FUNCTIONAL ROLES OF COENZYME Q IN YEAST AND HUMAN CELLS

泛醌（辅酶Q或Q）在细胞中作为线粒体和血浆的氧化还原活性辅酶发挥作用 膜电子传递，以及必需的脂溶性抗氧化剂。人膳食 补充Q似乎在减缓神经和肌肉的进展方面具有有益的效果， 退化性疾病细胞有能力合成Q，但关于这些位点仍有很多东西有待了解。 它的合成，细胞间和细胞内运输的机制，以及它的调节和酶学， 生物合成拟议研究的目标是表征Q生物合成的多肽 途径，并确定Q生物合成的酶学。实验系统利用九个 互补组的Q缺陷（辅酶q）突变体的酵母酿酒酵母。公鸡 突变体为酵母和哺乳动物中Coq多肽的表征提供了基础。 Q-中间体的合成类似物提供了在分离和纯化中用作标准品的试剂。 Q中间体的鉴定，以及作为酶活性测定的底物。遗传和生化 有证据表明，酵母中Q的合成需要线粒体Coq多酶复合物。我们 建议鉴定多肽组分，并确定Q-中间体是否构成 这些复合物的重要脂质成分。辅酶Q生物合成的一个潜在的重要功能 复杂的是调节Q和Q-中间体通过途径的通量，这一过程可能 影响呼吸电子传递链的性能。我们还将描述十分之一的 酵母突变体的互补组。酵母coqIO突变体定义了一种独特的呼吸缺陷 因为线粒体表现出Q缺乏的特征表型，但具有正常的Q水平。这 一类突变体在与START结构域蛋白共享同源性的Q结合蛋白中具有缺陷。我们 将确定该Q结合蛋白是否在Q从其位点的递送中作为伴侣蛋白起作用。 合成到合适的位置进行呼吸电子传递。实验方法采用了 结合脂质化学、酵母遗传学和生物化学来描述生物合成步骤 负责在酵母和人类细胞中产生Q。

Ubiquinone (coenzyme Q or Q) functions in cells as a redox-active coenzyme of mitochondrial and plasma membrane electron transport, as well as an essential lipid soluble antioxidant. Human dietary supplementation with Q appears to have beneficial effects in slowing the progression of neuro- and muscle- degenerative diseases. Cells are capable of synthesizing Q, but much remains to be learned about the sites of its synthesis, mechanisms of inter- and intra-cellular transport, and the regulation and enzymology of its biosynthesis. The goals of the proposed research are to characterize the polypeptides of the Q biosynthetic pathway and to define the enzymology of Q biosynthesis. The experimental system takes advantage of nine complementation groups of Q-deficient (coq) mutants in the yeast Saccharomyces cerevisiae. The coq mutants provide the basis for the characterization of the Coq polypeptides in both yeast and mammals. Synthetic analogs of Q-intermediates provide reagents that serve both as standards in the isolation and identification of Q intermediates, and as substrates for assays of enzyme activities. Genetic and biochemical evidence indicate that synthesis of Q in yeast requires a mitochondrial Coq multienzyme complex. We propose to identify the polypeptide components, and to determine whether Q-intermediates constitute important lipid components of these complexes. A potentially important function of the Coq biosynthetic complex is to regulate the flux of Q and Q-intermediates through the pathway, a process that potentially impacts performance of the respiratory electron transport chain. We will also characterize a tenth complementation group of yeast mutants. The yeast coqIO mutant defines a unique respiratory deficiency because mitochondria exhibit the characteristic phenotype of Q-defiency, yet have normal levels of Q. This class of mutants has a defect in a Q binding protein that shares homology with START domain proteins. We will determine whether this Q binding protein functions as a chaperone in the delivery of Q from its site of synthesis to its proper location for respiratory electron transport. The experimental approach employs a combination of lipid chemistry, yeast genetics, and biochemistry to delineate the biosynthetic steps responsible for the production of Q in yeast and human cells.