Physiological relevance of plant 2‐Cys peroxiredoxin overoxidation level and oligomerization status

Peroxiredoxins are ubiquitous thioredoxin‐dependent peroxidases presumed to display, upon environmental constraints, a chaperone function resulting from a redox‐dependent conformational switch. In this work, using biochemical and genetic approaches, we aimed to unravel the factors regulating the redox status and the conformation of the plastidial 2‐Cys peroxiredoxin (2‐Cys PRX) in plants. In Arabidopsis, we show that in optimal growth conditions, the overoxidation level mainly depends on the availability of thioredoxin‐related electron donors, but not on sulfiredoxin, the enzyme reducing the 2‐Cys PRX overoxidized form. We also observed that upon various physiological temperature, osmotic and light stress conditions, the overoxidation level and oligomerization status of 2‐Cys PRX can moderately vary depending on the constraint type. Further, no major change was noticed regarding protein conformation in water‐stressed Arabidopsis, barley and potato plants, whereas species‐dependent up‐ and down‐variations in overoxidation were observed. In contrast, both 2‐Cys PRX overoxidation and oligomerization were strongly induced during a severe oxidative stress generated by methyl viologen. From these data, revealing that the oligomerization status of plant 2‐Cys PRX does not exhibit important variation and is not tightly linked to the protein redox status upon physiologically relevant environmental constraints, the possible in planta functions of 2‐Cys PRX are discussed.