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，可以保护细胞膜免受在氧气存在下的生命所造成的损害。 辅酶Q不溶于水，其功能依赖于其在膜中的存在。 辅酶Q必须从其制造的线粒体运输到整个细胞的其他膜。细胞也能够从细胞外摄取辅酶Q，并将其转运到细胞内的细胞膜。 辅酶Q的这种运动恢复能量生产和抗氧化保护细胞。 然而，负责这种辅酶Q运动的机制仍然是神秘的。 在这个项目中，研究人员已经确定了三种蛋白质，它们在辅酶Q运动到需要的地方中起着关键作用。 其中一种蛋白质与辅酶Q紧密结合以帮助其移动，该项目将确定这种辅酶Q“伴侣”蛋白如何与细胞组分中的其他蛋白质一起工作以实现辅酶Q功能。 研究人员还将描述他们发现的另外两种蛋白质，它们对辅酶Q的正确运动至关重要。 阐明这三种蛋白质的功能作用将促进我们对辅酶Q如何在整个细胞中转运的理解。该项目还将培养研究生和本科生成为研究人员。研究生将教授和指导本科生，他们是科学发现的积极参与者。 学生们会意识到，在细胞膜的形成和运动中有许多未解决的问题，包括尚未发现的路线。学生将在当地会议以及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性脂质分子。 它也是一种重要的抗氧化剂，保护细胞膜免受脂质过氧化作用。 辅酶Q在线粒体内膜内合成，必须运输到非线粒体膜。 补充有外源性辅酶Q的辅酶Q缺陷细胞能够摄取这种不溶性脂质并将其从质膜转运到线粒体内膜，在那里它恢复呼吸电子转运的功能。 然而，介导辅酶Q的细胞内分布的途径仍然知之甚少。为了推进我们对辅酶Q运输的理解，本项目将表征辅酶Q在酿酒酵母细胞内分布所必需的三种蛋白质。 研究人员将确定Coq10的结构，Coq10是一种从酵母到人类保守的辅酶Q结合蛋白。 将使用检测CoQ在囊泡之间移动的基于混合囊泡荧光的测定来评估Coq10多肽作为CoQ转运蛋白的活性。 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调节线粒体辅酶Q库，因此，它的细胞内分布。 研究人员还发现，Vps1是介导辅酶Q转运所必需的。 一组vps1突变体的特定功能，影响膜融合，裂变和内膜运输的缺陷将被用来确定功能的作用（S）的Vps1辅酶Q运输的重要。 该项目将促进我们对辅酶Q和其他疏水分子如何在细胞中转运的理解。该奖项反映了NSF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.