新型DNA糖基化酶AlkC识别损伤位点甲基化碱基结构与动力学基础研究

项目名称： 新型DNA糖基化酶AlkC识别损伤位点甲基化碱基结构与动力学基础研究

项目编号： No.21472229

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 环境科学、安全科学

项目作者： 曹春阳

作者单位： 中国科学院上海有机化学研究所

项目金额： 90万元

中文摘要： DNA碱基损伤会导致DNA复制错误，改变组织细胞基因组稳定性，从而致肿瘤发生。在生物体系中，DNA碱基甲基化损伤剪切修复酶能够特异性识别DNA碱基甲基化损伤位点，使损伤位点碱基糖苷键水解断裂以被其他酶进一步修复。AlkC与AlkD属于同一超家族，是一类结构与功能新颖的DNA甲基化损伤修复糖基化酶。但彼此同源性很低，功能差异较大。在识别损伤位点机制上AlkC可能介于糖基化酶AlkD和TAG之间。本项目旨在利用X-单晶衍射技术开展AlkC识别DNA中损伤位点甲基化碱基的结构生物学基础研究，同时利用核磁共振技术开展在AlkC作用下DNA碱基对的动力学特征研究，以期从结构与动力学两方面阐述AlkC识别DNA中损伤位点甲基化碱基机制。

中文关键词： DNA糖基化酶；AlkC；结构；动力学；损伤位点

英文摘要： DNA damage can result in the errors of DNA replication, further leading to genome unstable, which is related to cancer generation. In biological systems, DNA glycosylases can specifically recognize DNA damage sites, and initiate base excision repair of N3- and N7- methylpurines from genome by catalysing hydrolysis of N-glycosidic bond, generate abasic sites in DNA that can ultimately lead to single- and double-strand breaks. AlkC and AlKD belong to a new superfamily of DNA glycosylases in three dimensional structures and functions. However, they're just distant homologs due to very low identities, and they work differently from each other in identification of DNA damage sites. Recent research indicates that AlkC has substrate specificity between TAG and AlKD. In this project, we will focus on two aspects: 1) the structural mechanism about how AlkC recognizes methylated damaged site by using X-ray crystallization techniques, and 2) the DNA dynamical basis about how AlkC catalyzes hydrolysis of N-glycosic bond in damage sites by using NMR methods, thus we can understand the structural and dynamical basis for AlkC to specifically recognize the damged site methylated base in dsDNA.

英文关键词： DNA glycosylase;AlkC;structure;dynamic;damaged site