A mutation in the MSH6 subunit of the Saccharomyces cerevisiae MSH2-MSH6 complex disrupts mismatch recognition. |
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Authors: | J Bowers T Sokolsky T Quach E Alani |
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Affiliation: | Section of Genetics and Development, Cornell University, Ithaca, New York 14853-2703, USA. |
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Abstract: | In yeast, MSH2 interacts with MSH6 to repair base pair mismatches and single nucleotide insertion/deletion mismatches and with MSH3 to recognize small loop insertion/deletion mismatches. We identified a msh6 mutation (msh6-F337A) that when overexpressed in wild type strains conferred a defect in both MSH2-MSH6- and MSH2-MSH3-dependent mismatch repair pathways. Genetic analysis suggested that this phenotype was due to msh6-F337A sequestering MSH2 and preventing it from interacting with MSH3 and MSH6. In UV cross-linking, filter binding, and gel retardation assays, the MSH2-msh6-F337A complex displayed a mismatch recognition defect. These observations, in conjunction with ATPase and dissociation rate analysis, suggested that MSH2-msh6-F337A formed an unproductive complex that was unable to stably bind to mismatch DNA. |
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