REPAIR OF OXIC AND ANOXIC DNA DAMAGES

修复氧化和缺氧 DNA 损伤

• 批准号: 2872711
• 负责人: YOKE W KOW
• 金额: $ 23.41万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-01 至 2001-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2872711
• 关键词: DNA damage; DNA footprinting; DNA repair; Escherichia coli; anomer; crosslink; enzyme activity; gel mobility shift assay; hypoxia; ionizing radiation; molecular site; mutant; phosphoester ligase; plasmids; protein purification; pyrimidines; radiation genetics; radiation sensitivity; thymine; tissue /cell culture

Ionizing radiation produces a wide spectrum of DNA damages to the base and sugar moieties of DNA. The spectrum of damages induced by ionizing radiation in aqueous solution is affected by the dissolved gases, such as oxygen. Damages such as dihydrothymine, a-anomers, cyclopurines and pyrimidines are only formed under anoxic conditions. While the biological processing of a number of the oxic DNA damages are well understood, the repair and removal of most of the anoxic lesions remains unclear. It is well known that cell survival increased under hypoxia irradiation. The long range goal of this research is to elucidate mechanism of processing of DNA damage induced by ionizing radiation in hypoxic cells E. coli cells deficient in different repair enzymes will be studied with respect to their sensitivities to killing by ionizing radiation under anoxic and oxic conditions. This study should aid in the process of identifying novel enzymes that might be involved in the biological processing of these anoxic lesions. Duplex DNA containing unique anoxic lesions such as dihydrothymine, alpha-dA, 8,5'-cyclopurines and model DNA-protein crosslinks will be constructed and used as substrates for screening of enzymatic activities that might recognize these lesions. Novel enzymatic activities detected will be purified and characterized. The biological processing of these lesions will also be studied by the survival of plasmid DNA containing these lesions in E. coli hosts of different repair proficiency. The in vitro and in vivo processing of another important class of lesion, locally multiply damage sites, will also be studied in a similar manner. It is hoped that through a combination of enzymological and genetic studies, the mechanism of increased survival in hypoxic cells can be elucidated. The long range goal of this project is to develop methods that can enhance the radiation killing of hypoxic tumor cells and thus the therapeutic efficacy of radiotherapy.

电离辐射会对底座产生广泛的DNA损伤， DNA的糖部分。电离引起的损害范围 水溶液中的辐射受溶解气体的影响，例如 氧。二氢噻吩，A-ANOMERS，环肽和诸如损害赔偿 嘧啶仅在缺氧条件下形成。而生物学 对许多毒性DNA损害的处理已被充分了解， 大多数缺氧病变的修复和去除尚不清楚。这是 众所周知，在缺氧辐射下，细胞存活增加。长 这项研究的范围目标是阐明DNA处理机制 低氧细胞大肠杆菌细胞中电离辐射引起的损伤 将研究不同的维修酶 通过在缺氧和毒性下电离辐射来杀死的敏感性 状况。这项研究应有助于确定新颖的过程 可能参与这些缺氧的生物加工的酶 病变。 双链DNA包含独特的缺氧病变，例如 二氢氨基氨酸，α-da，8,5'-循环和型号DNA-蛋白质 交联将构造并用作筛选的基材 可能识别这些病变的酶活性。新型酶促 检测到的活动将被纯化和表征。生物学 这些病变的加工​​也将通过质粒的存活来研究 在大肠杆菌中包含这些病变的DNA不同修复的宿主 熟练程度。另一个重要类的体外和体内处理 病变的局部倍增位点也将在类似的 方式。希望通过酶学和遗传的结合 研究，低氧细胞生存率增加的机制可以是 阐明。该项目的远距离目标是开发方法 可以增强低氧肿瘤细胞的辐射杀死，从而增加 放射疗法的治疗功效。