Changes in the redox state of Escherichia coli cells during phosphate starvation

Abstract

Redox regulation of cellular processes is one of the most important factors providing metabolic reprogramming when bacteria adapt to environmental changes. The aim of this work was to study changes in the redox status of glutathione in E. coli cells during phosphate starvation. We showed that the transition of E. coli from growth to phosphate starvation is accompanied by H₂S production, export of free cysteine to the medium, and an increase in the concentration of intracellular glutathione. An increase in the level of reduced glutathione (GSH) in the absence of changes in the concentration of oxidized glutathione (GSSG) led to an increase in the ratio of GSH/GSSG inside wild-type cells and all studied mutants in the components of thiol redox systems. High redox status of the cells was maintained during two days of starvation. Intensive oxidation of GSH during phosphate starvation occurred only in the simultaneous absence of glutathione reductase and thioredoxin reductase. We suggest that the observed changes in the level of thiols and H₂S are largely aimed at maintaining cysteine homeostasis and preventing oxidative stress.