De Silva Dasmanthie, Poliquin Sarah, Zeng Rui, Zamudio-Ochoa Angelica, Marrero Natalie, Perez-Martinez Xochitl, Fontanesi Flavia, Barrientos Antoni
Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
Departamento de Genetica Molecular, Instituto de Fisiología Celular, Universidad Nacional Autonoma de Mexico, Mexico City 04510, Mexico.
Nucleic Acids Res. 2017 Jun 20;45(11):6628-6643. doi: 10.1093/nar/gkx426.
Members of the DEAD-box family are often multifunctional proteins involved in several RNA transactions. Among them, yeast Saccharomyces cerevisiae Mss116 participates in mitochondrial intron splicing and, under cold stress, also in mitochondrial transcription elongation. Here, we show that Mss116 interacts with the mitoribosome assembly factor Mrh4, is required for efficient mitoribosome biogenesis, and consequently, maintenance of the overall mitochondrial protein synthesis rate. Additionally, Mss116 is required for efficient COX1 mRNA translation initiation and elongation. Mss116 interacts with a COX1 mRNA-specific translational activator, the pentatricopeptide repeat protein Pet309. In the absence of Mss116, Pet309 is virtually absent, and although mitoribosome loading onto COX1 mRNA can occur, activation of COX1 mRNA translation is impaired. Mutations abolishing the helicase activity of Mss116 do not prevent the interaction of Mss116 with Pet309 but also do not allow COX1 mRNA translation. We propose that Pet309 acts as an adaptor protein for Mss116 action on the COX1 mRNA 5΄-UTR to promote efficient Cox1 synthesis. Overall, we conclude that the different functions of Mss116 in the biogenesis and functioning of the mitochondrial translation machinery depend on Mss116 interplay with its protein cofactors.
DEAD-box家族成员通常是参与多种RNA事务的多功能蛋白质。其中，酵母酿酒酵母Mss116参与线粒体内含子剪接，在冷胁迫下还参与线粒体转录延伸。在这里，我们表明Mss116与线粒体核糖体组装因子Mrh4相互作用，是高效线粒体核糖体生物合成所必需的，因此也是维持线粒体整体蛋白质合成速率所必需的。此外，Mss116是高效COX1 mRNA翻译起始和延伸所必需的。Mss116与COX1 mRNA特异性翻译激活因子、五肽重复蛋白Pet309相互作用。在没有Mss116的情况下，Pet309几乎不存在，尽管线粒体核糖体可以加载到COX1 mRNA上，但COX1 mRNA翻译的激活受到损害。消除Mss116解旋酶活性的突变并不阻止Mss116与Pet309的相互作用，但也不允许COX1 mRNA翻译。我们提出，Pet309作为一种衔接蛋白，介导Mss116对COX1 mRNA 5΄-UTR的作用，以促进高效的Cox1合成。总体而言，我们得出结论，Mss116在线粒体翻译机器的生物合成和功能中的不同功能取决于Mss116与其蛋白质辅因子的相互作用。
