Characterization of Saccharomyces cerevisiae ubiquinone‐deficient mutants

Article type: Research Article

Authors: Schultz, Jeffery R.^; | Clarke, Catherine F.^;

Affiliations: Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, CA 90095‐1569, USA | Department of Chemistry, Pacific Lutheran University, Tacoma, WA 98447‐0003, USA

Note: [] Correspondence: Catherine F. Clarke, UCLA, Department of Chemistry and Biochemistry, 607 Circle Drive South, Los Angeles, CA 90095‐1569, USA. Tel.: +1 310 825 0771; Fax: +1 310 206 5213; E‐mail: cathy@ ewald.mbi.ucla.edu.

Abstract: Ubiquinol (QH_{2}) is a lipid‐soluble molecule that participates in cellular redox reactions. Previous studies have shown that yeast mutants lacking QH_{2} are hypersensitive to treatment with polyunsaturated fatty acids (PUFAs) indicating that QH_{2} can function as an antioxidant in vivo. In this study the effect of 1 mM linolenic acid on levels of Q_{6} and Q_{6}H_{2} is assessed in both wild‐type and respiration‐deficient (atp2\Delta) strains. The response of Q‐deficient mutants to other forms of oxidative stress is further characterized to define those conditions where QH_{2} acts as an antioxidant. Endogenous antioxidant defense systems were also assessed in wild‐type, Q‐deficient, and atp2\Delta strains. Superoxide dismutase (SOD) activity decreased and catalase activity increased in both Q‐deficient and atp2\Delta mutants compared to wild‐type cells, suggesting that such changes result from the loss of respiration rather than the lack of Q.

Journal: Biofactors, vol. 9, no. 2-4, pp. 121-129, 1999