Interactions among COX1, COX2, and COX3 mRNA-specific translational activator proteins on the inner surface of the mitochondrial inner membrane of Saccharomyces cerevisiae
Interactions among COX1, COX2, and COX3 mRNA-specific translational activator proteins on the inner surface of the mitochondrial inner membrane of Saccharomyces cerevisiae
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DOI：
10.1091/mbc.e02-08-0490
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发表时间：
2003-01-01
影响因子：
3.3
通讯作者：
Fox, TD
中科院分区：
文献类型：
--
作者：
Naithani, S;Saracco, SA;Fox, TD
细胞色素c氧化酶复合物的核心由其三个最大的亚基Cox1p、Cox2p和Cox3p组成，它们在酿酒酵母的线粒体DNA中编码并从内部插入内膜。 COX1、COX2 和 COX3 mRNA 的线粒体翻译分别由核编码蛋白 Pet309p、Pet111p 以及 Pet54p、Pet122p 和 Pet494p 的协同作用特异性激活 mRNA。因为翻译激活剂识别这些 mRNA 5'-非翻译前导序列中的位点，并且因为非翻译 mRNA 序列包含靶向其蛋白质产物的信息，所以激活剂可能在定位翻译中发挥作用。在此，我们报告了位于内膜基质侧的 mRNA 特异性翻译激活蛋白之间的物理关联。通过共免疫沉淀和双杂交实验检测到的这些相互作用表明，翻译激活蛋白可以在内膜表面组织，使得 Cox1p、Cox2p 和 Cox3p 的合成将共定位，从而促进细胞色素 c 氧化酶复合物核心的组装。此外，我们发现 Nam1p/Mtf2p 和翻译激活剂之间的相互作用，表明线粒体 mRNA 有组织地传递到翻译系统。
The core of the cytochrome c oxidase complex is composed of its three largest subunits, Cox1p, Cox2p, and Cox3p, which are encoded in mitochondrial DNA of Saccharomyces cerevisiae and inserted into the inner membrane from the inside. Mitochondrial translation of the COX1, COX2, and COX3 mRNAs is activated mRNA specifically by the nuclearly coded proteins Pet309p, Pet111p, and the concerted action of Pet54p, Pet122p, and Pet494p, respectively. Because the translational activators recognize sites in the 5'-untranslated leaders of these mRNAs and because untranslated mRNA sequences contain information for targeting their protein products, the activators are likely to play a role in localizing translation. Herein, we report physical associations among the mRNA-specific translational activator proteins, located on the matrix side of the inner membrane. These interactions, detected by coimmune precipitation and by two-hybrid experiments, suggest that the translational activator proteins could be organized on the surface of the inner membrane such that synthesis of Cox1p, Cox2p, and Cox3p would be colocalized in away that facilitates assembly of the core of the cytochrome c oxidase complex. In addition, we found interactions between Nam1p/Mtf2p and the translational activators, suggesting an organized delivery of mitochondrial mRNAs to the translation system.