新型蛋白质翻译后修饰S-GlcNAc糖基化的修饰酶及读码蛋白研究

蛋白质的O-GlcNAc修饰是最重要的可逆糖基化修饰之一，并参与到广泛的生物学过程中。已知的蛋白质O-GlcNAc糖基化修饰仅由一对酶，OGT和OGA，来实现动态调控。近期的蛋白组学研究揭示了半胱氨酸的S-GlcNAc修饰作为新型翻译后修饰的存在。我们的前期研究表明，OGT可催化该S-糖基转移反应，意味着OGT是能够催化O-和S-GlcNAc两种糖基化修饰的双功能糖基转移酶。本项目拟围绕S-GlcNAc糖基化的修饰酶与读码蛋白开展研究：（1）表征OGT催化S-糖基转移反应的功能和酶学机理，探求其催化O-与S-GlcNAc两种糖基化反应机理的异同；（2）设计合成多肽分子探针用于发现和鉴定特异性识别S-GlcNAc修饰的读码蛋白，并表征其结合机制。该项目有望拓展对酶促糖基转移反应这一基础且重要的化学转化的理解，开发特异性标记此类翻译后修饰的方法，助力S-GlcNAc蛋白修饰的组学研究。

O-GlcNAc modification of proteins is one of the most important intracellular posttranslational modifications (PTMs), which is controlled by OGT and OGA for the dynamic installation and removal of GlcNAc from proteins, respectively. Recent proteomic studies revealed S-GlcNAc modification as a new type of PTMs. Our preliminary study showed that OGT exhibits ability to catalyze such transformation, indicating that OGT is a bifunctional glycosyl transferase for both O- and S-GlcNAc glycosylation. This project aims to investigate the modification enzyme and reader proteins for S-GlcNAc glycosylation, including 1) to elucidate the mechanism of O- and S-GlcNAc modification catalyzed by OGT; 2) to design and synthesize peptide probes bearing S-GlcNAc motifs to fish out reader proteins that specifically recognize S-GlcNAc modification. Through this project, we hope to provide important information regarding the enzymatic mechanism of OGT for both glycosylation reactions and reader proteins involved in the biological functions of S-GlcNAc modification.