title: Oxidative protein damage causes chromium toxicity in yeast.
abstract: 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 sod1Delta 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 (gpx3Delta and gpx1Delta/gpx2Delta/gpx3Delta) and for the repair of DNA oxidation (ogg1Delta and rad30Delta/ogg1Delta) were tested, but were found not to be Cr-sensitive. In contrast, S. cerevisiae msraDelta (mxr1Delta) and msrbDelta (ycl033cDelta) 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 sod1Delta cells. The inference that protein oxidation is a primary mechanism of Cr toxicity was corroborated by an observed approximately 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.
authors.affiliation: School of Biology, Institute of Genetics, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Edward R
authors.initials: ER
authors.lastname: Sumner
authors.affiliation: Department of Biology, Georgia State University, University Plaza, Atlanta, GA 30303, USA.
authors.forename: Anupama
authors.initials: A
authors.lastname: Shanmuganathan
authors.affiliation: School of Biology, Institute of Genetics, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Theodora C
authors.initials: TC
authors.lastname: Sideri
authors.affiliation: School of Biology, Institute of Genetics, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Sylvia A
authors.initials: SA
authors.lastname: Willetts
authors.affiliation: Department of Biology, Georgia State University, University Plaza, Atlanta, GA 30303, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Houghton
authors.affiliation: School of Biology, Institute of Genetics, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Simon V
authors.initials: SV
authors.lastname: Avery
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D002857:Chromium / Q000633:toxicity*; D045647:DNA Glycosylases / Q000235:genetics; D004260:DNA Repair / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D017353:Gene Deletion; D005979:Glutathione Peroxidase / Q000235:genetics; D051150:Methionine Sulfoxide Reductases; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics; D010743:Phospholipids / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000032:analysis / Q000235:genetics; D000072105:Superoxide Dismutase-1; D000099270:Y-Family DNA Polymerases
chemical_list: D002857:Chromium; D045647:DNA Glycosylases; D004259:DNA-Directed DNA Polymerase; D005979:Glutathione Peroxidase; D051150:Methionine Sulfoxide Reductases; D010088:Oxidoreductases; D010743:Phospholipids; D029701:Saccharomyces cerevisiae Proteins; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; C074702:chromium hexavalent ion; C492173:GPX2 protein, S cerevisiae; C494438:HYR1 protein, S cerevisiae; C027219:methionine sulfoxide reductase; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases