MECHANISMS OF DNA REPAIR IN ACTIVE GENES

活性基因中的 DNA 修复机制

• 批准号: 2444781
• 负责人: ISABEL W MELLON
• 金额: $ 18.94万
• 依托单位: UNIVERSITY OF KENTUCKY
• 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 1999-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2444781
• 关键词: DNA damage; DNA directed RNA polymerase; DNA repair; Escherichia coli; alleles; biochemistry; gene mutation; genetic transcription; human genetic material tag; human tissue; lac operon; mutant; nucleotides; plasmids; protein structure; pyrimidine dimers; radiation genetics; tissue /cell culture; ultraviolet radiation

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.

描述：该提案的总体目标是了解 细胞用于消除 DNA 损伤的分子机制。 选择性的 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）可能无处不在 并已被清楚地证明可以消除紫外线 诱导的环丁烷嘧啶二聚体。 这项研究的重点是 描述其机制、一般性和生物学后果 转录耦合修复。 大肠杆菌研究之所以受到关注是因为 我们用来鉴定所需基因的突变体的可用性 对于这个过程。 研究人员将继续研究大肠杆菌中的 TCNR 将通过检测人体细胞中的 TCNR 来补充这些研究。 采取的方法包括： (1) 确定组件如何 错配修复影响大肠杆菌中的核苷酸切除修复。 大肠杆菌使用 遗传和生化方法。 研究潜在的生化作用 错配修复成分和错配修复成分之间的相互作用 核苷酸切除修复，我们将尝试建立一个系统，其中 我们可以在体外研究大肠杆菌中的TCNR。 (2) 确定突变 人类错配修复基因影响环丁烷嘧啶的去除 肿瘤细胞系和类淋巴母细胞系中 DHFR 基因的二聚体 来自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会消除转录耦合 修复，然后是与错配突变相关的肿瘤病因学 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，除了错配的缺陷之外 更正。 (3) 研究人员还将尝试确定 编码大肠杆菌β亚基的基因发生突变的机制。 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C组细胞系。