Oxidative protein damage causes chromium toxicity in yeast

• Published in: Microbiology (Society for General Microbiology) 2005-06, Vol.151 (6), p.1939-1948
• Main Authors: Sumner, Edward R, Shanmuganathan, Anupama, Sideri, Theodora C, Willetts, Sylvia A, Houghton, John E, Avery, Simon V
• Format: Article
• Language: English
• Subjects: Aerobiosis; Anaerobiosis; Biological and medical sciences; Chromium - toxicity; DNA Glycosylases - genetics; DNA Repair - genetics; DNA-Directed DNA Polymerase - genetics; Fundamental and applied biological sciences. Psychology; Gene Deletion; Glutathione Peroxidase - genetics; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; Methionine Sulfoxide Reductases; Microbiology; Mycology; Oxidation-Reduction; Oxidoreductases - genetics; Phospholipids - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Superoxide Dismutase - analysis; Superoxide Dismutase - genetics; Superoxide Dismutase-1
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/mic.0.27945-0

1 School of Biology, Institute of Genetics, University of Nottingham, University Park, Nottingham NG7 2RD, UK 2 Department of Biology, Georgia State University, University Plaza, Atlanta, GA 30303, USA Correspondence Simon V. Avery Simon.Avery{at}nottingham.ac.uk Oxidative damage in microbial cells occurs during exposure to the toxic metal chromium, but it is not certain whether such oxidation accounts for the toxicity of Cr. Here, a Saccharomyces cerevisiae sod1 mutant (defective for the Cu,Zn-superoxide dismutase) was found to be hypersensitive to Cr(VI) toxicity under aerobic conditions, but this phenotype was suppressed under anaerobic conditions. Studies with cells expressing a Sod1p variant (Sod1 H46C ) showed that the superoxide dismutase activity rather than the metal-binding function of Sod1p was required for Cr resistance. To help identify the macromolecular target(s) of Cr-dependent oxidative damage, cells deficient for the reduction of phospholipid hydroperoxides ( gpx3 and gpx1 / gpx2 / gpx3 ) and for the repair of DNA oxidation ( ogg1 and rad30 / ogg1 ) were tested, but were found not to be Cr-sensitive. In contrast, S. cerevisiae msra ( mxr1 ) and msrb ( ycl033c ) mutants defective for peptide methionine sulfoxide reductase (MSR) activity exhibited a Cr sensitivity phenotype, and cells overexpressing these enzymes were Cr-resistant. Overexpression of MSRs also suppressed the Cr sensitivity of sod1 cells. The inference that protein oxidation is a primary mechanism of Cr toxicity was corroborated by an observed 20-fold increase in the cellular levels of protein carbonyls within 30 min of Cr exposure. Carbonylation was not distributed evenly among the expressed proteins of the cells; certain glycolytic enzymes and heat-shock proteins were specifically targeted by Cr-dependent oxidative damage. This study establishes an oxidative mode of Cr toxicity in S. cerevisiae , which primarily involves oxidative damage to cellular proteins. Abbreviations: ROS, reactive oxygen species