FUNCTIONAL ROLES OF UBIQUINONE IN YEAST AND HUMAN CELLS

泛醌在酵母和人体细胞中的功能作用

• 批准号: 2183545
• 负责人: CATHERINE FREITAG CLARKE
• 金额: $ 17.43万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-04-01 至 1996-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2183545
• 关键词: Saccharomyces cerevisiae; carbon; cellular respiration; chemical structure function; enzyme mechanism; fungal genetics; gene complementation; genetic regulation; human tissue; laboratory rabbit; methyltransferase; microorganism growth; molecular cloning; mutant; nucleic acid sequence; organelles; radionuclides; radiotracer; ubiquinone

Ubiquinone is an essential component of the mitochondrial respiratory chain. Although present in all organs and tissues of animals, the concentration of ubiquinone is highest in heart and skeletal muscle. Ubiquinone synthesis and localization is usually considered to be limited to the inner mitochondrial membrane. However, a recent report has shown that ubiquinone is also synthesized on the ER of rat liver. In fact, Golgi vesicles and lysosomes, membranes in close communication with the ER, contain more ubiquinone on a protein basis that mitochondria. The function ubiquinone might be serving in these other intracellular compartments is not clear. Since ubiquinone biosynthesis in yeast and other eukaryotes have share the same pathway, the proposed studies take advantage of a class of respiratory defective mutants of Saccharomyces cerevisiae that are deficient in ubiquinone. The mutants fall into nine complementation groups, and will be used to characterize the regulation of ubiquinone biosynthesis and to determine the function of ubiquinone in nonmitochondrial compartments. Yeast mutants defective in 3,4-dihydroxy-5-hexaprenyl benzoate (DHHB) methyltransferase, a regulated enzyme of ubiquinone synthesis, will allow the gene encoding this enzyme to be cloned. The gene will provide the biochemical tools necessary to study the regulation of DHHB methyltransferase activity and its role in the regulation of ubiquinone biosynthesis. DHHB methyltransferase null mutants will be constructed to assess whether a lack of mitochondrial ubiquinone synthesis affects ubiquinone auxotrophic or synthesis in other organelles. The lesions in other ubiquinone auxotrophic mutants will be identified. The yeast mutant strains will be used as vehicles for isolating human cDNA clones, either by homology probing strategies or by functional complementation. Experimental therapies have been reported in which administration of ubiquinone to patients with heart disease, mitochondrial encephalomyopathies, or with Kearns-Sayre indicates that ubiquinone may aid in preventing mevinolin induced muscle weakness, a rare but major side effect of hypocholesterolemic therapy with lovastatin. The mechanisms by which ubiquinone mediates these effects is not clear. The proposed studies should increase our understanding of how ubiquinone functions in these clinical therapies.

泛氨基酮是线粒体呼吸道的重要组成部分 链。 尽管存在于动物的所有器官和组织中 泛氨基酮的浓度在心脏和骨骼肌上最高。 泛氨基酮的合成和定位通常被认为是有限的 到内部线粒体膜。 但是，最近的报告表明 该泛酮酮也已在大鼠肝脏的ER上合成。 实际上，高尔基 囊泡和溶酶体，与ER密切交流的膜， 在蛋白质基础上含有更多的泛氨酸酮。 功能 在这些其他细胞内室中可能会使用泛氨基酮 不清楚。 由于酵母和其他真核生物中的泛素酮生物合成已共享 同样的途径，拟议的研究利用了一类呼吸系统 酿酒酵母的有缺陷的突变体不足 泛素酮。 突变体属于九个互补组，将是 用于表征泛氨酸酮生物合成的调节和 确定泛氨基酮在非蒙蒙蒙软骨区室中的功能。 酵母突变体在3,4-二羟基-5-己糖酸酯（DHHB）中有缺陷 甲基转移酶是泛氨基合成的调节酶，将允许 编码该酶的基因要克隆。 该基因将提供 研究DHHB调节所需的生化工具 甲基转移酶活性及其在泛氨基酮调节中的作用 生物合成。 DHHB甲基转移酶无效突变体将被构造为 评估缺乏线粒体泛氨基酮合成是否影响 其他细胞器中的泛酮营养性或合成。 病变 将鉴定出其他泛酮可营养突变体。 酵母突变体 菌株将用作隔离人cDNA克隆的车辆，要么由 同源探测策略或通过功能补充。 已经报道了实验疗法 心脏病，线粒体患者的泛氨基酮 脑病或与Kearns-Sayre一起表明泛氨基酮可能有助于 在防止甲醇蛋白诱发的肌肉无力时，这是一种罕见但主要的一面 洛伐他汀降胆固醇疗法的作用。 这些机制 泛氨酮介导这些作用尚不清楚。 提出的研究 应该增加我们对泛氨基酮在这些功能中的作用的理解 临床疗法。