Molecular Biophysics of Mitochondrial Membranes

项目摘要 这个项目的重点是了解控制体内能量转换的分子机制。 细胞动力装置，线粒体。离子和代谢物通过内部线粒体的运输 膜是线粒体生理学的基础。在这里，我们研究涉及到的分子机制 线粒体被动摄取H+(“线粒体H+漏”)和钙(“线粒体钙摄取”)向下 跨内线粒体膜的负电压()。线粒体H+泄漏是 用于将线粒体底物的化学能转化为热。线粒体钙摄取使 胞浆钙瞬变过程中钙离子进入线粒体刺激Krebs细胞内钙依赖酶 循环和线粒体能量转换。线粒体H+漏和钙摄取是由 线粒体内膜的特殊完整蛋白称为解偶联蛋白(UCPs)和 相应的线粒体钙单转运体(MCU)。UCPs的分子和功能表征 由于无法测量线粒体内部的H+和Ca~(2+)电流，MCU一直很困难 直接用膜分离。我们解决了这一重大技术障碍，并开发了一种直接贴片的方法-- 钳位记录整个线粒体膜上的UCP和MCU电流。使用这个 方法，我们建议处理UCP和MCU内部的结构-功能关系，以理解 通过这些膜转运蛋白控制H+和Ca~(2+)转运的分子机制。为 ，我们计划确定游离脂肪酸，内源性UCPs激活剂，导致 通过UCPs的H+转运。我们还提议开发能够激活H+泄漏的新一代药物 通过UCP，用于治疗II型糖尿病、肥胖症和脂肪肝。对于MCU，我们建议 揭示MCU异常高的钙离子选择性的分子机制 内向整流(钙离子单向渗透到线粒体)，以及胞浆对MCU的增强作用 Ca2+。这项研究将解决生物能量学领域的几个长期存在的问题，并最终将 在治疗和研究目的上实现对关键线粒体功能的药理学控制。

Project Summary This project is focused on understanding of the molecular mechanisms that control energy conversion within the cell power plant, the mitochondrion. Transport of ion and metabolites across the inner mitochondrial membrane is the foundation of mitochondrial physiology. Here we study the molecular mechanisms involved in passive uptake of H+ (“mitochondrial H+ leak”) and Ca2+ (“mitochondrial Ca2+ uptake”) into mitochondria down the negative voltage () across the inner mitochondrial membrane. The mitochondrial H+ leak is responsible for the conversion of chemical energy of mitochondrial substrates into heat. The mitochondrial Ca2+ uptake lets Ca2+ enter mitochondria during cytosolic Ca2+ transients to stimulate Ca2+-dependent enzymes of the Krebs cycle and mitochondrial energy conversion. The mitochondrial H+ leak and Ca2+ uptake are mediated by specialized integral proteins of the inner mitochondrial membrane called uncoupling proteins (UCPs) and mitochondrial Ca2+ uniporter (MCU) correspondingly. The molecular and functional characterization of UCPs and MCU has been difficult due to the inability to measure H+ and Ca2+ currents across the inner mitochondrial membrane directly. We have resolved this major technical barrier and developed a method for direct patch- clamp recording of UCP and MCU currents across the whole inner mitochondrial membrane. Using this method, we propose to address the structure-function relations within UCPs and MCU to understand the molecular mechanisms that govern H+ and Ca2+ translocation via these membrane transport proteins. For UCPs, we plan to identify the mechanisms by which free fatty acids, the endogenous UCPs activators, cause H+ translocation via UCPs. We also propose to develop a new generation of drugs that can activate H+ leak via UCP and be used for the treatment of type II diabetes, obesity, and fatty liver. For MCU, we propose to reveal the molecular mechanisms responsible for the exceptionally high Ca2+ selectivity of MCU, the MCU inward rectification (one-way permeation of Ca2+ into mitochondria), and the MCU potentiation by cytosolic Ca2+. This research will resolve several long-standing problems in the field of bioenergetics and will eventually enable pharmacological control of key mitochondrial functions in therapeutic and research purposes.