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Brazilian Journal of Microbiology

versão impressa ISSN 1517-8382versão On-line ISSN 1678-4405

Resumo

MARTINS, Vanessa; MANFREDINI, Vanusa  e  BENFATO, Mara Silveira. High levels of catalase in sod mutants of Saccharomyces cerevisiae in high aeration conditions. Braz. J. Microbiol. [online]. 2005, vol.36, n.4, pp.347-351. ISSN 1517-8382.  http://dx.doi.org/10.1590/S1517-83822005000400008.

Saccharomyces cerevisiae mutants deficient in superoxide dismutase genes (sod1D, sod2D and sod1Dsod2D mutants) in a stationary phase of growth under high aeration conditions were subjected to H2O2 stress. All the mutants were sensitive after H2O2 treatment. Glutathione peroxidase levels were significantly lower in sod1D and sod2D single mutants than in the wild-type without treatment. After exposure to H2O2 concentrations, glutathione peroxidase levels were increased in sod1Dsod2D double mutants and the sod2D single mutant, while sod1D maintained lower gluthatione peroxidase activities. The sod2D mutant demonstrated a similar catalase activity to that of the wild-type without treatment, whilst decreased catalase activity was observed in conditions of low aeration. Untreated sod1Dsod2D double mutant cells presented a lower catalase activity. Catalase levels were higher under high aeration conditions than under microaerophilic conditions, including in sod1Dsod2D cells that contain less H2O2, since SOD catalyzes the cleavage of superoxide producing H2O2 and oxygen. We suggest that catalase is not essential for sod mutants under normal conditions, but plays an important role in the acquisition of tolerance to oxidative stress induced by high aeration

Palavras-chave : catalase; superoxide dismutase; high aeration; hydrogen peroxide; S. cerevisiae.

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