Intrinsic Reactivity of DNA Secondary Structure

DNA 二级结构的固有反应性

• 批准号: 9106957
• 负责人: Steven Rokita
• 金额: $ 22.95万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-08-01 至 1995-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9106957&HistoricalAwards=false
• 关键词: Intrinsic; Reactivity; DNA; Secondary; Structure

An accurate description of NA secondary structure must now include many conformations beyond those represented by a random coil or Watson-Crick double helix. Structural variants such as cruciform, hairpin, and hinged DNA along with the more transiently formed bulged or slipped sequences are often cited as the possible origin of mutational hotspots. Such aberrant conformations may adversely affect both the fidelity of DNA repair and the rate of nucleotide modification. This study has been designed to examine the molecular basis of this latter process by systematically evaluating the effect of duplex structure on the reactivity of DNA in a well defined model system. Photochemical modification of synthetic oligonucleotides serves as the primary method of derivatization and specifically, pyrimidine dimerization will be used to indicate the requirements of base mobility and orientation for DNA hyperreactivity. Kinetic and product analysis will determine the reaction efficiencies in helical and hairpin conformations containing mispaired or unpaired nucleotides. Concurrent chemical and enzymatic studies will generate a traditional and necessary context for interpreting the photochemical results. 1) Selective oxidation of DNA by KMnO4 will indicate the general accessibility of the thymine bases and 2) strand scission catalyzed by S-1 nuclease will demonstrate the related accessibilty of the sugar phosphate backbone.

对NA二级结构的准确描述现在必须包括许多构象，而不是由随机卷曲或沃森-克里克双螺旋表示的构象。结构变异，如十字形、发夹和铰链DNA，以及更瞬时形成的凸起或滑动的序列，经常被认为是突变热点的可能来源。这种异常构象可能会对DNA修复的保真度和核苷酸修饰的速度产生不利影响。这项研究旨在通过在一个定义明确的模型系统中系统地评估双重结构对DNA反应活性的影响来检查后一种过程的分子基础。人工合成的寡核苷酸的光化学修饰是衍生化的主要方法，具体地说，嘧啶二聚作用将被用来指示DNA高反应性对碱基迁移率和取向的要求。动力学和产物分析将确定含有错配或未配对核苷酸的螺旋和发夹构象的反应效率。同时进行的化学和酶研究将产生解释光化学结果的传统和必要的背景。1)KMnO4选择性氧化脱氧核糖核酸表明胸腺嘧啶碱基的一般可及性；2)S-1核酸酶催化的断链表明磷酸糖骨架的相关可达性。