Investigation of protein expression of Saccharomyces cerevisiae cells in quiescent and proliferating state before and after toxic stress

The focus of the present study is to determine proteins responsible for the oxidative and toxic stress response in proliferating and stationary phase (G(0)) cultures. Therefore, the yeast Saccharomyces cerevisiae was treated with oxidative and drug compounds (H2O2, menadione, zeocin, and ibuprofen) in both phases. These substances were chosen to determine the redox status of the yeast. S. cerevisiae appeared to employ different strategies to ensure their antioxidant defence metabolism. Analysis, including sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) coupled with mass spectrometry, was used in the search. The proteins were identified by SDS-PAGE, matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry analysis, and Mascot database-fingerprint. The final step was determination of protein profiles of yeast S. cerevisiae in proliferating (M) and stationary phase (G(0)). Seven bands were determined and the corresponding proteins were proposed: cytochrome c peroxidase, glutathione S-transferase omega-like, NAPDH-dependent diflavin reductase, DNA replication fork-blocking protein, putative aryl alcohol dehydrogenase, AP-1-like transcription factor YAP5, GTP-binding protein. All putative proteins coincide with the literature database. A typical example of such an adaptation mechanism in the defence against oxidative damage is the synthesis of several glutathione and thioredoxin peroxidases in the yeast cell. A deeper investigation of the conserved mechanisms responsible for entry into, survival, and exit from quiescence in higher eukaryotes will help the development of new anticancer therapies, the study in the process of ageing and neurodegenerative diseases.