OXIDATIVE DNA DAMAGE AND EXOCYCLIC DNA ADDUCTS

此应用程序侧重于DNA双链水平上的结构比对 与基本部位、外环加合物、8-氧-嘌呤损伤和 芳香胺加合物在化学和生物化学中起着关键作用 辐射致癌。这些解决方案的结构 损伤将由核磁共振和分子动力学相结合来定义 在已定义的序列上下文中进行细化。在我们的基础上的新方向 网站研究将集中在含有相反缺失的基本网站 难治性皮损和双链基本部位皮损 修理。这些结构研究将扩展到核糖核酸内酯。 基础部位既可作为孤立病变也可作为相关的双链病变 新癌抑素的作用。外环加合物的研究将是 延伸到强致癌物质乙烯基的乙烯基外环加合物 氯化物与脱氧鸟嘌呤、脱氧腺嘌呤和脱氧胞苷。我们会 探讨外环加合物上的同源对齐的共性 适应外环所需的结构扰动的程度 螺旋线内的环。结构研究将与 选择性识别这些外环的DNA糖基酶的研究 内收物取决于与病变部位相对的碱基。我们计划 脱氧鸟嘌呤氧化损伤的比较结构研究 和脱氧腺嘌呤在相同的序列背景下，试图理解 8-oxo-DG与8-oxo-DG相比致突变性增强的原因 DA，它是非致突变的。还将尝试描述以下特征 脱氧尿嘧啶在DNA低聚体上的咪唑开环Fapy加合物 水平。我们先前对碱基替换比对的结构研究 在C8-脱氧鸟嘌呤芳香胺加合物位置被扩展到 特定序列上下文中的单删除和双删除移帧 建立在体外复制研究基础上。我们的努力将尝试 确定(AAF)DG和(AF)DG在移框位置的构象 并确定与单个和 双重删除。这种比较分析也将扩展到 抗氧化剂致癌物质(ABP)DG和食物毒素(PhIP)DG加合物 评估芳香胺环系对 病变部位的结构对齐。总体目标是将两个 我们的核磁共振结构研究和相关的量热测量 在肯·布雷斯劳尔教授的实验室里研究了这四个DNA损伤家族 在弗朗西斯·约翰逊教授的实验室里准备的。这些研究将 提供必要的结构热力学框架 教授实验室中诱变实验的解释。 亚瑟·格罗尔曼和约翰·埃西格曼。

This application focuses on structural alignments at the DNA duplex level associated with abasic sites, exocyclic adducts, 8-oxo-purine lesions and aromatic amine adducts which play a critical role in chemical and radiation induced carcinogenesis. The solution structure of these lesions will be defined by a combination of NMR and molecular dynamics refinements in defined sequence contexts. New directions in our abasic site research will focus on abasic sites containing deletions opposite the lesion and bistrand abasic site lesions which are refractory to repair. These structural studies will be extended to ribonolactone abasic sites both as isolated lesions and as bistrand lesions relevant to neocarcinostatin action. The exocyclic adduct research will be extended to etheno exocyclic adducts of the potent carcinogen vinyl chloride with deoxyguanine, deoxyadenine and deoxycytidine. We shall probe the generality of syn alignments at the exocyclic adduct and the extent of structural perturbations necessary to accommodate the exocyclic ring within the helix. The structural research will be correlated with research on DNA glycosylases which selectively recognize these exocyclic adducts depending on the base opposite the lesion site. We plan a comparative structural investigation of oxidative damage at deoxyguanine and deoxyadenine in the same sequence context in an attempt to understand the origin of the enhanced mutagenicity of 8-oxo-Dg in contrast to 8-oxo- Da which is non-mutagenic. An attempt will be also made to characterize imidazole ring-opened FAPY adducts of deoxypurines at the DNA oligomer level. Our previous structural research on base substitution alignments at C8-deoxyguanine aromatic amine adduct sites are being extended to single and double deletion frame-shifts in specific sequence contexts established from in vitro replication studies. Our efforts will attempt to define the conformation of (AAF)Dg and (AF) Dg at the frame-shift site and identify the structural differences associated with a single and double deletions. Such a comparative analysis will also be extended to the anti-oxidant carcinogen (ABP)Dg and the food toxin (PhIP)Dg adducts to evaluate contributions from the aromatic amine ring system to structural alignments at the lesion site. The overall goal is to couple our NMR structural investigations with related calorimetric measurements in Prof. Ken Breslauer's laboratory on these four families of DNA lesions prepared in Prof. Francis Johnson's laboratory. These studies will provide the structural-thermodynamics framework necessary for interpretation of mutagenesis experiments in the laboratories of Profs. Arthur Grollman and John Essigmann.