Distinct redox regulation in sub-cellular compartments in response to various stress conditions in Saccharomyces cerevisiae

• Published in: PloS one Vol. 8; no. 6; p. e65240
• Main Authors: Ayer, Anita, Sanwald, Julia, Pillay, Bethany A, Meyer, Andreas J, Perrone, Gabriel G, Dawes, Ian W
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.06.2013; Public Library of Science (PLoS)
• Subjects: Adaptation, Physiological - drug effects; Amino acids; Biology; Carbon - pharmacology; Cell Compartmentation - drug effects; Cell culture; Cell cycle; Compartments; Couples; Cytosol; Cytosol - drug effects; Cytosol - metabolism; Endoplasmic reticulum; Environmental stress; Fermentation - drug effects; Fluorescence; Fluorescent indicators; Glutathione; Green Fluorescent Proteins - metabolism; Heat stress; Heat tolerance; Heat-Shock Response - drug effects; Homeostasis; Hydrogen; Hydrogen ions; Hydrogen peroxide; Hydrogen Peroxide - toxicity; Hydrogen-Ion Concentration - drug effects; Metabolism; Microscopy, Confocal; Mitochondria; Mitochondria - drug effects; Mitochondria - metabolism; Organelles; Oxidation-Reduction - drug effects; Paraquat - toxicity; Peroxisomes - drug effects; Peroxisomes - metabolism; pH effects; Physiology; Potassium - pharmacology; Proteins; Redox properties; Reproducibility of Results; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - physiology; Signal transduction; Sodium - pharmacology; Sorbitol - pharmacology; Stationary phase; Stress, Physiological - drug effects; Subcellular Fractions - drug effects; Subcellular Fractions - metabolism; Yeast
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0065240

Responses to many growth and stress conditions are assumed to act via changes to the cellular redox status. However, direct measurement of pH-adjusted redox state during growth and stress has never been carried out. Organellar redox state (E GSH) was measured using the fluorescent probes roGFP2 and pHluorin in Saccharomyces cerevisiae. In particular, we investigated changes in organellar redox state in response to various growth and stress conditions to better understand the relationship between redox-, oxidative- and environmental stress response systems. E GSH values of the cytosol, mitochondrial matrix and peroxisome were determined in exponential and stationary phase in various media. These values (-340 to -350 mV) were more reducing than previously reported. Interestingly, sub-cellular redox state remained unchanged when cells were challenged with stresses previously reported to affect redox homeostasis. Only hydrogen peroxide and heat stress significantly altered organellar redox state. Hydrogen peroxide stress altered the redox state of the glutathione disulfide/glutathione couple (GSSG, 2H(+)/2GSH) and pH. Recovery from moderate hydrogen peroxide stress was most rapid in the cytosol, followed by the mitochondrial matrix, with the peroxisome the least able to recover. Conversely, the bulk of the redox shift observed during heat stress resulted from alterations in pH and not the GSSG, 2H(+)/2GSH couple. This study presents the first direct measurement of pH-adjusted redox state in sub-cellular compartments during growth and stress conditions. Redox state is distinctly regulated in organelles and data presented challenge the notion that perturbation of redox state is central in the response to many stress conditions.