PDF(Pubmed)
Abstract：
Mitochondrial translation depends on mRNA-specific activators. In Schizosaccharomyces pombe, DEAD-box protein Mrh5, pentatricopeptide repeat (PPR) protein Ppr4, Mtf2, and Sls1 form a stable complex (designated Mrh5C) required for translation of mitochondrial DNA (mtDNA)-encoded cox1 mRNA, the largest subunit of the cytochrome c oxidase complex. However, how Mrh5C is formed and what role Mrh5C plays in cox1 mRNA translation have not been reported. To address these questions, we investigated the role of individual Mrh5C subunits in the assembly and function of Mrh5C. Our results revealed that Mtf2 and Sls1 form a subcomplex that serves as a scaffold to bring Mrh5 and Ppr4 together. Mrh5C binds to the small subunit of the mitoribosome (mtSSU), but each subunit could not bind to the mtSSU independently. Importantly, Mrh5C is required for the association of cox1 mRNA with the mtSSU. Finally, we investigated the importance of the signature DEAD-box in Mrh5. We found that the DEAD-box of Mrh5 is required for the association of Mrh5C and cox1 mRNA with the mtSSU. Unexpectedly, this motif is also required for the interaction of Mrh5 with other Mrh5C subunits. Altogether, our results suggest that Mrh5 and Ppr4 cooperate in activating the translation of cox1 mRNA. Our results also suggest that Mrh5C activates the translation of cox1 mRNA by promoting the recruitment of cox1 mRNA to the mtSSU.
摘要：
线粒体翻译取决于mRNA特异性激活剂。在裂殖酵母中，DEAD-box蛋白Mrh5，五肽重复（PPR）蛋白Ppr4，Mtf2和Sls1形成线粒体DNA（mtDNA）编码的cox1mRNA翻译所需的稳定复合物（称为Mrh5C），细胞色素c氧化酶复合物的最大亚基。然而,Mrh5C是如何形成的以及Mrh5C在cox1mRNA翻译中起什么作用还没有报道。为了解决这些问题,我们研究了单个Mrh5C亚基在Mrh5C的组装和功能中的作用。我们的结果显示Mtf2和Sls1形成亚复合物，作为支架将Mrh5和Ppr4结合在一起。Mrh5C与丝裂体（mtSSU）的小亚基结合，但是每个亚基不能独立地与mtSSU结合。重要的是,mrh5C是cox1mRNA与mtSSU结合所必需的。最后,我们调查了Mrh5中DEAD-box签名的重要性。我们发现Mrh5的DEAD盒是Mrh5C和cox1mRNA与mtSSU结合所必需的。出乎意料的是,该基序对于Mrh5与其他Mrh5C亚基的相互作用也是必需的。总之,我们的结果表明，Mrh5和Ppr4合作激活cox1mRNA的翻译。我们的结果还表明，Mrh5C通过促进cox1mRNA向mtSSU的募集来激活cox1mRNA的翻译。
