Mismatch Repair Interactions

该项目（失配修复相互作用）通过关注早期 对致突变错配碱基和DNA加合物的反应，包括化疗药物产生的加合物 剂.错配修复是基因组稳定性的主要贡献者;哺乳动物途径中的缺陷是 与肿瘤发展的强烈倾向和错配修复中的遗传突变相关 基因是已知的最普遍的遗传性癌症易感性综合征之一的基础。尽管 尽管该系统在避免突变方面具有重要意义，但我们对其分子性质的理解是有限的。的 本项目的目标是建立多蛋白和多蛋白-DNA的构象和结构 复合物是触发MutSa和MutLa依赖性反应的关键中间体， 错配的碱基对和某些类型的DNA损伤为了实现这一目标，我们有四个目标：（1） 多蛋白质和多蛋白质DNA组装体的构象和动力学 失配修复步骤将通过小角度X射线散射来解决。这些和其他结构 研究将利用同步加速器光束线的高时间分辨率 和SCB核心(2)识别碱基错配、插入/缺失的分子基础 错配和受损的DNA底物将通过X射线晶体学来解决。(3)从发起所 错配修复依赖于多蛋白质-DNA复合物的组装（MutSa、MutLa、PCNA、 这些多蛋白质和多蛋白质-DNA组装体将使用X射线进行检查 结晶学(4)上述结构研究将揭示蛋白质-蛋白质界面的残基以及 那些可能参与构象转变的残基;这些残基的重要性将受到 通过分析这些残基遗传改变的表型结果进行生物学验证 并通过在生物化学水平上检测所选的突变蛋白质。

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