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The effect of superoxide dismutase deficiency on cadmium stress
Author(s) -
Adamis Paula D. B.,
Gomes Débora Silva,
Pereira Marcos Dias,
de Mesquita Joelma Freire,
Pinto Maria Lucia Couto C.,
Panek Anita D.,
Eleutherio Elis C. A.
Publication year - 2004
Publication title -
journal of biochemical and molecular toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.526
H-Index - 58
eISSN - 1099-0461
pISSN - 1095-6670
DOI - 10.1002/jbt.20000
Subject(s) - metallothionein , cadmium , glutathione , superoxide dismutase , chemistry , sod2 , biochemistry , sod1 , cytosol , oxidative stress , enzyme , organic chemistry
Saccharomyces cerevisiae mutant strains deficient in superoxide dismutase (Sod), an antioxidant enzyme, were used to analyze cadmium absorption and the oxidation produced by it. Cells lacking the cytosolic Sod1 removed twice as much cadmium as the control strain, while those deficient in the mitochondrial Sod2 exhibited poor metal absorption. Interestingly, the sod1 mutant did not become more oxidized after exposure to cadmium, as opposed to the control strain. We observed that the deficiency of Sod1 increases the expression of both Cup1 (a metallothionein) and Ycf1 (a vacuolar glutathione S‐conjugate pump), proteins involved with protection against cadmium. Furthermore, when sod1 cells were exposed to cadmium, the ratio glutathione oxidized/glutathione reduced did not increase as expected. We propose that a high level of metallothionein expression would relieve glutathione under cadmium stress, while an increased level of Ycf1 expression would favor compartmentalization of this metal into the vacuole. Both conditions would reduce the level of glutathione‐cadmium complex in cytosol, contributing to the high capacity of absorbing cadmium by the sod1 strain. Previous results showed that the glutathione‐cadmium complex regulates cadmium uptake. These results indicate that, even indirectly, metallothionein also regulates cadmium transport. © 2004 Wiley Periodicals, Inc. J Biochem Mol Toxicol 18:12–17, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20000