Molecular Mechanism of Mitochondrial Membrane Transport

项目总结 线粒体钙(Ca~(2+))摄取是许多基本生理过程的中心。它能刺激三磷酸腺苷 在代谢需求增加的时候产生，并提供一个钙离子汇来调节钙离子介导的 小区内的本地信令。线粒体Ca~(2+)浓度也调节细胞凋亡和失调-- 具体地说，钙超载--是从神经元兴奋毒性到心力衰竭和 一些癫痫到肌营养不良症。然而，尽管线粒体钙摄取在正常人群中的重要性 生理和疾病，调节这一过程的分子机制是相对较新的发现和许多 一些根本性的问题仍有待回答。 钙离子内流到线粒体的主要途径是一种称为线粒体钙单转运蛋白的通道，它 包括无处不在的成孔亚基MCU，以及根据物种的不同，几个调节亚基 (在复合体中称为“Uniplex”)。这种新的通道对钙离子具有高度的选择性，其活性是紧密的 受细胞内钙离子浓度的调节。 我的团队最近确定了一种真菌微控制器的高分辨率晶体结构，它定义了一种新的 通道结构，并揭示了一个高亲和力的钙结合部位。此外，我们人类的冷冻-EM结构 Uniplex全息复合体揭示了它的结构，并暗示了它的调节机制。有了这些 结构和我们开发的方法，我的实验室正准备着手研究机械 对线粒体钙单转运蛋白的理解。 在这里，我们建议：1)阐明离子选择性、导电性和 2)了解通道门控和远程调制的机制；3)探索通道门控和远程调制的机制 钙离子依赖的单一复合体调控的分子基础。 这些结果将使我们对线粒体的活动和调节有更深入的了解。 钙单转运蛋白，扩大了我们对钙离子通道一般原理的理解。此外，他们应该 提供一个强大的框架来帮助设计MCU抑制剂，这可能代表着有希望的治疗方法 以MCU失调和线粒体钙超载为标志的疾病和病理。 好了！

PROJECT SUMMARY Mitochondrial calcium (Ca2+) uptake is central to many fundamental physiological processes. It stimulates ATP production during times of increased metabolic need and provides a Ca2+ sink to modulate Ca2+-mediated signaling locally within a cell. Mitochondrial Ca2+ concentrations also regulate apoptosis and dysregulation–– specifically, Ca2+ overload––is a hallmark of pathologies ranging from neuronal excitotoxicity to heart failure and some epilepsies to muscular dystrophies. Yet despite the importance of mitochondrial Ca2+ uptake in normal physiology and disease, the molecular machinery mediating this process is relatively recently identified and many fundamental questions remain to be answered. The main route of Ca2+ influx to mitochondria is a channel called mitochondrial calcium uniporter, which includes the ubiquitous pore-forming subunit MCU and, depending on the species, several regulatory subunits (termed “uniplex” when in complex). This novel channel is highly selective for Ca2+, and its activity is tightly regulated by cytosolic Ca2+ concentration. My group recently determined a high-resolution crystal structure for a fungal MCU that defined a novel channel architecture and revealed a high-affinity Ca2+-binding site. Moreover, our cryo-EM structure of the human uniplex holocomplex revealed its architecture and hints at the mechanisms by which it is regulated. With these structures and the methods we developed, my lab is uniquely poised to embark on the mechanistic understanding of the mitochondrial calcium uniporter. Here, we propose to: 1) elucidate the structural and biophysical basis of ion selectivity, conduction and inhibition; 2) understand mechanisms of the channel gating and the long-range modulation; and 3) probe the molecular basis of Ca2+-dependent regulation of the uniplex. These results will give us much needed mechanistic insights into the activity and regulation of mitochondrial calcium uniporter, expanding our understanding of general principles of Ca2+ channels. In addition, they should provide a strong framework to aid the design of MCU inhibitors, which may represent promising treatments for diseases and pathologies marked by MCU dysregulation and mitochondrial Ca2+ overload. !