STRUCTURAL STUDIES OF DNA REPAIR PROTEINS

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 TEL2是一种保守的蛋白质，对酵母的生存是必不可少的。由于TEL2在不同生物体中的许多明显不重叠的功能，确定TEL2的确切作用变得复杂。除了在酿酒酵母中维持端粒长度外，它还在裂殖酵母Pombe和人类中的DNA复制检查点发挥作用，将细胞分裂的开始与DNA的成功复制结合在一起。然而，在线虫中，CLK-2/rad-5(线虫中的TEL2同源基因)的亚型等位基因(编码的蛋白质与野生型等位基因相比功能减弱的亚型)不仅可以在DNA复制过程中造成压力和对DNA双链断裂高度敏感，而且还可以延长寿命，降低包括胚胎和胚胎后发育和繁殖在内的许多生理过程的频率。通过对TEL2缺失小鼠细胞表型的系统分析和生化蛋白相互作用的研究，确定了TEL2与所有6个哺乳动物磷脂酰肌醇3-激酶相关蛋白激酶(PIKKs)直接相互作用。TEL2的缺失大大降低了小鼠细胞中所有PIKK的表达水平，影响了它们的功能。由于最近在分裂酵母中也观察到了TEL2和PIKKs之间的直接物理联系，所以TEL2作为这些激酶的稳定器的功能也可能是保守的。这些结果为哺乳动物TEL2及其同源基因的所有已报道功能提供了一个统一的模型。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Tel2 is a well-conserved protein that is essential for yeast viability. Determining the precise role of Tel2 has been complicated by its many apparently nonoverlapping functions reported in various organisms. In addition to maintaining telomere length in S. cerevisiae, it functions in the DNA replication checkpoint in the fission yeast Schizosaccharomyces pombe and in humans, coupling the onset of cell division with the successful replication of DNA. In the nematode Caenorhabditis elegans, however, hypomorphic alleles (forms of agene in which the encoded protein has reduced function compared with the wild type allele) of clk-2/rad-5 (the TEL2 ortholog in C. elegans) not only can cause stress during DNA replication and hypersensitivity to DNA double-strand breaks, but also can increase life span and reduce the rate of numerous physiological processes, including embryonic and postembryonic development, and reproduction. Through systematic analysis of the phenotype of Tel2-null mouse cells and biochemical protein interaction studies, it was determined that TEL2 directly interacts with all six of the mammalian phosphatidylinositol3-kinaserelated protein kinases (PIKKs). Absence of TEL2 substantially reduced the expression level of all PIKKs in mouse cells, impinging on their function. Because a direct physical association between Tel2 and PIKKs was also recently observed in fission yeast, the function of Tel2 as a stabilizer of these kinases may also be conserved. These results provide a unifying model for all the reported functions of mammalian Tel2 and its orthologs.