DNA Charge Transport Chemistry and Biology

描述(由申请人提供)：本申请的长期目标是了解DNA介导的电荷传输(CT)化学和生物学，以及与DNA氧化损伤和修复有关的含义。我们实验室的研究表明，DNA CT可以以一种依赖于序列和结构的方式，在很长的分子距离内进行损伤，并且可以受到DNA结合蛋白的调节。这种反应对堆积非常敏感。现在建议描述DNA CT的生物学后果和机会。将使用插层光氧化剂来探索对细胞核内DNA的氧化损伤。DNA损伤将在染色体的端粒区域和与外显子接壤的CpG岛内进行探测，以测试这些区域是否提供了DNA CT漏斗损伤的汇。我们将对转录活性区域和非活性区域进行比较。CT损伤的距离范围将通过三重靶向在体内确定。DNA结合蛋白是否有利地利用DNA CT也将被检查。碱基切除修复酶家族，特别是MutY和Endo III，将被探索其与DNA结合的氧化还原化学。我们将利用瞬时吸收、电子顺磁共振、电化学、DNA修饰电极和生化方法来表征野生型和突变型蛋白质/DNA CT。将开发用于探测DNA介导的CT的自旋陷阱，涉及DNA结合蛋白。此外，还将检测转录激活剂SoxR，以测试DNA介导的CT是否被用于远程信号和激活。在DNA介导的反应中，将使用电化学和瞬时吸收光谱检测DNA结合的转录因子的远程氧化，并将从生化角度探讨SoxR的远程激活。同时，瞬时吸收、荧光和生化方法将被用于定义明确的寡核苷酸组合，以探索与生物背景相关的DNA CT的重要特征。修饰后的碱基和鸟嘌呤将成为氧化的目标。我们将检查和比较电子和空穴的输运。除鸟嘌呤损伤外，还将招募其他用于还原和氧化CT的化学陷阱，包括胸腺嘧啶二聚体修复。

DESCRIPTION (provided by applicant): The long term objective of this proposed application is an understanding of DNA-mediated charge transport (CT) chemistry and biology and implications with respect to oxidative DNA damage and repair. Studies in our laboratory have shown that DNA CT can proceed over long molecular distances to effect damage, in a sequence- and structure-dependent fashion, and can be modulated by DNA-binding proteins. The reaction is exquisitely sensitive to stacking. It is proposed now to delineate the biological consequences and opportunities for DNA CT. Oxidative damage to DNA within the cell nucleus will be explored using intercalating photooxidants. DNA damage will be probed in telomeric regions of the chromosome and within CpG islands bordering exons to test whether these regions provide sinks to which damage is funneled by DNA CT. Transcriptionally active versus inactive regions will be compared. The distance range for CT damage will be established in vivo by triplex targeting. Whether DNA-binding proteins utilize DNA CT advantageously will also be examined. The family of base excision repair enzymes, notably MutY and Endo III, will be probed as to their DNA-bound redox chemistry. Transient absorption, EPR, electrochemistry, on DNA-modified electrodes and biochemical methods will be utilized to characterize protein/DNA CT using wild type and mutant proteins. Spin traps to probe DNA-mediated CT involving the DNA-bound protein will be developed. Also the transcriptional activator, SoxR will be examined to test whether DNA-mediated CT is exploited for long range signaling and activation. Oxidation of the DNA-bound transcription factor at long range in a DNA-mediated reaction will be examined using electrochemistry and transient absorption spectroscopy and the long range activation of SoxR will be probed biochemically. In parallel, transient absorption, fluorescence and biochemical methods will be utilized in well-defined oligonucleotide assemblies to probe the important characteristics of DNA CT relevant to the biological context. Modified bases and guanines will serve as targets of oxidation. Electron versus hole transport will be examined and compared. Other chemical traps for reductive and oxidative CT besides guanine damage will be enlisted including thymine dimer repair.