Enzymology and Eukaryotic Mismatch Repair

酶学和真核错配修复

• 批准号: 6837609
• 负责人: PAUL LAWRENCE MODRICH
• 金额: $ 38.5万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-01-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6837609
• 关键词: Enzymology; Eukaryotic; Mismatch; Repair

EXCEED THE SPACE PROVIDED. Defects in the human mismatch repair system are the cause of hereditary nonpolyposis colon cancer and familial colon cancer, and have also been implicated in etiology of sporadic tumors. Inactivation of this pathway renders cells genetically unstable due to DNA replication errors, illegitimate recombination events, and failure to respond normally to certain DNA damaging agents, including several that are used as anti- tumor drugs. Despite the importance of this genetic stabilization system, our understanding of its molecular nature is limited. Although seven activities have been implicated in human strand-specific mismatch repair (MutS_, MutS_, MutLo_, PCNA, RPA, EXOI, and DNA polymerase $), these are not sufficient to reconstitute the reaction. A major goal for the requested extension of this project is the identification and isolation of other required activities. MutSo_ and MutL_ play key roles in the initiation of mismatch repair, but the molecular modes by which they interact with DNA and the roles of their nucleotide hydrolytic functions are not well defined and have been the subject of controversy. The second aim of this application addresses these questions, with emphasis on the protein oligomerization states involved in the interaction with DNA, and further clarification of the function of their ATPase centers as modulators of DNA-protein interaction. The nature of multi-protein and multi-protein-DNA assemblies involved in early stages of the mismatch repair reaction will also be examined. These studies will emphasize interactions of MutSo_ with MutLo_, MutS(_ with PCNA, and EXOI with MutSo_ and MutLa, as well as modulation of activated EXOI by RPA. The fourth line of proposed work addresses the role of the mismatch repair system and the BLM helicase in recombination fidelity. Illegitimate recombination events are elevated in mismatch repair-deficient and in BLM-deficient cells, and MutSo_ has been shown to modulate the activity of the BLM helicase. Consequently, we will ask whether these two systems function in a coordinated manner to suppress illegitimate recombination events. PERFORMANCE SITE ========================================Section End===========================================

超出提供的空间。人类错配修复系统的缺陷是遗传性非息肉病性结肠癌和家族性结肠癌的原因，也与散发性肿瘤的病因学有关。由于DNA复制错误、非法重组事件以及对某些DNA损伤剂(包括几种用作抗肿瘤药物的药物)的正常反应，这一途径的失活使细胞在遗传上不稳定。尽管这种遗传稳定系统很重要，但我们对其分子性质的了解是有限的。虽然已经有7种活性与人类链特异性错配修复有关(MutS_、MutS_、MutLo_、增殖细胞核抗原、RPA、EXOI和DNA聚合酶)，但这些都不足以重建反应。请求延长该项目的一个主要目标是确定和隔离其他所需活动。MutSo和MutL在错配修复的启动中起着关键作用，但它们与DNA相互作用的分子模式及其核苷酸水解性功能的作用尚不清楚，一直存在争议。本申请的第二个目的是解决这些问题，重点是与DNA相互作用中涉及的蛋白质齐聚状态，并进一步阐明它们的ATPase中心作为DNA-蛋白质相互作用的调节器的功能。还将研究错配修复反应早期阶段涉及的多蛋白质和多蛋白质-DNA组件的性质。这些研究将侧重于Mutso_与MutLo_，MutS(_)与增殖细胞核抗原，以及EXOI与Mutso_和Mutla的相互作用，以及RPA对激活的EXOI的调控。建议的第四行工作涉及错配修复系统和BLM解旋酶在重组保真度中的作用。在错配修复缺陷和BLM缺陷的细胞中，不合法的重组事件增加，并且Mutso_已被证明调节BLM解旋酶的活性。因此，我们会问，这两个系统是否以协调的方式发挥作用，以抑制非法重组事件。表演网站========================================Section End===========================================