Mitochondria synthesize only a small set of their proteins on endogenous mitoribosomes. These particles differ in structure and composition from both their bacterial 70S ancestors and cytosolic 80S ribosomes. Recently published high resolution structures of the human mitoribosome revealed the presence of three [2Fe-2S] clusters in the small and large subunits. Each of these clusters is coordinated in a bridging fashion by cysteine residues from two different mitoribosomal proteins. Here, we investigated the cell biological and biochemical roles of all three Fe/S clusters in mitochondrial function and assembly. First, we found a requirement of both early and late factors of the mitochondrial iron-sulfur cluster assembly machinery for protein translation indicating that not only the mitoribosome [2Fe-2S] clusters but also the [4Fe-4S] cluster of the mitoribosome assembly factor METTL17 are required for mitochondrial translation. Second, siRNA-mediated depletion of the cluster-coordinating ribosomal proteins bS18m, mS25 or mL66 and complementation with either the respective wild-type or cysteine-exchange proteins unveiled the importance of the clusters for assembly, stability, and function of the human mitoribosome. As a consequence, the lack of cluster binding to mitoribosomes impaired the activity of the mitochondrial respiratory chain complexes and led to altered mitochondrial morphology with a loss of cristae membranes. Finally, in silico investigation of the phylogenetic distribution of the cluster-coordinating cysteine motifs indicated their presence in most metazoan mitoribosomes, with exception of ray-finned fish. Collectively, our study highlights the functional need of mitochondrial Fe/S protein biogenesis for both protein translation and respiratory energy supply in most metazoan mitochondria.

中文翻译：

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三个 [2Fe-2S] 簇在人线粒体核糖体中的关键作用和保守性。


线粒体仅在内源性线粒体核糖体上合成一小部分蛋白质。这些颗粒在结构和组成上与其细菌 70S 祖先和胞质 80S 核糖体不同。最近发表的人类线粒体核糖体的高分辨率结构揭示了在小亚基和大亚基中存在三个 [2Fe-2S] 簇。这些簇中的每一个都由来自两种不同线粒体蛋白的半胱氨酸残基以桥接方式协调。在这里，我们研究了所有三个 Fe/S 簇在线粒体功能和组装中的细胞生物学和生化作用。首先，我们发现线粒体铁硫簇组装机制的早期和晚期因子都需要蛋白质翻译，这表明不仅线粒体核糖体 [2Fe-2S] 簇，而且线粒体核糖体组装因子 METTL17 的 [4Fe-4S] 簇都需要线粒体翻译。其次，siRNA 介导的簇配位核糖体蛋白 bS18m、mS25 或 mL66 的耗竭以及与相应的野生型或半年胱氨酸交换蛋白的互补揭示了簇对人核糖体组装、稳定性和功能的重要性。因此，缺乏与线粒体核糖体的簇结合损害了线粒体呼吸链复合物的活性，并导致线粒体形态改变，嵴膜丢失。最后，对簇配位半胱氨酸基序的系统发育分布的计算机研究表明，它们存在于大多数后生动物线粒体中，但射线鳍鱼除外。 总的来说，我们的研究强调了线粒体 Fe/S 蛋白生物发生对大多数后生动物线粒体蛋白质翻译和呼吸能量供应的功能需求。