DNA Repair Genes and Proteins of the RAD52 Group

 描述（由申请人提供）：在模型真核生物酿酒酵母中进行的研究表明，同源重组（HR）是消除电离辐射诱导的DNA双链断裂（DSB）的主要机制，或与受损的DNA复制叉相关。在修复过程中，DNA断裂的末端被核裂解切除以产生3' ssDNA尾，其被HR因子结合。这样形成的核蛋白复合物然后进行搜索以定位未受损的DNA同源物，并催化与同源物形成称为D环的DNA接头。D-环的解析可以通过至少三种机制上不同的途径进行，其中两种仅产生非交换重组体，因此更擅长基因组保存，其余途径能够频繁产生交换。由RAD 52上位性组的进化保守基因编码的蛋白质催化HR反应。我们的研究提供了深入了解的机制基础的人力资源机制，窝藏这个基因组的蛋白质。在这个更新项目中，生物化学，遗传学和其他基于细胞的方法的组合将被用于（i）定义DSB末端切除的DNA马达驱动路径的作用机制及其与酵母和人类细胞中的Exo 1介导的切除的功能串扰，以及（ii）描绘保守的Rad 51旁系同源物在Rad 51-ssDNA核蛋白丝组装中的作用。从我们的努力的结果将使我们能够制定详细的模型，以阐明在真核生物的HR机制。鉴于HR介导的染色体损伤修复在肿瘤抑制中的重要性，我们的工作与癌症生物学也有直接的密切关系。

 DESCRIPTION (provided by applicant): Studies in the model eukaryote Saccharomyces cerevisiae have revealed that homologous recombination (HR) provides a major mechanism for eliminating DNA double-stranded breaks (DSBs) induced by ionizing radiation or are associated with injured DNA replication forks. During the repair process, the ends of the DNA breaks are resected nucleolytically to yield 3' ssDNA tails, which are bound by HR factors. The nucleoprotein complex thus formed then conducts a search to locate an undamaged DNA homolog, and catalyzes the formation of a DNA joint, called D-loop, with the homolog. Resolution of the D-loop can proceed via at least three mechanistically distinct pathways, two of which generate only non-crossover recombinants and are therefore more adept at genome preservation, with the remaining pathway being able to produce crossovers frequently. Proteins encoded by evolutionarily conserved genes of the RAD52 epistasis group catalyze the HR reaction. Our studies have provided insights into the mechanistic underpinnings of the HR machinery that harbors proteins of this gene group. In this renewal project, a combination of biochemical, genetic, and other cell-based approaches will be employed to (i) define the mechanism of action of the DNA motor-driven path of DSB end resection and its functional crosstalk with Exo1-mediated resection in both yeast and human cells, and (ii) delineate the roles that the conserved Rad51 paralogs fulfill in the assembly of Rad51-ssDNA nucleoprotein filaments. The results from our endeavors will allow us to formulate detailed models to elucidate HR mechanisms in eukaryotes. Given the importance of HR-mediated chromosome damage repair in tumor suppression, our work also has direct, strong relevance to cancer biology.