Doan Jeffrey W, Schmidt Timothy R, Wildman Derek E, Goodman Morris, Weiss Mark L, Grossman Lawrence I
Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, 540 E. Canfield Avenue, Detroit, MI 48201, USA.
J Bioenerg Biomembr. 2005 Feb;37(1):35-41. doi: 10.1007/s10863-005-4121-2.
Cytochrome c (CYC) and 9 of the 13 subunits of cytochrome c oxidase (complex IV; COX) were previously shown to have accelerated rates of nonsynonymous substitution in anthropoid primates. Cytochrome b, the mtDNA encoded subunit of ubiquinol-cytochrome c reductase (complex III), also showed an accelerated nonsynonymous substitution rate in anthropoid primates but rate information about the nuclear encoded subunits of complex III has been lacking. We now report that phylogenetic and relative rates analysis of a nuclear encoded catalytically active subunit of complex III, the iron-sulfur protein (ISP), shows an accelerated rate of amino acid replacement similar to cytochrome b. Because both ISP and subunit 9, whose function is not directly related to electron transport, are produced by cleavage into two subunits of the initial translation product of a single gene, it is probable that these two subunits of complex III have essentially identical underlying rates of mutation. Nevertheless, we find that the catalytically active ISP has an accelerated rate of amino acid replacement in anthropoid primates whereas the catalytically inactive subunit 9 does not.
细胞色素c（CYC）以及细胞色素c氧化酶（复合体IV；COX）13个亚基中的9个亚基，先前已被证明在类人猿灵长类动物中具有加速的非同义替换率。细胞色素b是泛醌-细胞色素c还原酶（复合体III）的线粒体DNA编码亚基，在类人猿灵长类动物中也显示出加速的非同义替换率，但一直缺乏关于复合体III核编码亚基的速率信息。我们现在报告，对复合体III的一个核编码催化活性亚基铁硫蛋白（ISP）的系统发育和相对速率分析显示，其氨基酸替换率加速，类似于细胞色素b。由于ISP和功能与电子传递无直接关系的亚基9都是由单个基因初始翻译产物切割成两个亚基产生的，因此复合体III的这两个亚基可能具有基本相同的潜在突变率。然而，我们发现，在类人猿灵长类动物中，具有催化活性的ISP氨基酸替换率加速，而无催化活性的亚基9则没有。
