The Cox3p assembly module of yeast cytochrome oxidase.
The Cox3p assembly module of yeast cytochrome oxidase.
复制标题
酵母细胞色素氧化酶的 Cox3p 组装模块。
DOI：
10.1091/mbc.e13-10-0575
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发表时间：
2014
影响因子：
3.3
通讯作者：
Tzagoloff,Alexander
中科院分区：
文献类型：
--
作者：
Su,Chen-Hsien;McStay,GavinP;Tzagoloff,Alexander
酵母细胞色素氧化酶（COX）先前被推断为由三个模块组装而成，每个模块包含三个线粒体编码亚基中的一个，以及组成该呼吸复合物的八个核基因产物的不同子集。脉冲标记线粒体的下拉试验使我们能够表征Cox3p亚组件的行为作为COX前体，包含Cox4p， Cox7p和Cox13p。令人惊讶的是，Cox4p是另外两个复合物的组成部分，其中一个先前被认为是Cox1p生物发生的中间体。这表明，在全酶中与Cox1p和Cox3p接触的Cox4p可以通过两种途径被纳入COX。除了COX的亚基，一些Cox3p中间体含有Rcf1p，这是一种与稳定COX与bc1（泛醇-细胞色素c还原酶）复合物相互作用的超复合体相关的蛋白质。最后，我们的研究结果表明，虽然Cox1p模块的组装并不取决于Cox3p的存在，但反之亦然，因为在Cox1p翻译受阻的突变体中没有检测到Cox3p亚组装。这些研究支持了我们的建议，即Cox3p和Cox1p是独立的组装模块，具有独特的辅助因子和亚基组成，来自核基因组。
Yeast cytochrome oxidase (COX) was previously inferred to assemble from three modules, each containing one of the three mitochondrially encoded subunits and a different subset of the eight nuclear gene products that make up this respiratory complex. Pull-down assays of pulse-labeled mitochondria enabled us to characterize Cox3p subassemblies that behave as COX precursors and contain Cox4p, Cox7p, and Cox13p. Surprisingly, Cox4p is a constituent of two other complexes, one of which was previously proposed to be an intermediate of Cox1p biogenesis. This suggests that Cox4p, which contacts Cox1p and Cox3p in the holoenzyme, can be incorporated into COX by two alternative pathways. In addition to subunits of COX, some Cox3p intermediates contain Rcf1p, a protein associated with the supercomplex that stabilizes the interaction of COX with the bc1 (ubiquinol-cytochrome c reductase) complex. Finally, our results indicate that although assembly of the Cox1p module is not contingent on the presence of Cox3p, the converse is not true, as none of the Cox3p subassemblies were detected in a mutant blocked in translation of Cox1p. These studies support our proposal that Cox3p and Cox1p are separate assembly modules with unique compositions of ancillary factors and subunits derived from the nuclear genome.