DNA mismatch repair (MMR) is a conserved DNA repair process that corrects mistakes made during DNA replication.  Mutations in MMR proteins are found in a number of cancers, most notably Hereditary Non-Polyposis Colorectal Cancer.  Understanding the mechanism by which MMR proteins participate in repair (and how mutations found in cancer inactivate the repair pathway) is key in furthering our understanding of cancer.  Genetic and bulk biochemical studies have revealed the MMR pathway and identified the proteins involved, but the details of the dynamics of protein-protein and protein-DNA interactions remain elusive.  Even more elusive are conformational changes within the MMR proteins that facilitate the signaling required to transition from mismatch recognition to DNA repair. We are using single molecule FRET to understand the dynamics of the interactions between the yeast MMR proteins MutSa, MutLa and mismatched DNA. FRET pairs attached to the DNA reveal dynamic bending of DNA by MutSa.  In other experiments we want to use single molecule FRET between dyes attached to the damaged DNA and dyes on either MutSa or MutLa, which requires site-specific labeling of the protein.  Towards that end, we report progress using unnatural amino acid labeling and other approaches.

Single molecule studies of DNA mismatch repair protein dynamics

248th National Meeting (2014)

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