RECOGNITION AND REPAIR OF UV DAMAGE TO HUMAN DNA

患有遗传性疾病着色性干皮病的人 (XP)缺乏DNA的核苷酸切除修复（NER）， 暴露后致癌概率高于平均人群 紫外线照射。NER是一种主要的细胞生物防御系统， 由于紫外线照射诱导的大体积损伤的形成而导致的DNA损伤， 环境遗传毒性化学物质和致癌物质。尽管， 普遍认为DNA损伤识别在NER中起着核心作用， DNA损伤过程的分子和热力学细节仍然主要 不清楚，也没有系统地研究使用生物化学严格 接近。此外，损伤识别蛋白XPA，RPA， 而XPC-HR 23 B一直备受争议。本研究的长期目标是 了解紫外线诱导或相关的分子和生物化学细节 人NER蛋白对DNA损伤的识别和修复， 这些关系对损伤诱导突变的影响， 致癌作用为了更系统更精确地了解DNA损伤 通过人类NER的识别和修复，将解决以下问题： 损伤识别的层次是什么，损伤是如何动态变化的 在逐步识别机制中处理？什么结构和化学 DNA螺旋的改变是通过特定的修复蛋白来识别的。 识别步骤？识别的分子结构是什么 中间体？哪些蛋白质结构域对蛋白质-DNA和 蛋白质-蛋白质接触的识别。具体而言，该项目旨在 确定XPC-HR 23 B，XPA， 和RPA与含有位点特异性UV光损伤的DNA底物， 苯并[a]芘二醇环氧化物（BPDE）DNA加合物，使用严格的生物化学 方法：识别和分析重要的蛋白质基序参与 损伤识别：表征损伤的修复中间体 识别紫外线诱导的光损伤和BPDE-DNA加合物;并确定 损伤的结构和化学修饰的机制， 识别和修复。

Individuals who suffer from the genetic disease xeroderma pigmentosum (XP) lack nucleotide excision repair (NER) of DNA, and thus have much higher carcinogenic probability than the average population after exposure to UV irradiation. NER is a major cellular biological defense system to remove DNA damage due to the formation of bulky lesions induced by UV irradiation and environmental genotoxic chemicals and carcinogens. Although, it has been generally accepted that DNA damage recognition plays a central role in NER, the molecular and thermodynamic details of DNA damage processing remain largely unclear, and have not been systematically studied using biochemically rigorous approaches. In addition, the roles of the damage recognition proteins XPA, RPA, and XPC-HR23B have been controversial. The long-term objective of this study is to understand the molecular and biochemical details of UV-induced or related DNA damage recognition and repair by human NER proteins, and the potential effects of these relationships on damage-induced mutagenesis and carcinogenesis. To gain a systematic and more precise view of DNA damage recognition and repair by human NER, the following questions will be addressed: What is the hierarchy of damage recognition and how is damage dynamically processed in a stepwise recognition mechanism? What structural and chemical alterations in the DNA helix are identified by repair proteins at specific recognition steps? What is the molecular architecture of recognition intermediates? And what protein domains are important for protein-DNA and protein-protein contacts in the recognition. Specifically, this project aims to determine the thermodynamics and kinetics of the interaction of XPC-HR23B, XPA, and RPA with DNA substrates containing site-specific UV photolesions and benzo[a]pyrene diol epoxide (BPDE) DNA adducts using rigorous biochemical approaches: identify and analyze the important protein motifs involved in damage recognition: characterize the repair intermediates for damage recognition of UV-induced photolesions and BPDE-DNA adducts; and determine the mechanism in which the structural and chemical modifications of damage are recognized and repaired.