线粒体解偶联蛋白UCP1的结构和功能解析

Mitochondrial uncoupling protein (UCPs) are exceptional type of transporters known to uncouple aerobic respiration from ADP phosphorylation by mediating H+ leak across the inner membrane. UCP-mediated H+ translocation requires free fatty acids (FAs) and purine nucleotides such as GDP inhibit this activity. Mounting evidences from biochemical and physiological studies of UCPs suggest that both enhancing and reducing the function of UCPs have a broad range of therapeutic implications including the treatment of obesity and diabetes, as well as reducing the generation of reactive oxygen species (ROS). But, no structural basis for either activation by FA or inhibition by GDP exists. In earlier study, we developed a functionally relevant sample system of UCP2 for NMR investigations and used it to solve a low resolution NMR structure of UCP2. As a timely follow-up to this development, we propose to provide the detailed structures of FA and GDP bindings to UCP1，which is one of the most important UCPs that is expressed in brown adipose tissue (BAT) and is responsible for nonshivering thermogenesis, while developing functional assays to address the mechanism of the interplay of FA and nucleotides in UCP1-driven proton translocation. Based on the knowledge from these studies, we will explore new strategies in developing specific enhancers of UCP1 activity as potential therapeutics.

解偶联蛋白(UCPs)是一类特殊的线粒体转运跨膜蛋白。这类蛋白在线粒体内膜上将质子转运进线粒体基质的同时，可以解偶联ATP合成的氧化磷酸化过程。UCPs的质子转运需要脂肪酸的辅助，而GDP可以抑制其活性。大量研究表明通过激活或者抑制UCPs的活性可以为治疗肥胖和糖尿病提供新的思路和手段。然而目前对UCPs的激活和抑制机制都了解得不清楚。前期工作中，我们建立一种新的核磁方法解析了UCP2的结构。在本项目中，我们将以UCPs中最重要的产热蛋白UCP1为研究对象，研究其结构与功能的关系。UCP1在棕色脂肪组织(BAT)中表达，完全介导了无颤抖产热来消耗能量，维持机体的能量代谢平衡。因此，探索UCP1通过转运质子调控BAT能量代谢的分子机理，揭示不同分子对UCP1的激活或抑制机制，将为基于棕色脂肪组织的肥胖治疗提供了理论依据。

UCP1是线粒体跨膜转运蛋白-解偶联蛋白(UCPs)中最重要的产热蛋白， 是治疗肥胖和糖尿病的潜在药物靶点。UCP1在线粒体内膜上，可以将质子转运进线粒体基质，同时解偶联ATP合成的氧化磷酸化过程。UCP1的质子转运需要脂肪酸的辅助，而GDP可以抑制其活性。然而脂肪酸是如何调控UCP1的质子转运非常得不清楚。本项目中我们提出了通过核磁共振方法研究UCP1转运质子过程中的分子机制。通过对UCP1核磁样品的筛选和制备，我们收集了UCP1的核磁数据，计算出了蛋白的二级结构，研究了脂肪酸与UCP1的相互作用，鉴定了脂肪酸与UCP1结合的关键位点，并通过脂质体实验验证了位点的重要性。该研究成果于2017年发表在国际期刊Structure上，完成了项目的预期计划。