Arnold I, Pfeiffer K, Neupert W, Stuart R A, Schägger H
Institut für Physiologische Chemie der Universität München, 80336 München, Germany.
J Biol Chem. 1999 Jan 1;274(1):36-40. doi: 10.1074/jbc.274.1.36.
The subunit composition of the mitochondrial ATP synthase from Saccharomyces cerevisiae was analyzed using blue native gel electrophoresis and high resolution SDS-polyacrylamide gel electrophoresis. We report here the identification of a novel subunit of molecular mass of 6,687 Da, termed subunit j (Su j). An open reading frame of 127 base pairs (ATP18), which encodes for Su j, was identified on chromosome XIII. Su j does not display sequence similarity to ATP synthase subunits from other organisms. Data base searches, however, identified a potential homolog from Schizosaccharomyces pombe with 51% identity to Su j of S. cerevisiae. Su j, a small protein of 59 amino acid residues, has the characteristics of an integral inner membrane protein with a single transmembrane segment. Deletion of the ATP18 gene encoding Su j led to a strain (Deltasu j) completely deficient in oligomycin-sensitive ATPase activity and unable to grow on nonfermentable carbon sources. The presence of Su j is required for the stable expression of subunits 6 and f of the F0 membrane sector. In the absence of Su j, spontaneously arising rho- cells were observed that lacked also ubiquinol-cytochrome c reductase and cytochrome c oxidase activities. We conclude that Su j is a novel and essential subunit of yeast ATP synthase.
利用蓝色天然凝胶电泳和高分辨率SDS-聚丙烯酰胺凝胶电泳分析了酿酒酵母线粒体ATP合酶的亚基组成。我们在此报告鉴定出一种分子量为6687 Da的新型亚基，称为亚基j（Su j）。在第十三条染色体上鉴定出一个编码Su j的127个碱基对的开放阅读框（ATP18）。Su j与其他生物的ATP合酶亚基没有序列相似性。然而，数据库搜索发现粟酒裂殖酵母中有一个潜在的同源物，与酿酒酵母的Su j有51%的同一性。Su j是一种由59个氨基酸残基组成的小蛋白，具有一个单一跨膜片段的整合内膜蛋白的特征。编码Su j的ATP18基因的缺失导致一个菌株（Deltasu j）完全缺乏对寡霉素敏感的ATP酶活性，并且不能在非发酵碳源上生长。Su j的存在是F0膜区亚基6和f稳定表达所必需的。在没有Su j的情况下，观察到自发产生的rho-细胞，它们也缺乏泛醇-细胞色素c还原酶和细胞色素c氧化酶活性。我们得出结论，Su j是酵母ATP合酶的一个新的必需亚基。
