Schizosaccharomyces pombe Mti2 and Mti3 act in conjunction during mitochondrial translation initiation
Schizosaccharomyces pombe Mti2 and Mti3 act in conjunction during mitochondrial translation initiation
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DOI：
10.1111/febs.15021
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发表时间：
2019-08-07
期刊：
影响因子：
5.4
通讯作者：
Huang, Ying
中科院分区：
文献类型：
--
作者：
Luo, Ying;Su, Ruyue;Huang, Ying
线粒体DNA编码ATP生成所必需的氧化磷酸化复合物的关键亚基。线粒体中的翻译起始需要两个一般因子，mtIF2和mtIF3，它们在细菌中的对应物是蛋白质合成所必需的。在这项研究中，我们报告了裂殖酵母裂殖酵母mtIF2（Mti2）和mtIF3（Mti3）的特性。mti2的缺失损害细胞在呼吸培养基上的生长。mti 2缺失突变体的生长缺陷可以通过表达IFM 1（Mti 2的酿酒酵母同源物）来抑制，这表明这两种蛋白质之间的功能保守性。mti2的缺失也损害线粒体蛋白质的合成。与mti2不同，mti3的缺失不影响细胞在呼吸介质上的生长和线粒体翻译。然而，mti3的缺失加剧了Delta mti2突变体的生长缺陷，这表明这两种蛋白在S.粟酒Mti2和Mti3都与线粒体核糖体（mitoribosome）的小亚基相关。mti2的破坏，而不是mti3，导致分裂的线粒体，也取消了Mti3结合的小亚基的线粒体。我们的研究结果表明，Mti2和Mti3以顺序的方式结合到线粒体的小亚基，Mti3促进Mti2在线粒体翻译起始中的功能。我们的研究结果也支持了线粒体翻译起始因子的重要性在生物体之间存在差异的观点。
Mitochondrial DNA encodes key subunits of the oxidative phosphorylation complexes essential for ATP production. Translation initiation in mitochondria requires two general factors, mtIF2 and mtIF3, whose counterparts in bacteria are essential for protein synthesis. In this study, we report the characterization of the fission yeast Schizosaccharomyces pombe mtIF2 (Mti2) and mtIF3 (Mti3). Deletion of mti2 impairs cell growth on the respiratory medium. The growth defect of the mti2 deletion mutant can be suppressed by expressing IFM1, the Saccharomyces cerevisiae homolog of Mti2, demonstrating functional conservation between the two proteins. Deletion of mti2 also impairs mitochondrial protein synthesis. Unlike mti2, deletion of mti3 does not affect cell growth on respiratory media and mitochondrial translation. However, deletion of mti3 exacerbates the growth defect of the Delta mti2 mutant, suggesting that the two proteins have distinct, but partially overlapping functions during the process of mitochondrial translation initiation in S. pombe. Both Mti2 and Mti3 are associated with the small subunit of the mitochondrial ribosome (mitoribosome). Disruption of mti2, but not mti3, causes dissociation of the mitoribosome and also abolishes Mti3 binding to the small subunit of the mitoribosome. Our results suggest that Mti2 and Mti3 bind in a sequential manner to the small subunit of the mitoribosome and that Mti3 facilitates the function of Mti2 in mitochondrial translation initiation. Our findings also support the view that the importance of the mitochondrial translation initiation factors varies among the organisms.