Mismatch Repair Interactions

University Of Calif-Lawrenc Berkeley Lab, Berkeley CA

Investigators

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Abstract

The Project (Mismatch Repair Interactions) integrates into the SBDR Program Project by focusing upon early[unreadable] responses to mutagenic mispaired bases and DNA adducts, including adducts made by chemotherapeutic[unreadable] agents. Mismatch repair is a major contributor to genome stability; defects in the mammalian pathway are[unreadable] associated with a strong predisposition to tumor development and inherited mutations in mismatch repair[unreadable] genes underlie one of the most prevalent inherited cancer susceptibility syndromes known. Despite the[unreadable] importance of this system in avoiding mutation, our understanding of its molecular nature is limited. The[unreadable] goals of this project are to establish the conformations and structures of multi-protein and multi-protein-DNA[unreadable] complexes that are the key intermediates in triggering the MutSa- and MutLa-dependent responses to[unreadable] mismatched base pairs and certain types of DNA damage. To accomplish this, our aims are four-fold: (1)[unreadable] The conformations and dynamics of multi-protein and multi-protein DNA assemblies involved in the initiation[unreadable] step of mismatch repair will be addressed by small angle X-ray scattering. These and other structural[unreadable] studies will exploit the high temporal resolution of the Structural Cell Biology (SCB) Synchrotron Beamline[unreadable] and the SCB Core. (2) The molecular basis for the recognition of base-base mispairs, insertion/deletion[unreadable] mispairs, and damaged DNA substrates will be addressed by X-ray crystallography. (3) Since the initiation of[unreadable] mismatch repair depends on assembly of multi-protein-DNA complexes (MutSa.MutLa.PCNA.DNA in the[unreadable] eukaryotic reaction) these multi-protein and multi-protein-DNA assemblies will be examined using X-ray[unreadable] crystallography. (4) The structural studies above will reveal residues at protein-protein interfaces as well as[unreadable] those that may be involved in conformational transitions; the significance of these residues will be subjected[unreadable] to biological validation by analysis of the phenotypic consequences of genetic alteration of these residues[unreadable] and by examination of selected mutant proteins at the biochemical level.