Distinct Redox Regulation in Sub-Cellular Compartments in Response to Various Stress Conditions in Saccharomyces cerevisiae

Anita Ayer,Gabriel G Perrone,Julia Sanwald,Andreas J Meyer,Bethany A Pillay,Ian W Dawes,Julian Rutherford

doi:10.1371/journal.pone.0065240

Anita Ayer, Gabriel G Perrone + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0065240

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Journal: PloS one	Publication Date: Jun 7, 2013
Citations: 88	License type: CC BY 4.0

Affiliation: UNSW Sydney, Western Sydney University, University of Bonn

Abstract

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.

Highlights

Eukaryotic organisms have evolved to maintain distinct redox environments in organelles, allowing compartmental specific processes to occur
The advent of genetically encoded fluorescent probes such as roGFP2 and pHluorin has allowed compartmental redox dynamics to be studied in an in-depth manner for the first time
By using roGFP2 and pHluorin localized to the cytosol, mitochondrial matrix and peroxisome, a better understanding can be gained of the precise nature of sub-cellular redox homeostasis during changing cellular settings especially during stress conditions

Summary

Introduction

Eukaryotic organisms have evolved to maintain distinct redox environments in organelles, allowing compartmental specific processes to occur. The endoplasmic reticulum and mitochondrial intermembrane space have been observed to maintain a more oxidizing environment [1,2]. Aberrant sub-cellular redox environments can be detrimental, affecting a broad range of cellular processes including signal transduction, RNA, DNA and protein synthesis [3,4,5] and cell cycle regulation [6,7]. Redox dysfunction has been implicated in various stress conditions including osmotic, heat and oxidative stress through protein and microarray data, and resistance/sensitivity phenotypes [9,10,11,12,13]. The exact change to sub-cellular redox state under various stress conditions is unknown

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