Identification of the gal4 suppressor Sug1 as a subunit of the yeast 26S proteasome
Identification of the gal4 suppressor Sug1 as a subunit of the yeast 26S proteasome
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DOI：
10.1038/379655a0
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发表时间：
1996-02-15
期刊：
影响因子：
64.8
通讯作者：
Finley, D
中科院分区：
文献类型：
--
作者：
Rubin, DM;Coux, O;Finley, D
酿酒酵母的SUG1基因编码一种假定的三磷酸腺苷酶。SUG1的突变被分离出来(1)，作为GAL4转录激活域突变的抑制因子。Sug1最近被认为是RNA聚合酶II全酶的一个亚基，并介导转录激活剂与全酶的关联(2)。我们在这里表明，Sug1不是全酶的亚基，至少在其纯化形式中不是，而是26S蛋白酶体的亚基（3,4），26S蛋白酶体是一种相对分子质量为2,000K的大型复合物，可催化泛素蛋白偶联物的atp依赖性降解。Sug1在常规和镍螯合亲和层析中与蛋白酶体共同纯化。我们的观察解释了sug1突变体中泛素依赖性蛋白水解的减少(5)，并表明sug1突变对转录的影响是蛋白质水解缺陷的间接结果。
THE SUG1 gene of Saccharomyces cerevisiae encodes a putative ATPase. Mutations in SUG1 were isolated(1) as suppressors of a mutation in the transcriptional activation domain of GAL4. Sug1 was recently proposed to be a subunit of the RNA polymerase II holoenzyme and to mediate the association of transcriptional activators with holoenzyme(2). We show here that Sug1 is not a subunit of the holoenzyme, at least in its purified form, but of the 26S proteasome(3,4), a large complex of relative molecular-mass 2,000K that catalyses the ATP-dependent degradation of ubiquitin-protein conjugates. Sug1 co-purifies with the proteasome in both conventional and nickel-chelate affinity chromatography. Our observations account for the reduced ubiquitin-dependent proteolysis in sug1 mutants(5) and suggest that the effects of sug1 mutations on transcription are indirect results of defective proteolysis.