Lap4, a vacuolar aminopeptidase I, is involved in cadmium-glutathione metabolism |
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Authors: | Paula D B Adamis Sergio C Mannarino Cristiano J Riger Giselle Duarte Ana Cruz Marcos D Pereira Elis C A Eleutherio |
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Institution: | (1) Departmento de Bioquímica, IQ, UFRJ, 21941-909 Rio de Janeiro, RJ, Brazil |
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Abstract: | In Saccharomyces cerevisiae, accumulation of cadmium-glutathione complex in cytoplasm inhibits cadmium absorption, glutathione transferase 2 is required
for the formation of the complex and the vacuolar gamma-glutamyl transferase participates of the first step of glutathione
degradation. Here, we proposed that Lap4, a vacuolar amino peptidase, is involved in glutathione catabolism under cadmium
stress. Saccharomyces cerevisiae cells deficient in Lap4 absorbed almost 3-fold as much cadmium as the wild-type strain (wt), probably due to the lower rate
of cadmium-glutathione complex synthesis in the cytoplasm. In wt, but not in lap4 strain, the oxidized/reduced GSH ratio and the Gtt activity increased in response to cadmium, confirming that the mutant
is deficient in the synthesis of the complex probably because the degradation of vacuolar glutathione is impaired. Thus, under
cadmium stress, Lap4 and gamma-glutamyl transferase seem to work together to assure an efficient glutathione turnover stored
in the vacuole. |
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Keywords: | Lap4 Cadmium Glutathione Mutagenesis Saccharomyces cerevisiae |
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