Long-lived proteins (LLPs) have recently emerged as vital components of intracellular structures whose function is coupled to long-term stability. Mitochondria are multifaceted organelles, and their function hinges on efficient proteome renewal and replacement. Here, using metabolic stable isotope labeling of mice combined with mass spectrometry (MS)–based proteomic analysis, we demonstrate remarkable longevity for a subset of the mitochondrial proteome. We discovered that mitochondrial LLPs (mt-LLPs) can persist for months in tissues harboring long-lived cells, such as brain and heart. Our analysis revealed enrichment of mt-LLPs within the inner mitochondrial membrane, specifically in the cristae subcompartment, and demonstrates that the mitochondrial proteome is not turned over in bulk. Pioneering cross-linking experiments revealed that mt-LLPs are spatially restricted and copreserved within protein OXPHOS complexes, with limited subunit exchange throughout their lifetimes. This study provides an explanation for the exceptional mitochondrial protein lifetimes and supports the concept that LLPs provide key structural stability to multiple large and dynamic intracellular structures.

中文翻译：

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小鼠心脏和大脑中的长寿线粒体嵴蛋白

长寿蛋白（LLP）最近已成为细胞内结构的重要组成部分，其功能与长期稳定性相关。线粒体是多方面的细胞器，其功能取决于有效的蛋白质组更新和替换。在这里，我们利用小鼠的代谢稳定同位素标记结合基于质谱（MS）的蛋白质组分析，证明了线粒体蛋白质组的一个子集具有显着的寿命。我们发现线粒体 LLP (mt-LLP) 可以在含有长寿细胞的组织（例如大脑和心脏）中持续存在数月。我们的分析揭示了线粒体内膜内，特别是嵴亚室中 mt-LLP 的富集，并证明线粒体蛋白质组并未大量翻转。开创性的交联实验表明，mt-LLP 在空间上受到限制，并共同保存在蛋白质 OXPHOS 复合物中，在其整个生命周期中亚基交换有限。这项研究为线粒体蛋白的特殊寿命提供了解释，并支持 LLP 为多个大型动态细胞内结构提供关键结构稳定性的概念。