Membrane Trafficking Pathways Mediate the Intracellular Distribution of Coenzyme Q

辅酶Q(CoQ)是能量新陈代谢所必需的，也是一种抗氧化剂，可以保护细胞膜免受氧气存在下的生命损伤。辅酶Q不溶于水，其功能依赖于它在膜中的存在。辅酶Q必须从制造辅酶Q的线粒体运输到整个细胞的其他膜上。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。辅酶Q的这种运动恢复了对细胞的能量产生和抗氧化保护。然而，负责这种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，它们在辅酶Q移动到需要它的地方起着至关重要的作用。这些蛋白质中的一种与辅酶Q紧密结合以帮助其移动，该项目将确定这种辅酶Q“伴侣”蛋白如何与细胞组件中的其他蛋白质一起工作，以实现辅酶Q的功能。研究人员还将鉴定他们发现的另外两种蛋白质，这两种蛋白质对辅酶Q的正确运动至关重要。阐明这三种蛋白的功能作用将促进我们对辅酶Q如何在细胞内运输的理解。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本科生，他们是科学发现的积极参与者。学生们将认识到，在细胞内膜的形成和运动中有许多尚未解决的问题，包括尚未发现的途径。学生将在当地会议以及国内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一种疏水性脂分子。它也是一种重要的抗氧化剂，可以保护细胞膜免受脂质过氧化。辅酶Q是在线粒体膜内合成的，必须运输到非线粒体膜。辅酶Q缺失的细胞补充外源辅酶Q，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，在那里它恢复呼吸电子传递的功能。然而，调节辅酶Q在细胞内分布的途径仍然知之甚少。为了促进我们对辅酶Q转运的了解，本项目将对辅酶Q在酿酒酵母中胞内分布所必需的三种蛋白质进行鉴定。研究人员将确定CoQ10的结构，这是一种从酵母到人类保存的CoQ结合蛋白。一种基于混合囊泡荧光的检测辅酶Q在囊泡之间移动的分析将被用于评估辅酶Q10多肽作为辅酶Q转运体的活性。该项目还旨在确定Coq11中保守的催化残基的功能。有证据表明，Coq11调节线粒体辅酶Q池，从而调节其在细胞内的分布。研究人员还发现，Vps1是调节辅酶Q运输所必需的。一组具有影响膜融合、分裂和膜转运的特定功能缺陷的VPS1突变体将被用来确定VPS1在辅酶Q运输中的重要功能作用(S)。这个项目将促进我们对辅酶Q和其他疏水分子如何在细胞内运输的理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.