SUBUNIT-II OF YEAST QH2 - CYTOCHROME-C OXIDOREDUCTASE - NUCLEOTIDE-SEQUENCE OF THE GENE AND FEATURES OF THE PROTEIN
SUBUNIT-II OF YEAST QH2 - CYTOCHROME-C OXIDOREDUCTASE - NUCLEOTIDE-SEQUENCE OF THE GENE AND FEATURES OF THE PROTEIN
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DOI：
10.1111/j.1432-1033.1987.tb10741.x
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发表时间：
1987-02-16
期刊：
影响因子：
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通讯作者：
GRIVELL, LA
中科院分区：
文献类型：
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作者：
OUDSHOORN, P;VANSTEEG, H;GRIVELL, LA
一个2.5倍的核苷酸序列。酵母细胞核DNA的103碱基片段已被测定，该片段含有泛喹酚：细胞色素-c氧化还原酶40 kDa亚基II的结构基因。该区域只有一个阅读框，长度足以编码一个亚基II大小的蛋白质。预测的成熟蛋白质长度为352个氨基酸，相对分子质量为38714 Da。它主要是亲水性的，总的极性为45%。将该阅读框序列与40 kDa成熟蛋白N端直接测序的结果进行比较，发现亚基II是作为较长的前体合成的，其延伸部分为N-末端。前序列长16个氨基酸，含有大量带正电荷的残基，缺少酸性残基。它还含有丰富的中性、极性氨基酸。DNA的S1核酸酶保护分析。RNA杂交鉴定了该基因的两个主要转录本和一个次要转录本，其5‘’末端位于起始密码子上游约55、65和75个核苷酸。这些末端的5‘’序列与其他进口线粒体蛋白的调控序列缺乏明显的同源性，后者的合成受氧和分解代谢抑制的控制。通过一步基因破坏程序构建了一个缺失功能亚基II基因的突变体。该突变体在甘油上生长缓慢，并且仍然表现出低水平的Qh2：细胞色素-c氧化还原酶活性(约。野生型的5%)。讨论了这一发现对亚基II在复合体中的可能作用的影响。
The nucleotide sequence of a 2.5 .times. 103-base segment of yeast nuclear DNA, containing the structural gene for the 40-kDa subunit II of the ubiquinol:cytochrome-c oxidoreductase, has been determined. The region contains only one single reading frame of length sufficient to encode a protein of the size of subunit II. The mature protein is predicted to have a length of 352 amino acids, with a molecular mass of 38714 Da. It is predominantly hydrophilic, with an overall polarity of 45%. Comparison of the sequence of the reading frame with that derived from direct sequence analysis of the N terminus of the mature 40-kDa protein shows that subunit II is synthesized as a longer precursor and shows that the extension is N-terminal. The presequence is 16 amino acids long and it contains a number of positively charged residues and lacks acidic ones. It is also rich in neutral, polar amino acids. S1 nuclease protection analysis of DNA .cntdot. RNA hybrids identifies two major and one minor transcript of the gene, whose 5'' termini map approximately 55, 65 and 75 nucleotides upstream of the initiation codon. Sequences 5'' of these termini lack obvious homology to the regulatory sequences of other imported mitochondrial proteins, whose synthesis is controlled by oxygen and by catabolite repression. A mutant lacking a functional subunit II gene has been constructed by a one-step gene-disruption procedure. This mutant grows only slowly on glycerol and still displays a low level of QH2: cytochrome-c oxidoreductuase activity (approx. 5% of that of wild type). The implications of this finding for the possible role of subunit II in the complex are discussed.