Respiratory chains are crucial for cellular energy conversion and consist of multi‐subunit complexes that can assemble into supercomplexes. These structures have been intensively characterized in various organisms, but their physiological roles remain unclear. Here, we elucidate their function by leveraging a high‐resolution structural model of yeast respiratory supercomplexes that allowed us to inhibit supercomplex formation by mutation of key residues in the interaction interface. Analyses of a mutant defective in supercomplex formation, which still contains fully functional individual complexes, show that the lack of supercomplex assembly delays the diffusion of cytochrome c between the separated complexes, thus reducing electron transfer efficiency. Consequently, competitive cellular fitness is severely reduced in the absence of supercomplex formation and can be restored by overexpression of cytochrome c. In sum, our results establish how respiratory supercomplexes increase the efficiency of cellular energy conversion, thereby providing an evolutionary advantage for aerobic organisms.

中文翻译：

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呼吸超复合物通过减少细胞色素 c 扩散距离来增强电子传输


呼吸链对于细胞能量转换至关重要，由可组装成超复合物的多亚基复合物组成。这些结构在各种生物体中已被深入表征，但其生理作用仍不清楚。在这里，我们通过利用酵母呼吸超复合物的高分辨率结构模型来阐明它们的功能，该模型使我们能够通过相互作用界面中关键残基的突变来抑制超复合物的形成。对超复合物形成缺陷的突变体（仍包含功能齐全的单个复合物）的分析表明，超复合物组装的缺乏延迟了细胞色素c在分离的复合物之间的扩散，从而降低了电子转移效率。因此，在没有超级复合物形成的情况下，竞争性细胞适应性会严重降低，并且可以通过细胞色素c的过度表达来恢复。总之，我们的结果确定了呼吸超级复合物如何提高细胞能量转换的效率，从而为需氧生物提供进化优势。