Cytosolic thioredoxin peroxidase I is essential for the antioxidant defense of yeast with dysfunctional mitochondria

The specific role of cytosolic thioredoxin peroxidase I (cTPx I), encoded by TSA1 (thiol-speciric antioxidant), was investigated in the oxidative stress response of Saccharomyces ceravisiae. In most cases, deletion of TSA1 has showed only a slight effect on hydrogen peroxide sensitivity. However, when the functional state of the mitochondria was compromised, the necessity of TSA1 in cell protection against this oxidant was much more evident. All the procedures used to disrupt the mitochondrial respiratory chain promoted increases in the generation of H2O2 in Cells, which could be related to their elevated sensitivity to oxidative stress. In. fact, TSA1 is highly expressed when cells with respiratory deficiency are exposed to H2O2. In conclusion, our results indicate that cTPx I is a key component of the antioxidant defense in respiratory-deficient cells. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.