Membrane Trafficking Pathways Mediate the Intracellular Distribution of Coenzyme Q

辅酶Q （CoQ）是能量代谢所必需的，也是一种抗氧化剂，保护细胞膜免受生命中氧气的损害。辅酶q不溶于水，它的功能依赖于它在膜中的存在。辅酶q必须从制造它的线粒体运输到整个细胞的其他膜。细胞也能够从细胞外吸收辅酶q并将其运输到细胞内的膜上。这种CoQ的运动恢复了细胞的能量生产和抗氧化保护。然而，导致这种CoQ运动的机制仍然是个谜。在这个项目中，研究人员已经确定了三种蛋白质，它们在CoQ运动到需要的地方起着至关重要的作用。其中一种蛋白质与CoQ紧密结合以帮助其移动，该项目将确定这种CoQ“伴侣”蛋白质如何与细胞成分中的其他蛋白质一起工作以使CoQ发挥作用。研究人员还将描述他们发现的对CoQ的正确运动至关重要的另外两种蛋白质。阐明这三种蛋白质的功能作用将促进我们对CoQ如何在整个细胞中运输的理解。该项目还将培养研究生和本科生作为研究人员。研究生将教授和指导积极参与科学发现的本科生。学生将认识到，在膜的形成和细胞内的运动中有许多尚未解决的问题，包括尚未发现的路线。学生将在当地会议、国家和国际会议上展示他们的研究成果。辅酶Q （CoQ）是线粒体呼吸能量代谢所必需的疏水脂质分子。它也是一种重要的抗氧化剂，保护细胞膜免受脂质过氧化。辅酶q在线粒体内膜内合成，必须运输到非线粒体膜。CoQ缺陷的细胞补充了外源CoQ，能够吸收这种不溶性脂质，并将其从质膜运输到线粒体内膜，在那里恢复呼吸电子传递的功能。然而，介导CoQ细胞内分布的途径仍然知之甚少。为了提高我们对CoQ运输的理解，本项目将对酵母菌CoQ细胞内分布所必需的三种蛋白质进行表征。研究人员将确定Coq10的结构，这是一种coq结合蛋白，从酵母到人类都是保守的。一种基于混合囊泡荧光的检测囊泡间辅酶q移动的方法将用于评估辅酶q10多肽作为辅酶q转运体的活性。该项目还旨在确定Coq11中保守催化残基的功能。有证据表明，Coq11调节线粒体CoQ库，从而调节其细胞内分布。研究人员还发现Vps1是介导CoQ转运所必需的。一组具有影响膜融合、裂变和膜运输的特定功能缺陷的vps1突变体将被用来确定vps1对CoQ运输的重要功能作用。这个项目将推进我们对CoQ和其他疏水分子如何在细胞中运输的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Coenzyme Q (CoQ) is essential for energy metabolism and also serves as an antioxidant that protects cell membranes from damage that accrues from life in the presence of oxygen. CoQ is insoluble in water, and its functions rely on its presence in the membrane. CoQ must be transported from the mitochondria where it is made, to other membranes throughout the cell. Cells are also able to take up CoQ from outside the cell and transport it to membranes within the cell. Such movement of CoQ restores energy production and antioxidant protection to cells. However, the mechanisms responsible for such CoQ movement remain mysterious. In this project investigators have identified three proteins that play crucial roles in CoQ movement to where it is needed. One of these proteins binds tightly to CoQ to help it move, and this project will identify how this CoQ “chaperone” protein works with other proteins in the cell components to enable CoQ function. The investigators will also characterize two other proteins they discovered that are essential for correct movement of CoQ. Elucidating the functional roles of these three proteins will advance our understanding of how CoQ is transported throughout the cell. This project will also train graduate and undergraduate students as researchers. Graduate students will teach and mentor undergraduate students, who are active participants in the scientific discoveries. Students will appreciate that there are many unsolved problems in membrane formation and movement within the cell, including routes yet to be discovered. Students will present their research findings at local conferences and at national and international meetings. Coenzyme Q (CoQ) is a hydrophobic lipid molecule essential for mitochondrial respiratory energy metabolism. It also serves as a vital antioxidant that protects cellular membranes from lipid peroxidation. CoQ is synthesized within the inner mitochondrial membrane and must be trafficked to non-mitochondrial membranes. CoQ-deficient cells supplemented with exogenously supplied CoQ are able to take up this insoluble lipid and transport it from the plasma membrane to the mitochondrial inner membrane, where it restores the function of respiratory electron transport. However, the pathways that mediate the intracellular distribution of CoQ remain poorly understood. In order to advance our understanding of CoQ trafficking, this project will characterize three proteins essential for the intracellular distribution of CoQ in the yeast Saccharomyces cerevisiae. The investigators will determine the structure of Coq10, a CoQ-binding protein conserved from yeast to humans. A mixed-vesicle fluorescence-based assay that detects movement of CoQ between vesicles will be used to assess the activity of the Coq10 polypeptide as a CoQ transporter. The project also aims to determine the function of conserved catalytic residues in Coq11. Evidence suggests that Coq11 modulates the mitochondrial CoQ pool and hence, its intracellular distribution. The investigators also discovered that Vps1 is required to mediate CoQ transport. A panel of vps1 mutants with defects in specific functions that affect membrane fusion, fission, and endomembrane trafficking will be used to identify the functional role(s) of Vps1 important for CoQ transport. This project will advance our understanding of how CoQ, and other hydrophobic molecules, are transported throughout cells.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.