Vacuolar compartmentation of the cadmium-glutathione complex protects Saccharomyces cerevisiae from mutagenesis

Author(s)

Adamis, Paula D. B. ; Panek, Anita D. ; Eleutherio, Elis C. A.

• Document type: Journal article
• Source: Toxicology Letters; v. 173, n. 1, p. 1-7, Aug. 2007.
• Field of knowledge: Biological Sciences - Biochemistry

Abstract

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. (AU)

• FAPESP's process: 04/10067-6 - Stress, transport and metabolism of alpha-glycosides in Saccharomyces cerevisiae
• Grantee: Pedro Soares de Araujo
• Support Opportunities: Research Projects - Thematic Grants