Genetic evidence for a multi-subunit complex in the O-methyltransferase steps of coenzyme Q biosynthesis
Genetic evidence for a multi-subunit complex in the O-methyltransferase steps of coenzyme Q biosynthesis
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DOI：
10.1016/s1388-1981(00)00019-6
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发表时间：
2000-04-12
影响因子：
4.8
通讯作者：
Clarke, CF
中科院分区：
文献类型：
--
作者：
Hsu, AY;Do, TQ;Clarke, CF
Coq3 O-甲基转移酶执行辅酶 Q（泛醌）生物合成中的两个 O-甲基化步骤。 Coq3 O-甲基转移酶活性和表达对其他七种 COQ 基因产物的依赖程度已得到研究。已经制备了一组在辅酶 Q 生物合成（COQ1-COQ8）所需的每个基因中含有无效突变的酵母突变菌株。线粒体已从酵母 cog 突变体集合的每个成员、野生型亲本菌株和带有 ATP2 或 COR1 基因缺失的呼吸缺陷突变体中分离出来。后面这些菌株构成 Q 充足、呼吸缺陷的对照。分析了每种线粒体制剂的 COQ3 编码的 O-甲基转移酶活性和 Coq3 多肽的稳态水平。研究结果表明，需要其他 COQ 基因产物的存在才能观察到正常水平的 O-甲基转移酶活性和 Coq3 多肽。然而，相对于野生型或呼吸缺陷对照菌株，COQ3稳态RNA水平在任何cog突变体中均未降低，这表明Coq3多肽的翻译速率降低或稳定性降低。这些数据与Coq多肽（或由Coq多肽形成的Q-中间体）参与多亚基复合物一致。我们的假设是，任何一种 COQ 基因产物的缺陷都会导致有缺陷的复合物，其中 Coq3 多肽变得不稳定。 (C) 2000 Elsevier Science B.V. 保留所有权利。
Coq3 O-methyltransferase carries out both O-methylation steps in coenzyme Q (ubiquinone) biosynthesis. The degree to which Coq3 O-methyltransferase activity and expression are dependent on the other seven COQ gene products has been investigated. A panel of yeast mutant strains harboring null mutations in each of the genes required for coenzyme Q biosynthesis (COQ1-COQ8) have been prepared. Mitochondria have been isolated from each member of the yeast cog mutant collection, from the wild-type parental strains and from respiratory deficient mutants harboring deletions in ATP2 or COR1 genes. These latter strains constitute Q-replete, respiratory deficient controls. Each of these mitochondrial preparations has been analyzed for COQ3-encoded O-methyltransferase activity and steady state levels of Coq3 polypeptide. The findings indicate that the presence of the other COQ gene products is required to observe normal levels of O-methyltransferase activity and the Coq3 polypeptide. However, COQ3 steady state RNA levels are not decreased in any of the cog mutants, relative to either wild-type or respiratory deficient control strains, suggesting either a decreased rate of translation or a decreased stability of the Coq3 polypeptide. These data are consistent with the involvement of the Coq polypeptides (or the Q-intermediates formed by the Coq polypeptides) in a multi-subunit complex. It is our hypothesis that a deficiency in any one of the COQ gene products results in a defective complex in which the Coq3 polypeptide is rendered unstable. (C) 2000 Elsevier Science B.V. All rights reserved.