NSUN4 is a dual function mitochondrial protein required for both methylation of 12S rRNA and coordination of mitoribosomal assembly.
NSUN4 is a dual function mitochondrial protein required for both methylation of 12S rRNA and coordination of mitoribosomal assembly.
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DOI：
10.1371/journal.pgen.1004110
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发表时间：
2014-02
期刊：
影响因子：
4.5
通讯作者：
Ruzzenente B
中科院分区：
文献类型：
--
作者：
Metodiev MD;Spåhr H;Loguercio Polosa P;Meharg C;Becker C;Altmueller J;Habermann B;Larsson NG;Ruzzenente B
哺乳动物线粒体核糖体的生物发生需要小亚基（SSU）和大亚基（LSU）的协调成熟。我们在这里证明，m5C甲基转移酶NSUN4与MTERF4形成复合物，在线粒体核糖体生物发生中是必不可少的，因为线粒体翻译在条件性NSUN4小鼠敲除中被废除。亚硫酸氢盐处理RNA的深度测序显示，NSUN4甲基化SSU的12S rRNA （m5C911）中的胞嘧啶911。令人惊讶的是，NSUN4不需要MTERF4来生成这个修改。相反，需要NSUN4/MTERF4复合体来组装SSU和LSU以形成单体。因此，NSUN4是一种双重功能蛋白，一方面是12S rRNA甲基化所必需的，另一方面与MTERF4相互作用以促进单体组装。目前的数据表明，NSUN4在控制核糖体生物发生的最后一步中起关键作用，以确保只组装成熟的SSU和LSU。线粒体在细胞中执行许多基本功能，包括通过氧化磷酸化（OXPHOS）系统合成ATP。正常的线粒体功能需要两个基因组的协调表达：线粒体自身的基因组（mtDNA）编码13个呼吸链亚基，这些亚基对OXPHOS系统具有重要的结构和功能作用，而核基因组编码其余的约80个亚基。线粒体dna编码的多肽是在线粒体基质中的线粒体核糖体（mitoribosomes）上合成的。复杂线粒体翻译装置的生物发生、维持和调节对细胞能量稳态至关重要，但人们对其了解甚少。在这里，我们发现编码线粒体m5c -甲基转移酶的Nsun4基因失活会导致胚胎死亡，而心脏组织特异性的Nsun4破坏会导致心肌病和线粒体功能障碍。通过对亚硫酸氢盐处理过的RNA进行测序，我们发现NSUN4在小核糖体亚基的12S rRNA中甲基化C911。令人惊讶的是，NSUN4可以自己完成这种rRNA修饰，而与其伴侣蛋白MTERF4的相互作用是组装功能性核糖体所必需的。因此，NSUN4在核糖体成熟中具有双重作用，并执行重要的最后质量控制步骤，以确保只有成熟的核糖体亚基被组装成功能性核糖体。
Biogenesis of mammalian mitochondrial ribosomes requires a concerted maturation of both the small (SSU) and large subunit (LSU). We demonstrate here that the m5C methyltransferase NSUN4, which forms a complex with MTERF4, is essential in mitochondrial ribosomal biogenesis as mitochondrial translation is abolished in conditional Nsun4 mouse knockouts. Deep sequencing of bisulfite-treated RNA shows that NSUN4 methylates cytosine 911 in 12S rRNA (m5C911) of the SSU. Surprisingly, NSUN4 does not need MTERF4 to generate this modification. Instead, the NSUN4/MTERF4 complex is required to assemble the SSU and LSU to form a monosome. NSUN4 is thus a dual function protein, which on the one hand is needed for 12S rRNA methylation and, on the other hand interacts with MTERF4 to facilitate monosome assembly. The presented data suggest that NSUN4 has a key role in controlling a final step in ribosome biogenesis to ensure that only the mature SSU and LSU are assembled. Mitochondria perform a number of essential functions in the cell, including synthesis of ATP via the oxidative phosphorylation (OXPHOS) system. Normal mitochondrial function requires coordinated expression of two genomes: mitochondria's own genome (mtDNA), which encodes 13 respiratory chain subunits with essential structural and functional roles for the OXPHOS system, and the nuclear genome encoding the remaining ∼80 subunits. The mtDNA-encoded polypeptides are synthesized on mitochondrial ribosomes (mitoribosomes) located in the mitochondrial matrix. Biogenesis, maintenance and regulation of the complex mitochondrial translation apparatus are poorly understood despite its fundamental importance for cellular energy homeostasis. Here, we show that inactivation of the Nsun4 gene, encoding a mitochondrial m5C-methyltransferase, causes embryonic lethality, whereas tissue-specific disruption of Nsun4 in the heart causes cardiomyopathy with mitochondrial dysfunction. By performing sequencing of bisulfite-treated RNA we report that NSUN4 methylates C911 in 12S rRNA of the small ribosomal subunit. Surprisingly, NSUN4 can on its own perform this rRNA modification, whereas interaction with its partner protein MTERF4 is required for assembly of functional ribosomes. NSUN4 thus has dual roles in ribosome maturation and performs an important final quality control step to ensure that only mature mitoribosomal subunits are assembled into functional ribosomes.
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影响因子：
29
作者：
Camara, Yolanda;Asin-Cayuela, Jorge;Larsson, Nils-Goran
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作者：
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