Roles of Multiple-Binding Sites of Conjugating Enzyme E2 in SUMOylation

一个小的泛素相关修饰物(SUMO)对蛋白质进行翻译后修饰，调节许多重要的细胞通路。相扑甲基化需要激活酶(E1)和结合酶(E2)的顺序作用，通常还需要介导底物特异性的连接酶(E3)才能相扑接合。在这个过程中，相扑从E1到E2的转移机制还没有很好的阐明。在本研究中，为了揭示E1、E2和SUMO之间的相互作用网络的功能作用，我们对水稻E1的E2、SUMO和E2结合域(UFD)进行了结构分析，发现E2具有多个亲和力不同的SUMO结合部位和一个单一的UFD结合部位。

Post-translational modification of proteins by a small ubiquitin-related modifier (SUMO) regulates many important celluar pathways. SUMOylation requires the sequential action of E1 (activating enzyme), E2 (conjugating enzyme) and often needs E3 (ligases) that mediate substrate specificity for SUMO conjugation. In this process, the transfer mechanism of SUMO from E1 to E2 has not been well clarified. In this study, to reveal the functional roles of interaction network among E1, E2 and SUMO, we performed structural analyses on E2, SUMO, and E2-binding domain (UFD) of E1 from rice, and identified that E2 has multiple SUMO-binding sites with distinct affinities as well as a single UFD-binding site.