Weber E R, Hanekamp T, Thorsness P E
Department of Molecular Biology, University of Wyoming, Laramie 82071-3944, USA.
Mol Biol Cell. 1996 Feb;7(2):307-17. doi: 10.1091/mbc.7.2.307.
Inactivation of YME1 in yeast causes several distinct phenotypes: an increased rate of DNA escape from mitochondria, temperature-sensitive growth on nonfermentable carbon sources, extremely slow growth when mitochondrial DNA is completely absent from the cell, and altered morphology of the mitochondrial compartment. The protein encoded by YME1, Yme1p, contains two highly conserved sequence elements, one implicated in the binding and hydrolysis of ATP, and the second characteristic of active site residues found in neutral, zinc-dependent proteases. Both the putative ATPase and zinc-dependent protease elements are necessary for the function of Yme1p as genes having mutations in critical residues of either of these motifs are unable to suppress any of the phenotypes exhibited by yme1 deletion strains. Yme1p co-fractionates with proteins associated with the mitochondrial inner membrane, is tightly associated with this membrane, and is oriented with the bulk of the protein facing the matrix. Unassembled subunit II of cytochrome oxidase is stabilized in yme1 yeast strains. The data support a model in which Yme1p is an ATP and zinc-dependent protease associated with the matrix side of the inner mitochondrial membrane. Subunit II of cytochrome oxidase, when not assembled into a higher order complex, is a likely substrate of Yme1p.
酵母中YME1的失活会导致几种不同的表型：线粒体中DNA逸出速率增加、在非发酵碳源上生长对温度敏感、当细胞中完全没有线粒体DNA时生长极其缓慢，以及线粒体区室形态改变。YME1编码的蛋白质Yme1p包含两个高度保守的序列元件，一个与ATP的结合和水解有关，另一个是中性锌依赖性蛋白酶中活性位点残基的特征。假定的ATP酶和锌依赖性蛋白酶元件对于Yme1p的功能都是必需的，因为在这些基序的关键残基中发生突变的基因无法抑制yme1缺失菌株所表现出的任何表型。Yme1p与线粒体内膜相关蛋白共分级分离，与该膜紧密结合，并且其大部分蛋白质面向基质。细胞色素氧化酶未组装的亚基II在yme1酵母菌株中稳定存在。这些数据支持了一个模型，其中Yme1p是一种与线粒体内膜基质侧相关的ATP和锌依赖性蛋白酶。细胞色素氧化酶的亚基II在未组装成更高阶复合物时，可能是Yme1p的底物。
