NAM9 NUCLEAR SUPPRESSOR OF MITOCHONDRIAL OCHRE MUTATIONS IN SACCHAROMYCES-CEREVISIAE CODES FOR A PROTEIN HOMOLOGOUS TO S4 RIBOSOMAL-PROTEINS FROM CHLOROPLASTS, BACTERIA, AND EUKARYOTES
NAM9 NUCLEAR SUPPRESSOR OF MITOCHONDRIAL OCHRE MUTATIONS IN SACCHAROMYCES-CEREVISIAE CODES FOR A PROTEIN HOMOLOGOUS TO S4 RIBOSOMAL-PROTEINS FROM CHLOROPLASTS, BACTERIA, AND EUKARYOTES
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DOI：
10.1128/mcb.12.1.402
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发表时间：
1992-01-01
影响因子：
5.3
通讯作者：
KRUSZEWSKA, A
中科院分区：
文献类型：
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作者：
BOGUTA, M;DMOCHOWSKA, A;KRUSZEWSKA, A
我们报道了一种新的核抑制基因——来自酿酒酵母的NAM9基因的遗传特征、分子克隆和测序，该基因作用于线粒体DNA的突变。菌株NAM9-1是一种线粒体线粒体线粒体突变体的呼吸能力突变体，该突变体携带oxil基因的V25赭石突变。NAM9-1突变的遗传特征表明，它是一个核显性的全能抑制因子，减轻了所有四种线粒体基因的突变，并提示其信息特征，可能是核糖体特征。利用NAM9-1 rho0菌株的基因库，将受体oxil-V25突变体转化为呼吸能力，克隆了NAM9基因。正交场交替凝胶电泳分析和遗传定位将NAM9基因定位在XIV染色体右臂上。对NAM9基因的序列分析表明，该基因编码一个485个氨基酸的基本蛋白，其前置序列可将该蛋白靶向线粒体基质。推断出的NAM9产物的200个氨基酸的n端序列与叶绿体和细菌的S4核糖体蛋白非常相似。与包括酿酒酵母在内的低等真核生物的核糖体细胞质蛋白存在显著的相似性。NAM9+基因的染色体失活对细胞并不致命，但会导致呼吸缺陷和线粒体DNA完整性的丧失。我们得出结论，NAM9基因产物是在其他系统中发现的S4核糖体蛋白的线粒体核糖体对应物，并且抑制因子通过降低翻译的保真度而起作用。
We report the genetic characterization, molecular cloning, and sequencing of a novel nuclear suppressor, the NAM9 gene from Saccharomyces cerevisiae, which acts on mutations of mitochondrial DNA. The strain NAM9-1 was isolated as a respiration-competent revertant of a mitochondrial mit mutant which carries the V25 ochre mutation in the oxil gene. Genetic characterization of the NAM9-1 mutation has shown that it is a nuclear dominant omnipotent suppressor alleviating several mutations in all four mitochondrial genes tested and has suggested its informational, and probably ribosomal, character. The NAM9 gene was cloned by transformation of the recipient oxil-V25 mutant to respiration competence by using a gene bank from the NAM9-1 rho0 strain. Orthogonal-field alternation gel electrophoresis analysis and genetic mapping localized the NAM9 gene on the right arm of chromosome XIV. Sequence analysis of the NAM9 gene showed that it encodes a basic protein of 485 amino acids with a presequence that could target the protein to the mitochondrial matrix. The N-terminal sequence of 200 amino acids of the deduced NAM9 product strongly resembles the S4 ribosomal proteins from chloroplasts and bacteria. Significant although less extensive similarity was found with ribosomal cytoplasmic proteins from lower eucaryotes, including S. cerevisiae. Chromosomal inactivation of the NAM9+ gene is not lethal to the cell but leads to respiration deficiency and loss of mitochondrial DNA integrity. We conclude that the NAM9 gene product is a mitochondrial ribosomal counterpart of S4 ribosomal proteins found in other systems and that the suppressor acts through decreasing the fidelity of translation.