TET蛋白差异性催化5mC/5hmC/5fC的分子机制研究

项目名称： TET蛋白差异性催化5mC/5hmC/5fC的分子机制研究

项目编号： No.31470725

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 生物科学

项目作者： 李泽

作者单位： 复旦大学

项目金额： 85万元

中文摘要： 哺乳动物DNA甲基化发生在胞嘧啶第五位碳原子上（5mC），是重要的表观遗传学修饰，TET双加氧酶连续氧化DNA上的5mC成为5hmC、5fC和5caC,最终通过碱基切除修饰机制替换成胞嘧啶。TET蛋白在干细胞发育过程中发挥至关重要的作用，其失调导致多种白血病发生。申请人解析了TET2-DNA复合物的结构，揭示了TET蛋白识别DNA底物的分子机制（Cell，2013，共同第一作者）。后续研究发现TET对5mC和5hmC、5fC构成的DNA的酶活性有明显差异，该现象对研究TET蛋白连续催化5mC氧化有重要意义。 申请人拟解析TET蛋白与（5hmC、5fC）DNA复合物的结构，综合利用计算生物学、生物化学等技术，阐明TET对不同底物酶活性差异的分子机制，项目的完成将完善我们对DNA甲基化动态调控机制的理解，加深我们对TET蛋白生物学功能的认识。

中文关键词： 表观遗传学；TET双加氧酶；5-羟甲基胞嘧啶；蛋白质结构；分子机制

英文摘要： Mammalian DNA methylation occurs on the C-5 position of cytosine,which is an important epigenetic modification.TET dioxygenases sequentially oxidize the 5mC into 5hmC and 5fC untill 5caC.The 5caC is finally replaced into cytosine through BER pathway. 5hmC is not only involved in the 5mC oxidation pathway,like 5fC and 5caC,but also an important epigenetic biomarker.TET proteins play significant roles in stem-cell development,whose dysregulation lead to human leukamogenesis. The applicant successfully solved the complex struture of TET2 with 5mC-modified DNA,which reveals the molecular mechanisms of DNA substrate recognition by TET2 (Cell,2013,co-first author).In our following stduies,we found that TET dioxygenases oxidized 5mC-modified DNA substrate more efficiently than 5hmC and 5fC-modified substrates.This phenomenon indicates the biological significance of 5mC sequential oxidization catalyzed by TETs. Based on above results, we intend to solve the complex structure of TET with different modified(5hmC/5fC)DNA.Combinied with computational biology,biochemistry and other techniques,we'll elucidate the molecular mechanisms of TET to differentially catalyze the 5mC/5hmC/5fC modified DNA substrate.The accomplishment of this project will perfect the understanding about the dynamic regulatory mechanisms of DNA methylation,and deepen the knowledge of TET proteins' biological functions for us.

英文关键词： Epigenetics;TET dioxygenases;5-hydroxymethylcytosine;Protein structure;Molecular mechanisms