Protective function of chloroplast 2-cysteine peroxiredoxin in photosynthesis. Evidence from transgenic Arabidopsis

2-Cysteine peroxiredoxins (2-CPs) constitute a ubiquitous group of peroxida ses that reduce cell-toxic alkyl hydroperoxides to their corresponding alco hols. Recently, we cloned 2-CP cDNAs from plants and characterized them as chloroplast proteins. To elucidate the physiological function of the 2-CP i n plant metabolism, we generated antisense mutants in Arabidopsis. In the m utant lines a 2-CP deficiency developed during early leaf and plant develop ment and eventually the protein accumulated to wild-type levels. In young m utants with reduced amounts of 2-CP, photosynthesis was impaired and the le vels of D1 protein, the light-harvesting protein complex associated with ph otosystem II, chloroplast ATP synthase, and ribulose-1,5-bisphosphate carbo xylase/oxygenase were decreased. Photoinhibition was particularly pronounce d after the application of the protein synthesis inhibitor, lincomycin. We concluded that the photosynthetic machinery needs high levels of 2-CP durin g leaf development to protect it from oxidative damage and that the damage is reduced by the accumulation of 2-CP protein, by the de novo synthesis an d replacement of damaged proteins, and by the induction of other antioxidan t defenses in 2-CP mutants.