Glutathione peroxidases as redox sensor proteins in plant cells

• Published in: Plant science (Limerick) 2015-05, Vol.234, p.22-26
• Main Authors: Passaia, Gisele, Margis-Pinheiro, Márcia
• Format: Article
• Language: English
• Subjects: Glutathione - metabolism; Glutathione Peroxidase - metabolism; Glutathione peroxidases; Hydrogen Peroxide - metabolism; Oxidation-Reduction; Oxidative Stress; Peroxiredoxins - metabolism; Plant Proteins - metabolism; Reactive oxygen species; Reactive Oxygen Species - metabolism; Redox regulation; Redox signaling; Signal Transduction; Thioredoxins - metabolism
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2015.01.017

•The dual role of H2O2 as a damaging compound and as a messenger requires a tightly balanced defense system.•Redox sensor and signaling functions are being attributed to glutathione peroxidases in prokaryotes, fungi and plants.•Plant GPXs play an important role in redox signaling transduction in addition to their peroxidase activity. Glutathione peroxidases are thiol-based enzymes that catalyze the reduction of H2O2 and hydroperoxides to H2O or alcohols, they mitigate the toxicity of these compounds to the cell mainly using thioredoxin as an electron donor. Additionally, certain redox sensor and signaling functions are being ascribed to these enzymes in prokaryotes, fungi, and plants. We review the evolutionary history, enzymatic and biochemical evidence that make GPX proteins, in addition to being peroxiredoxins, important candidates for acting as redox sensor proteins in plants: (i) the lower peroxidase activity of Cys-GPX; (ii) the thiol catalytic center; (iii) the capacity to interact with regulatory proteins. All these characteristics suggest that at the basal level, plant GPXs have an important role in redox signal transduction in addition to their peroxidase activity.