Vacuolar compartmentation of the cadmium-glutathione complex protects Saccharomyces cerevisiae from mutagenesis.
In the yeast Saccharomyces cerevisiae, gamma-glutamyl transferase (gamma-GT; EC 2.3.2.2) is a vacuolar-membrane bound enzyme. In this work we verified that S. cerevisiae cells deficient in gamma-GT absorbed almost 2.5-fold as much cadmium as the wild-type (wt) cells, suggesting that this enzyme might be responsible for the recycle of cadmium-glutathione complex stored in the vacuole. The mutant strain showed difficulty in keeping constant levels of glutathione (GSH) during the stress, although the GSH-reductase activity was practically the same in both wt and mutant strains, before and after metal stress. This difficulty to maintain the GSH levels in the gamma-GT mutant strain led to high levels of lipid peroxidation and carbonyl proteins in response to cadmium, higher than in the wt, but lower than in a mutant deficient in GSH synthesis. Although the increased levels of oxidative stress, gamma-GT mutant strain showed to be tolerant to cadmium and showed similar mutation rates to the wt, indicating that the compartmentation of the GSH-cadmium complex in vacuole protects cells against the mutagenic action of the metal. Confirming this hypothesis, a mutant strain deficient in Ycf1, which present high concentrations of GSH-cadmium in cytoplasm due to its deficiency in transport the complex to vacuole, showed increased mutation rates.
Adamis
Paula D B
PD
Departamento de Bioquímica, I.Q., UFRJ, 21949-900 Rio de Janeiro, RJ, Brazil.
Panek
Anita D
AD
Eleutherio
Elis C A
EC
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D019187:Cadmium Compounds / Q000378:metabolism / Q000633:toxicity*; D002470:Cell Survival / Q000187:drug effects; D015966:Gene Expression Regulation, Fungal; D005978:Glutathione / Q000378:metabolism*; D005980:Glutathione Reductase / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D009153:Mutagens / Q000378:metabolism / Q000633:toxicity*; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects; D050050:Protein Carbonylation / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism / Q000633:toxicity*; D014617:Vacuoles / Q000201:enzymology / Q000378:metabolism*; D005723:gamma-Glutamyltransferase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D019187:Cadmium Compounds; D009153:Mutagens; D029701:Saccharomyces cerevisiae Proteins; D013431:Sulfates; C089179:YCF1 protein, S cerevisiae; C037123:cadmium sulfate; D005980:Glutathione Reductase; D005723:gamma-Glutamyltransferase; D005978:Glutathione