Proteomic analysis of the oxidative stress response in Kluyveromyces lactis and effect of glutathione reductase depletion.

Yeasts are unicellular eukaryotes that provide useful models for studying the oxidative stress (OS) response. Most investigations to date have been performed on the fermentative Saccharomyces cerevisiae. The respiratory Kluyveromyces lactis is emerging as an alternative model. Our previous studies showed that glutathione reductase (Glr1) is an interesting point of difference in the OS response between the two yeasts. In the present study, using extensive proteomic analyses, the response to H(2)O(2) and its relationship to Glr1 were investigated in wild-type and glr1-deletion mutant K. lactis strains. We identified 46 proteins that showed modified expression after H(2)O(2) addition and 42 for which the change was Glr1-dependent. As expected, these proteins include a variety of antioxidant enzymes, chaperones, and oxidoreductases related to defense against OS and damage repair. They also include a number of proteins necessary for energy production and carbohydrate and amino acid metabolism. H(2)O(2) addition causes down-regulation of enzymes from the glycolytic pathway and Krebs cycle in wild-type K. lactis, whereas glr1-deletion prevents this effect and actually causes up-regulation of the glycolytic, Krebs cycle, and oxidative pentose phosphate pathways. To our knowledge, this is the first global proteomic analysis performed on K. lactis.