摘要
泛素及其相关蛋白是真核细胞中广泛存在的结构高度保守的一类小分子蛋白,参与蛋白翻译后修饰.尽管在少数原核种属含有Pupylation这样的翻译后修饰,在原核细胞中尚未发现通用的泛素样修饰系统.ThiS是原核细胞广泛存在的泛素样小蛋白分子,它作为硫转运蛋白参与辅助因子的合成.当与靶蛋白融合重组表达时,ThiS可降低靶蛋白在大肠杆菌中的稳定性.本研究旨在探讨ThiS是否可能在原核细胞中参与翻译后修饰.ThiS在大肠杆菌中重组表达时,它可与细胞蛋白游离巯基发生共价结合,但与真核细胞泛素修饰不同,ThiS是通过12位半胱氨酸的游离巯基与蛋白形成二硫键,而不是通过C端活化的硫代羧基的转化过程发生共价结合.在细胞内,氧化应激可诱导ThiS与蛋白的共价结合.结果提示,ThiS在大肠杆菌中与细胞蛋白的结合,可能与真核细胞泛素化修饰在功能上存在进化联系;原核细胞中这种ThiS的结合形式可能代表一种古老的原核泛素样修饰方式.
Ubiquitin-like polypeptides are highly conserved small proteins found in eukaryotes for proteinpost-translational modifications. Although pupylation exists in a few prokaryotic species, ubiquitin-likemodification system has not been identified in prokaryotes. Prokaryotic ubiquitin-like ThiS is a smallsulfur-carrier protein involved in cofactor synthesis. It reduces the stability of the recombinant fusionpeptides expressed in E. coli. We conducted experiments to explore the possible role of ThiS in proteinpost-translational modification in the host cells. Overexpressed ThiS in E. coli was identified to covalentlyconjugate to the free thiol groups of cellular proteins. Unlike eukaryotic ubiquitin modification, ThiSconjugates at the residue Cys 12 via disulfide bonding instead of at the C-terminal carboxyl thiol. ThiSconjugation can be induced in vivo under oxidative stress. Our data suggested protein conjugation withThiS might partially resemble to the ubiquitin modification in eukaryotes.
出处
《中国生物化学与分子生物学报》
CAS
CSCD
北大核心
2014年第7期685-690,共6页
Chinese Journal of Biochemistry and Molecular Biology
基金
Supported by National Science&Technology Major Project“New Drug Innovation and Production Program”of China(General platform construction,No:2012ZX09301002-001-002 and 2012ZX09301002-002-006)~~
关键词
原核生物
硫转运蛋白
翻译后修饰
二硫键
氧化应激
stressprokaryote
sulfur-carrier protein
post-translational modification
disulfide
oxidative
作者简介
共同第一作者
共同第一作者
联系人Tel：010-83172984；E-mail：wangnan@imm．ac．cn
