrate two mechanisms for dominance. In one, seen with the Msh6-S1036P and Msh6-G1067D mutant complexes, the mutant complex binds mispaired bases, is defective for ATP-induced sliding clamp formation and assembly of ternary complexes with Mlh1-Pms1, and occludes mispaired bases from other mismatch repair pathways. In the second, seen with the Msh6–G1142D complex, the mutant complex binds mispaired bases and is defective for ATP-induced sliding clamp formation but assembles ternary complexes with Mlh1–Pms1 that either occlude the mispaired base or prevent Mlh1–Pms1 from acting in alternate mismatch repair pathways.

Footnotes

↵ † To whom correspondence should be addressed. E-mail: rkolodner{at}ucsd.edu.
↵ * M.T.H. and M.L.M. contributed equally to this work.
Conflict of interest statement: No conflicts declared.
Abbreviations: ATPγS, adenosine 5′-[γ-thio]triphosphate; IPTG, isopropyl β-d-thiogalactoside; MMR, mismatch repair.