Protective role of superoxide dismutases against ionizing radiation in yeast

• Published in: Biochimica et biophysica acta 2001-05, Vol.1526 (2), p.191-198
• Main Authors: Lee, Jin Hyup, Choi, In Youl, Kil, In Sup, Kim, Sun Yee, Yang, Eun Sun, Park, Jeen-Woo
• Format: Article
• Language: English
• Subjects: Antioxidant enzyme; Catalase - metabolism; Catalase - radiation effects; Cell-Free System; Enzyme Activation - radiation effects; Glucosephosphate Dehydrogenase - metabolism; Glucosephosphate Dehydrogenase - radiation effects; Glutathione Reductase - metabolism; Glutathione Reductase - radiation effects; Ionizing radiation; Mutant strain; Oxidation-Reduction; Reactive oxygen species; Reactive Oxygen Species - metabolism; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - radiation effects; Superoxide dismutase; Superoxide Dismutase - genetics; Superoxide Dismutase - metabolism; Superoxide Dismutase - radiation effects; Thiobarbituric Acid Reactive Substances - analysis
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/S0304-4165(01)00126-X

The protective role of superoxide dismutases (SODs) against ionizing radiation, which generates reactive oxygen species (ROS) harmful to cellular function, was investigated in the wild-type and in mutant yeast strains lacking cytosolic CuZnSOD (sod1Δ), mitochondrial MnSOD (sod2Δ), or both SODs (sod1Δsod2Δ). Upon exposure to ionizing radiation, there was a distinct difference between these strains in regard to viability and the level of protein carbonyl content, which is the indicative marker of oxidative damage to protein, intracellular H2O2 level, as well as lipid peroxidation. When the oxidation of 2′,7′-dichlorofluorescin was used to examine the hydroperoxide production in yeast cells, the SOD mutants showed a higher degree of increase in fluorescence upon exposure to ionizing radiation as compared to wild-type cells. These results indicated that mutants deleted for SOD genes were more sensitive to ionizing radiation than isogenic wild-type cells. Induction and inactivation of other antioxidant enzymes, such as catalase, glucose 6-phosphate dehydrogenase, and glutathione reductase, were observed after their exposure to ionizing radiation both in wild-type and in mutant cells. However, wild-type cells maintained significantly higher activities of antioxidant enzymes than did mutant cells. These results suggest that both CuZnSOD and MnSOD may play a central role in protecting cells against ionizing radiation through the removal of ROS, as well as in the protection of antioxidant enzymes.