MECHANISMS OF DNA REPAIR IN ACTIVE GENES

我们的长期目标是了解细胞使用的分子机制 用于消除DNA损伤。我们最近揭示了DNA的一个新特征 修复；紫外光诱导的嘧啶二聚体被选择性移除 从哺乳动物细胞中活性基因的转录DNA链和E. Coli.现在的努力将集中在表征链的机制- 专门的修理。在大肠杆菌中的研究将被作为特色，因为 遗传和生化工具的可用性。 将采取的方法包括：修复乳糖操纵子 将在相关突变体中进行研究，以确定链- 可能机制的具体修复和测试模型。转录在 将对操纵子进行测量，以检验链特定的假设 修复对紫外线照射后的细胞存活很重要，因为它有助于 保持关键文本的水平。转录的影响 修复率操纵子内的修复位置，以及 清除化学损害将进行研究，以检验以下假设 病变阻断的RNA聚合酶复合体作为链- 专门的修理。核糖体和转移RNA基因的修复将 研究以确定链特异性修复是否受 核糖核酸转录过程中核糖核酸的加工或构象模型 将使用纯化的核苷酸在体外测试链特异性修复 切除修复蛋白。 我们的计划是确定参与者并学习管理规则 在大肠杆菌中的链特异性修复。在该系统中获得的结果将 然后被用来指导我们在其他系统中的调查。

Our long-term objective is to understand the molecular mechanisms cells use for removing DNA damage. We have recently revealed a novel feature of DNA repair; ultraviolet light-induced pyrimidine dimers are selectively removed from the transcribed DNA strands of active gene in mammalian cells and E. coli. Efforts will now focus on characterizing the mechanism of strand- specific repair. Studies in E. coli will be featured because of the availability of genetic and biochemical tools. Approaches to be taken include the following: Repair of the lactose operon will be studied in relevant mutants to identify genes required for strand- specific repair and test models of possible mechanisms. Transcription in the operon will be measured to test the hypothesis that strand-specific repair is important for cell survival after UV-irradiation because it helps maintain levels of critical transcripts. The influence of transcription rates on repair rates the location of repair within the operon, and the removal of chemical damage will be studied to test the hypothesis that lesion-blocked RNA polymerase complex serves as a signal for strand- specific repair. Repair of ribosomal and transfer RNA genes will be studied to determine if strand-specific repair is influenced by the processing or conformation of the RNA as it is being transcribed. Models of strand-specific repair will be tested in vitro using purified nucleotide excision repair proteins. Our plan is to identify the participants and learn the rules that govern strand-specific repair in E. coli. Results obtained in this system will then be used to direct our investigation in other systems.