MECHANISMS OF DNA REPAIR IN ACTIVE GENES

描述：本提案的主要目标是了解 细胞用来清除DNA损伤的分子机制。 选择性 从活性基因的转录链中去除DNA损伤，称为 转录偶联核苷酸切除修复（TCNR）可能是普遍存在的 并且已经被清楚地证明可以去除紫外线 诱导的环丁烷嘧啶二聚体。 这项研究的重点是 表征的机制，一般性和生物后果， 转录偶联修复 在E.大肠杆菌被选中是因为 我们用来鉴定所需基因的突变体的可用性 为了这个过程。 研究人员将继续在E.杆菌和 将补充这些研究与检查TCNR在人类细胞。 应采取的方法包括：（1）确定组件如何 错配修复影响核苷酸切除修复。 大肠杆菌使用 遗传和生物化学方法。 为了研究潜在的生化 错配修复的成分和 核苷酸切除修复，我们将尝试建立一个系统， 我们可以在E.体外培养大肠杆菌。 (2)确定突变 人类错配修复基因影响环丁烷嘧啶的去除 肿瘤细胞系和淋巴母细胞系中DHFR基因的二聚体 遗传性非息肉病性结直肠癌（HNPCC）患者。 如果 人类错配修复基因的突变也破坏了转录偶联蛋白， 修复，那么肿瘤的病因与突变不匹配有关 修复基因可能受到核苷酸切除修复缺陷的影响 和碱基切除修复，除了错配缺陷外， 纠正一下 (3)研究人员还将试图确定 编码E. 大肠杆菌RNA聚合酶显着减少核苷酸切除修复， 非转录DNA 这些突变体在表型上类似于人类干皮病 色素性C组细胞系。

DESCRIPTION: The broad objective of this proposal is to understand the molecular mechanisms cells use for removing DNA damage. The selective removal of DNA damage from the transcribed strands of active genes, termed transcription-coupled nucleotide excision repair (TCNR), may be ubiquitous and has been clearly demonstrated for the removal of ultraviolet light induced cyclobutane pyrimidine dimers. This research is focused on characterizing the mechanism, generality and biological consequences of transcription-coupled repair. Studies in E. Coli have been featured because of the availability of mutants that we have used to identify genes required for the process. The researchers will continue to study TCNR in E. Coli and will complement these studies with the examination of TCNR in human cells. Approaches to be taken include the following: (1) Determine how components of mismatch repair influence nucleotide excision repair inE. Coli using genetic and biochemical approaches. To study the potential biochemical interactions between components of mismatch repair and components of nucleotide excision repair, we will attempt to establish a system in which we can study TCNR in E. Coli in vitro. (2) Establish that mutations in human mismatch repair genes influence the removal of cyclobutane pyrimidine dimers from the DHFR gene in tumor cell lines and lymphoblastoid cell lines from patients with hereditary nonpolyposis colorectal carcinoma (HNPCC). If mutations in human mismatch repair genes also abolish transcription-coupled repair, then the etiology of tumors associated with mutations in mismatch repair genes may be influenced by deficiencies in nucleotide excision repair and base excision repair, in addition to the deficiency in mismatch correction. (3) The researchers will also attempt to determine the mechanism by which mutations in the gene encoding the beta subunit of the E. Coli RNA polymerase dramatically reduce nucleotide excision repair in nontranscribed DNA. These mutants pheontypically resemble human xeroderma pigmentosum group C cell lines.