Oxidative protein damage causes chromium toxicity in yeast.
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.
Sumner
Edward R
ER
School of Biology, Institute of Genetics, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Shanmuganathan
Anupama
A
Department of Biology, Georgia State University, University Plaza, Atlanta, GA 30303, USA.
Sideri
Theodora C
TC
School of Biology, Institute of Genetics, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Willetts
Sylvia A
SA
School of Biology, Institute of Genetics, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Houghton
John E
JE
Department of Biology, Georgia State University, University Plaza, Atlanta, GA 30303, USA.
Avery
Simon V
SV
School of Biology, Institute of Genetics, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
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
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