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eng
Author
Miki Risa Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan
Saiki, Ryoichi Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan
Ozoe, Yoshihisa Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan
Description
Among the steps in ubiquinone biosynthesis, that catalyzed by the product of the clk‐1/coq7 gene has received considerable attention because of its relevance to life span in Caenorhabditis elegans. We analyzed the coq7 ortholog (denoted coq7) in Schizosaccharomyces pombe, to determine whether coq7 has specific roles that differ from those of other coq genes. We first confirmed that coq7 is necessary for the penultimate step in ubiquinone biosynthesis, from the observation that the deletion mutant accumulated the ubiquinone precursor demethoxyubiquinone‐10 instead of ubiquinone‐10. The coq7 mutant displayed phenotypes characteristic of other ubiquinone‐deficient Sc. pombe mutants, namely, hypersensitivity to hydrogen peroxide, a requirement for antioxidants for growth on minimal medium, and an elevated production of sulfide. To compare these phenotypes with those of other respiration‐deficient mutants, we constructed cytochrome c (cyc1) and coq3 deletion mutants. We also assessed accumulation of oxidative stress in various ubiquinone‐deficient strains and in the cyc1 mutant by measuring mRNA levels of stress‐inducible genes and the phosphorylation level of the Spc1 MAP kinase. Induction of ctt1, encoding catalase, and apt1, encoding a 25 kDa protein, but not that of gpx1, encoding glutathione peroxidase, was indistinguishable in four ubiquinone‐deficient mutants, indicating that the oxidative stress response operates at similar levels in the tested strains. One new phenotype was observed, namely, loss of viability in stationary phase (chronological life span) in both the ubiquinone‐deficient mutant and in the cyc1 mutant. Finally, Coq7 was found to localize in mitochondria, consistent with the possibility that ubiquinone biosynthesis occurs in mitochondria in yeasts. In summary, our results indicate that coq7 is required for ubiquinone biosynthesis and the coq7 mutant is not distinguishable from other ubiquinone‐deficient mutants, except that its phenotypes are more pronounced than those of the cyc1 mutant.
Journal Title
The FEBS Journal
Volume
275
Issue
21
Start Page
5309
End Page
5324
ISSN
1742-464X
ISSN(Online)
1742-4658
Published Date
2008-10-13
DOI
Publisher
Federation of European Biochemical Societies
NII Type
Journal Article
Format
PDF
Text Version
著者版
OAI-PMH Set
Faculty of Life and Environmental Science
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