Tzagoloff A, Capitanio N, Nobrega M P, Gatti D
Department of Biological Sciences, Columbia University, New York, NY 10027.
EMBO J. 1990 Sep;9(9):2759-64. doi: 10.1002/j.1460-2075.1990.tb07463.x.
The synthesis of cytochrome oxidase in Saccharomyces cerevisiae was recently shown to require a protein encoded by the nuclear gene COX10. This protein was found to be homologous to the putative protein product of the open reading frame ORF1 reported in one of the cytochrome oxidase operons of Paracoccus denitrificans. In the present study we demonstrate the existence in yeast of a second nuclear gene, COX11, whose encoded protein is homologous to another open reading frame (ORF3) present in the same operon of P. denitrificans. Mutations in COX11 elicit a deficiency in cytochrome oxidase. In this and in other respects cox11 and cox10 mutants have very similar phenotypes. An antibody has been obtained against the yeast COX11 protein. The antibody recognizes a 28 kd protein in yeast mitochondria, consistent with the size of the protein predicted from the sequence of COX11. The COX11 protein is tightly associated with the mitochondrial membrane but is not a component of purified cytochrome oxidase. An analysis of cytochrome oxidase subunits in wild type and in a cox11 mutant suggests that the COX11 protein is not required either for synthesis or transport of the subunit polypeptides into mitochondria. It seems more probable that COX11 protein exerts its effect at some terminal stage of enzyme synthesis, perhaps in directing assembly of the subunits.
最近发现，酿酒酵母中细胞色素氧化酶的合成需要一个由核基因COX10编码的蛋白质。该蛋白质被发现与反硝化副球菌细胞色素氧化酶操纵子之一中报道的开放阅读框ORF1的推定蛋白质产物同源。在本研究中，我们证明了酵母中存在第二个核基因COX11，其编码的蛋白质与反硝化副球菌同一操纵子中存在的另一个开放阅读框（ORF3）同源。COX11中的突变导致细胞色素氧化酶缺乏。在这方面以及其他方面，cox11和cox10突变体具有非常相似的表型。已经获得了一种针对酵母COX11蛋白的抗体。该抗体识别酵母线粒体中的一种28 kd蛋白质，这与从COX11序列预测的蛋白质大小一致。COX11蛋白与线粒体膜紧密结合，但不是纯化的细胞色素氧化酶的组成部分。对野生型和cox11突变体中细胞色素氧化酶亚基的分析表明，COX11蛋白对于亚基多肽的合成或转运到线粒体中都不是必需的。COX11蛋白似乎更有可能在酶合成的某个终末阶段发挥作用，也许是在指导亚基的组装。
