The SUMO isopeptidase Ulp2 prevents accumulation of SUMO chains in yeast
The SUMO isopeptidase Ulp2 prevents accumulation of SUMO chains in yeast
复制标题
DOI：
10.1074/jbc.m308357200
复制
发表时间：
2003-11-07
影响因子：
4.8
通讯作者：
Johnson, ES
中科院分区：
文献类型：
--
作者：
Bylebyl, GR;Belichenko, I;Johnson, ES
泛素相关蛋白SUMO通过共价连接到其他蛋白质中的赖氨酸残基来发挥功能。与泛素不同，泛素通常作为聚泛素链与其底物连接，在大多数底物中，每个修饰位点仅连接一个SUMO部分。然而，SUMO最近已被证明在体外和哺乳动物细胞中形成链，在非泛素样N-末端延伸中的赖氨酸作为主要的SUMO-SUMO分支位点。为了研究SUMO链的生理功能，我们产生了表达缺乏各种赖氨酸残基的突变SUMO的酿酒酵母菌株。否则，野生型菌株缺乏任何9个赖氨酸的SUMO是可行的，没有明显的生长缺陷或应力敏感性，并有SUMO共轭模式，没有显着不同的野生型。然而，缺乏SUMO特异性异肽酶Ulp 2的突变体积累了含有高分子量SUMO的物种，这些物种仅在SUMO的N末端赖氨酸存在时形成，这表明它们含有SUMO链。此外，SUMO分支位点突变体抑制了ulp 2Delta的几种表型，这与一些ulp 2Delta表型是由SUMO链积累引起的可能性一致。我们还发现，一个突变的SUMO的非泛素样N-末端结构域已被完全删除，仍然进行了所有的基本功能的SUMO。因此，SUMO的泛素样结构域足以用于接合和酵母活力所需的所有下游功能。我们的数据表明，SUMO可以在酵母体内形成链，但最终证明，链的形成是不需要的SUMO在S。啤酒。
The ubiquitin-related protein SUMO functions by becoming covalently attached to lysine residues in other proteins. Unlike ubiquitin, which is often linked to its substrates as a polyubiquitin chain, only one SUMO moiety is attached per modified site in most substrates. However, SUMO has recently been shown to form chains in vitro and in mammalian cells, with a lysine in the non-ubiquitin-like N-terminal extension serving as the major SUMO-SUMO branch site. To investigate the physiological function of SUMO chains, we generated Saccharomyces cerevisiae strains that expressed mutant SUMOs lacking various lysine residues. Otherwise wildtype strains lacking any of the nine lysines in SUMO were viable, had no obvious growth defects or stress sensitivities, and had SUMO conjugate patterns that did not differ dramatically from wild type. However, mutants lacking the SUMO-specific isopeptidase Ulp2 accumulated high molecular weight SUMO-containing species, which formed only when the N-terminal lysines of SUMO were present, suggesting that they contained SUMO chains. Furthermore SUMO branch-site mutants suppressed several of the phenotypes of ulp2Delta, consistent with the possibility that some ulp2Delta phenotypes are caused by accumulation of SUMO chains. We also found that a mutant SUMO whose non-ubiquitin- like N-terminal domain had been entirely deleted still carried out all the essential functions of SUMO. Thus, the ubiquitin-like domain of SUMO is sufficient for conjugation and all downstream functions required for yeast viability. Our data suggest that SUMO can form chains in vivo in yeast but demonstrate conclusively that chain formation is not required for the essential functions of SUMO in S. cerevisiae.