Clarkson G H, Poyton R O
Department of Molecular, Cellular, and Development Biology, University of Colorado, Boulder 80309-0347.
J Biol Chem. 1989 Jun 15;264(17):10114-8.
Subunit II of yeast cytochrome c oxidase is synthesized on mitochondrial ribosomes as a precursor containing a transient NH2-terminal presequence and is inserted into the mitochondrial inner membrane from the matrix side. Using an optimized in vitro mitochondrial translation system (McKee, E.E., and Poyton, R. O. (1984) J. Biol. Chem. 259, 9320-9331), we have examined the requirement for an electrochemical potential (delta mu H+) across the inner mitochondrial membrane during subunit II biogenesis. When mitochondrial gene products are synthesized under conditions that prevent formation of a normal delta mu H+, accumulation of unprocessed subunit II (pre-II) occurs. The majority of pre-II generated in this way is inserted into the lipid bilayer, as judged by resistance to extraction with 0.1 M Na2CO3. Therefore, it appears that a delta mu H+ is required for the normal biogenesis of subunit II, and that the delta mu H+ is required for a function other than the insertion of pre-II into the lipid bilayer of the inner membrane.
酵母细胞色素c氧化酶的亚基II在线粒体核糖体上作为一种含有短暂氨基末端前序列的前体进行合成,并从基质侧插入线粒体内膜。利用优化的体外线粒体翻译系统(麦基,E.E.,和波伊顿,R.O.(1984年)《生物化学杂志》259,9320 - 9331),我们研究了亚基II生物合成过程中线粒体内膜两侧电化学势(ΔμH⁺)的需求。当线粒体基因产物在阻止正常ΔμH⁺形成的条件下合成时,未加工的亚基II(前体 - II)会积累。通过对0.1 M Na₂CO₃提取的抗性判断,以这种方式产生的大多数前体 - II插入到脂质双层中。因此,似乎ΔμH⁺对于亚基II的正常生物合成是必需的,并且ΔμH⁺对于除了将前体 - II插入内膜脂质双层之外的其他功能也是必需的。