Sem1p is a novel subunit of the 26 S proteasome from Saccharomyces cerevisiae
Sem1p is a novel subunit of the 26 S proteasome from Saccharomyces cerevisiae
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DOI：
10.1074/jbc.m403165200
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发表时间：
2004-07-02
影响因子：
4.8
通讯作者：
Yokosawa, H
中科院分区：
文献类型：
--
作者：
Sone, T;Saeki, Y;Yokosawa, H
26个S蛋白酶体由20个S蛋白酶体和19个S调节颗粒(RP)组成，催化多泛素蛋白的降解。该蛋白由盖子和碱基组成，调节着20 S蛋白酶体的催化活性。在本研究中，我们对酿酒酵母标记菌株的盖子和碱基亚复合体进行了亲和纯化，发现盖子中含有一个小分子质量的蛋白质Sem1。Sem1蛋白与从缺失了sem1的突变体中分离的26个S蛋白酶体结合，而不与野生型的26个S蛋白酶体结合。缺少Sem1的盖子在高盐浓度下不稳定。以血凝素表位标记的Sem1为诱饵，用免疫沉淀法将19株S RP与Sem1一起免疫沉淀。体内或体外多泛素化蛋白的降解在缺乏Sem1的26 S蛋白酶体中受到损害。此外，还检测到SEM1和RPN10之间的遗传互作。人类Sem1同源物hDSS1是Sem1的功能同源物，能够与人26 S蛋白酶体相互作用。结果表明，Sem1可能是26 S蛋白酶体的一个新亚基，在泛素依赖的蛋白水解酶中发挥作用。
The 26 S proteasome, which catalyzes degradation of polyubiquitinated proteins, is composed of the 20 S proteasome and the 19 S regulatory particle ( RP). The RP is composed of the lid and base subcomplexes and regulates the catalytic activity of the 20 S proteasome. In this study, we carried out affinity purification of the lid and base subcomplexes from the tagged strains of Saccharomyces cerevisiae, and we found that the lid contains a small molecular mass protein, Sem1. The Sem1 protein binds with the 26 S proteasome isolated from a mutant with deletion of SEM1 but not with the 26 S proteasome from the wild type. The lid lacking Sem1 is unstable at a high salt concentration. The 19 S RP was immunoprecipitated together with Sem1 by immunoprecipitation using hemagglutinin epitope-tagged Sem1 as bait. Degradation of polyubiquitinated proteins in vivo or in vitro is impaired in the Sem1-deficient 26 S proteasome. In addition, genetic interaction between SEM1 and RPN10 was detected. The human Sem1 homologue hDSS1 was found to be a functional homologue of Sem1 and capable of interacting with the human 26 S proteasome. The results suggest that Sem1, possibly hDSS1, is a novel subunit of the 26 S proteasome and plays a role in ubiquitin-dependent proteolysis.