Molecular Mechanisms of Mitochondrial Biogenesis

项目总结 线粒体是内共生的双膜结合细胞器，为细胞提供 通过氧化呼吸产生的能量。线粒体也是细胞新陈代谢的主要枢纽， 参与多种重要途径，包括细胞信号、先天免疫反应和细胞凋亡。 线粒体功能障碍与衰老和许多疾病有关，是一个潜在的致病因素 神经退行性疾病。&gt；1000种线粒体蛋白大多由核基因组编码， 因此，在作为胞质核糖体的前体合成后不久，从胞浆中输入。因此， 线粒体蛋白输入是生物发生和功能维持所必需的过程 线粒体。进口过程主要由两个普遍保守的膜复合体介导，即 外膜(TOM)复合体转位酶和内膜(TIM)复合体转位酶。 TOM复合体介导前体蛋白跨外线粒体的初始移位 膜，TIM复合体进一步将前体蛋白转移到内部线粒体 薄膜。TIM复合体还负责将许多完整的膜蛋白整合到 内膜。目前，人们对TOM和TIM复合体是如何调节这些的知之甚少 移位过程。在目前的提案中，我们的目标是解决以下主要悬而未决的问题 TOM和TIM复合体的蛋白质输入机制，利用结构、生化和生物物理 接近了。这些问题包括转位酶复合体如何识别它们的客户 蛋白质，它们如何在膜上形成蛋白质转运的路径，分子间的相互作用是什么 并推动蛋白质转位，以及转位酶复合体是如何受到调控的。特别是，我们将 进行几项冷冻电子显微镜(Cryo-EM)研究，以显示不同组织中的转位酶复合体 功能状态，包括底物参与状态，并深入了解它们对底物的作用机制 参与和构象变化。这些研究的结果将从根本上推动我们的 了解线粒体生物学，并为开发新的治疗方法提供新的见解 线粒体相关疾病，如神经退行性疾病。

PROJECT SUMMARY Mitochondria are endosymbiotically-derived double membrane-bound organelles which provide cells with energy via oxidative respiration. Mitochondria also serve as a major hub for cellular metabolism and are involved in numerous vital pathways, including cell signaling, innate immune response, and apoptosis. Dysfunction of mitochondria is implicated in aging and many diseases and is a potential causative factor in neurodegenerative diseases. Most of >1,000 mitochondrial proteins are encoded by the nuclear genome and thus are imported from the cytosol shortly after being synthesized as precursors on cytosolic ribosomes. Thus, mitochondrial protein import is an essential process required for biogenesis and functional maintenance of mitochondria. The import process is mainly mediated by two universally conserved membrane complexes, the translocase of the outer membrane (TOM) complex and the translocase of the inner membrane (TIM) complex. The TOM complex mediates the initial translocation of precursor proteins across the outer mitochondrial membrane, and the TIM complex further translocates the precursor proteins across the inner mitochondrial membrane. The TIM complex is also responsible for integration of many integral membrane proteins to the inner membrane. Currently, it is poorly understood how the TOM and TIM complexes mediate these translocation processes. In the current proposal, we aim to address central outstanding questions about protein import mechanisms by the TOM and TIM complexes, using structural, biochemical, and biophysical approaches. These questions include how the translocase complexes specifically recognize their client proteins, how they form a path for protein translocation in the membranes, what are the molecular interactions and forces driving protein translocation, and how the translocase complexes are regulated. In particular, we will perform several cryo-electron microscopy (cryo-EM) studies to visualize the translocase complexes in different functional states, including substrate-engaged states, and gain insights into their mechanisms for substrate engagement and conformational changes. The outcomes of these studies will fundamentally advance our understanding of mitochondrial biology and provide new insights to develop novel approaches to treat mitochondrial-associated diseases, such as neurodegenerative diseases.