STRUCTURE AND MECHANISM OF DNA INTERSTRAND CROSS-LINKING

许多抗肿瘤剂和有毒物质，包括重要的 环境污染物，通过化学物质发挥其毒性作用， 与DNA的反应在许多情况下，DNA的反应区域 与这些物质和所得产品的结构， 未知了解这些细节对于理解 这些物质的毒性。这项研究将审查 化学和生物化学的重要性问题， 抗肿瘤剂、毒素和毒物与核酸的相互作用 acids.具体目标包括： (1)我们将评估交联的序列特异性， DNA链间交联DNA溶液结构 在上一个资助期内合成的交联剂， 被设计为识别和交联多达6个核苷酸的序列， 长的 (2)我们将量化序列特异性、产率和结构 的dG-到-dG链内交联引起的氮芥， 双链DNA，探测意外的链间交叉的起源， 通过研究氮芥的连接序列特异性， 延伸亲电体之间距离的结构类似物， 调查链间交叉的效率和序列特异性， DNA与其他氮素酶的连接，并评估其影响 氮芥DNA-DNA链间交联的亲和力 识别弯曲DNA的蛋白质的研究， 埃西格曼 (3)我们将定义dG到dG顺铂的共价结构 在5 '-d（Gc）处诱导DNA-DNA链间交联，并确定 含有该交联的100-mer双链体在定义的亲和力 HMG家族蛋白质的位点 埃西格曼 (4)我们将建立DNA-DNA链间交联序列 亚硝基脲的特异性和共价结构， 氯乙醛和铬（VI）诱导的链间交联。 (5)我们将确定RNA-DNA杂交双链体是否可以交叉， 由七种双功能亲电体中的任何一种连接。这些结果可能 提供必要的背景资料， 设计靶向与RNA-DNA双链体共价反应的试剂。

Many antitumor agents and toxic substances, including important environmental pollutants, exert their toxic effects by chemical reaction with DNA. In numerous cases, the regions of DNA which react with these substances and the structures of the resulting products are unknown. Understanding these details is critical to understanding the toxic effects of these substances. The proposed research will examine issues of chemical and biochemical significance arising from the interaction of antitumor agents, toxins, and toxicants with nucleic acids. The specific aims include: (1) We will evaluate the sequence specificity of cross-linking and solution structure of cross-linked DNAs derived from DNA interstrand cross-linking agents synthesized during the previous grant period which were designed to recognize and cross-link sequences up to 6 nucleotides in length. (2) We will quantify the sequence specificity, yield, and structures of the dG-to-dG intrastrand cross-links caused by mechlorethamine in duplex DNA, probe the origin of the unexpected interstrand cross- linking sequence specificity of mechlorethamine by studying a structural analog which extends the distance between the electrophiles, survey the efficiency and sequence specificity for interstrand cross- linking of DNA with other nitrogen mustards, and evaluate the impact of the mechlorethamine DNA-DNA interstrand cross-link on the affinity of proteins which recognize bent DNA in collaboration with Professor Essigmann. (3) We will define the covalent structure of the dG-to-dG cisplatin induced DNA-DNA interstrand cross-link at 5'-d(Gc) and determine the affinity of a 100-mer duplex containing this cross-link at a defined site for an HMG-family protein in collaboration with Professor Essigmann. (4) We will establish the DNA-DNA interstrand cross-linking sequence specificity and covalent structure of the nitrosourea-, chloroacetaldehyde-, and chromium(Vl)-induced interstrand cross-links. (5) We will determine whether RNA-DNA hybrid duplexes can be cross- linked by any of seven bifunctional electrophiles. These results could contribute background information necessary for the eventual rational design of agents targeted to react covalently with the RNA-DNA duplex.