Mechanism of the initial steps in transcription-coupled DNA repair (TCR)

转录偶联 DNA 修复 (TCR) 初始步骤的机制

• 批准号: 8349391
• 负责人: MIKHAIL KASHLEV
• 金额: $ 51.94万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8349391
• 关键词: Active Sites; Address; Binding; Chromatin; Cisplatin; Complex; Coupled; DNA; DNA Damage; DNA Polymerase II; DNA Repair; DNA Repair Pathway; DNA lesion; DNA-dependent ATPase; Development; Enzymes; Escherichia coli; Eukaryota; Event; Excision; Family; Genes; Genetic; Genetic Transcription; Goals; Homologous Gene; In Vitro; Investigation; Lead; Lesion; Location; Mammalian Cell; Mediating; Molecular; Nature; Nucleosomes; Nucleotide Excision Repair; Pathway interactions; Play; Polymerase; Positioning Attribute; Proteins; Protocols documentation; Pyrimidine Dimers; Recombinant DNA; Recruitment Activity; Research; Resistance; Role; SAGA; Saccharomyces cerevisiae; Signal Transduction; Site; System; Thymidine; Transcription Elongation; Transcription Initiation; Transcription-Coupled Repair; Type II Cockayne Syndrome; UV induced DNA damage; Ubiquitination; Variant; Yeasts; adduct; analog; base; chemotherapeutic agent; crosslink; dimer; genetic analysis; helicase; histone modification; insight; member; mutant; novel; originality; repaired; response; success; transcription factor S-II; transcription factor TFIIE; transcription factor TFIIH; tumor; ubiquitin ligase

The mechanism of TCR initiation in S. cerevisiae is distinct from the TCR initiation in mammalian cells. While deletion of the Cockayne Syndrome Group B gene severely inhibits TCR in the mammalian cells, deletion of its yeast homologue Rad26 only slightly impairs the TCR. Genetic analyses strongly suggest two alternative TCR subpathways in yeast. The first, dominant pathway is probably initiated by Pol II interaction with Rad26, and is dependent on a non-essential Pol II subunit Rpb4. The second TCR pathway becomes prominent in the absence of Rpb4, and is dependent on another non-essential Pol II subunit Rpb9. The mechanism of the Rpb9-mediated TCR pathway is not well understood. Its investigation by genetic means has been hampered by the lack of the RPB4/RPB9 double deletion mutant, which is likely to be lethal. Analysis of the Rpb9-dependent pathway in yeast may provide important insights into the Pol II-related events during TCR. The location of the Rpb9 subunit on the perimeter of Pol II suggests its possible function in recruiting NER factors to the damaged site. Rpb9 is involved in multiple-transcription related functions such as transcription initiation (selection of the start site), transcription elongation, and recently in ubiquitination and degradation of rpb1 in response to UV-induced DNA damage. This subunit also interacts with a plethora of factors involved in transcription elongation and histone modification (like TFIIS, TFIIE, and SAGA). Which of these factors act as a Rad26 analogue in the Rpb9-mediated TCR pathway remains to be identified.

对S.酿酒酵母中的TCR起始不同于哺乳动物细胞中的TCR起始。虽然Cockayne综合征组B基因的缺失严重抑制哺乳动物细胞中的TCR，但其酵母同源物Rad 26的缺失仅轻微损害TCR。遗传分析强烈提示酵母中有两种替代TCR子途径。第一，显性途径可能是由Pol II与Rad 26相互作用启动的，并且依赖于非必需的Pol II亚基Rpb 4。第二TCR途径在不存在Rpb 4的情况下变得突出，并且依赖于另一个非必需Pol II亚基Rpb 9。Rpb 9介导的TCR途径的机制还不清楚。由于缺乏可能致命的RPB 4/RPB 9双缺失突变体，通过遗传手段对其进行的研究受到阻碍。酵母中Rpb 9依赖性途径的分析可能为TCR期间Pol II相关事件提供重要见解。Rpb 9亚基在Pol II周边的位置表明其可能的功能是将NER因子募集到受损部位。Rpb 9参与多种转录相关功能，如转录起始（起始位点的选择），转录延伸，以及最近参与响应UV诱导的DNA损伤的rpb 1的泛素化和降解。该亚基还与参与转录延伸和组蛋白修饰的大量因子（如TFIIS、TFIIE和佐贺）相互作用。这些因子中的哪一个在Rpb 9介导的TCR途径中充当Rad 26类似物仍有待鉴定。