Nakai M, Endo T, Hase T, Matsubara H
Department of Chemistry, Faculty of Science, Nagoya University, Japan.
J Biol Chem. 1993 Nov 15;268(32):24262-9.
Replacement of the presequence of yeast cytochrome c1 by the amino-terminal 61 residues of MAS70, a yeast mitochondrial outer membrane protein, resulted in exclusive localization of the fusion protein (termed the 61-mC1 protein) to the outer membrane. When a cytochrome c1-deficient yeast strain was transformed with a plasmid encoding the fusion protein, the cells could not grow on nonfermentable carbon sources such as glycerol. We isolated a novel yeast gene MSP1 (mitochondrial sorting of proteins) whose overexpression causes mislocalization of the 61mC1 fusion protein to the inner membrane, probably via the intermembrane space, and thereby allows the host cells to grow on glycerol. The predicted MSP1 protein (MSP1) is a hydrophilic 40-kDa polypeptide containing a putative membrane-spanning domain near the amino terminus. Further sequence analyses revealed that MSP1 is a member of a novel family of putative ATPases which share a highly conserved domain of about 185 amino acid residues, including a consensus motif for a nucleotide binding site. MSP1 was found to be an intrinsic mitochondrial outer membrane protein of an apparent molecular mass of 40 kDa with a large domain facing to the cytosol. The MSP1 gene is not essential for the cell growth either on fermentable or nonfermentable carbon sources.
将酵母细胞色素c1的前序列替换为酵母线粒体外膜蛋白MAS70的氨基末端61个残基，导致融合蛋白（称为61-mC1蛋白）专一性定位于外膜。当用编码融合蛋白的质粒转化细胞色素c1缺陷型酵母菌株时，细胞无法在甘油等非发酵碳源上生长。我们分离出一个新的酵母基因MSP1（蛋白质的线粒体分选），其过表达导致61mC1融合蛋白可能通过膜间隙错误定位于内膜，从而使宿主细胞能够在甘油上生长。预测的MSP1蛋白（MSP1）是一种亲水性40 kDa多肽，在氨基末端附近含有一个推定的跨膜结构域。进一步的序列分析表明，MSP1是一个新的推定ATP酶家族的成员，它们共享一个约185个氨基酸残基的高度保守结构域，包括一个核苷酸结合位点的共有基序。发现MSP1是一种表观分子量为40 kDa的线粒体外膜内在蛋白，有一个大的结构域面向胞质溶胶。MSP1基因对于在可发酵或不可发酵碳源上的细胞生长都不是必需的。
