Microscopic Aspects of DNA Translocation by hOGG1 DNA Glycosylase

约翰霍普金斯大学的James Stivers教授利用由化学系生命过程化学项目资助的这一奖项，试图阐明一种范式DNA修复蛋白（即人类8-氧鸟嘌呤DNA糖基酶）如何沿着DNA链易位以发现损伤的基本基础。目前的模型表明，DNA滑动，即蛋白质与DNA链保持恒定的接触，是损伤识别的主要模式。然而，这些模型是基于单分子成像方法的结果，不具有时间或空间分辨率来检测DNA上蛋白质的重要微观跟踪事件，如链跳。Stivers教授使用了一种动力学方法，可以量化DNA上蛋白质易位的滑动和跳跃事件。该研究旨在阐明非特异性静电相互作用如何通过对DNA主链进行化学修饰，特别是中性甲基膦酸盐取代，以及通过表达的蛋白质连接将阳离子肽尾附加到蛋白质上，从而促进链滑动。本研究的结果有望促进对非特异性蛋白质-核酸静电相互作用如何强调搜索动力学和机制的基本理解，并为解释DNA滑动的单分子测量结果提供有用的数据。生物分子之间的有效结合是生命的基本要求，它是由参与结合的伙伴的化学性质决定的。对于与基因组DNA相互作用的蛋白质，形成导致DNA修复、复制或转录的特定复合物利用了DNA的线性链结构。因此，蛋白质可以在距离特定靶点很远的地方与DNA结合，并利用DNA链作为寻找靶点的轨道。这项工作将研究DNA修复蛋白用来追踪DNA以找到受损位点的相互作用，如果不修复，受损位点将导致突变和疾病。该奖项开发的技术将为其他科学家提供研究方法，并有助于蛋白质- dna识别的一般知识。该计划还旨在鼓励年轻人接受生物物理学和相关科学方面的培训。本科和高中研究人员（包括来自STEM职业中代表性不足的群体的学生）将参加由Stivers教授指导的暑期研究实习。Stivers教授将继续参加和组织各种多学科会议、讲习班和夏季课程，通过这些会议，他和其他人的研究成果将被传播到科学界。

Using this award funded by the Chemical of Life Processes Program of the Division of Chemistry, Professor James Stivers from the Johns Hopkins University seeks to elucidate the fundamental basis for how a paradigm DNA repair protein, namely human 8-oxoguanine DNA glycosylase, translocates along a DNA chain to find damage. Present models suggest that DNA sliding, where the protein remains in constant contact with the DNA chain, is the primary mode for damage recognition. However, these models are based on the results of single-molecule imaging methods that do not have the temporal or spatial resolution to detect important microscopic tracking events of the protein on DNA such as chain hopping. Professor Stivers uses a kinetic approach that allows quantification of both sliding and hopping events involved in protein translocation on DNA. The research aims to elucidate how nonspecific electrostatic interactions promote chain sliding by using chemical modifications of the DNA backbone, specifically neutral methylphosphonate substitutions, and by appending cationic peptide tails to the protein through expressed protein ligation. The results of this research are expected to facilitate a fundamental understanding of how nonspecific protein-nucleic acid electrostatic interactions underline the kinetics and mechanism of the search, and to provide data useful for the interpretation of the results of single molecule measurements of DNA sliding. The efficient binding between biomolecules is a fundamental requirement of life that is governed by the chemical properties of the partners that participate in the binding. For proteins that interact with genomic DNA, the formation of specific complexes that result in DNA repair, replication or transcription takes advantage of the linear chain structure of DNA. Thus, proteins can bind to DNA a great distance from a specific target site and use the DNA chain as a track to find the target site. This work will examine the interactions that a DNA repair protein uses to track along DNA to find a damaged site, which would result in mutation and disease if not repaired. The techniques developed from this award will provide investigative methods to other scientists and contribute to general knowledge of protein-DNA recognition. This program is also designed to encourage young people to pursue training in biophysics and related sciences. Undergraduate and high school researchers (including students from groups underrepresented in STEM careers) will participate in summer research internships guided by Professor Stivers. Professor Stivers will continue to participate in- and organize- a variety of multidisciplinary conferences, workshops and summer courses through which his and others research results are disseminated to the scientific community.