Hydrogen sulfide: A novel component in Arabidopsis peroxisomes which triggers catalase inhibition

Abstract

Plant peroxisomes have the capacity to generate different reactive oxygen and nitrogen species (ROS and RNS), such as H2O2, superoxide radical (O2· −), nitric oxide and peroxynitrite (ONOO-). These organelles have an active nitro-oxidative metabolism which can be exacerbated by adverse stress conditions. Hydrogen sulfide (H2S) is a new signaling gasotransmitter which can mediate the posttranslational modification (PTM) persulfidation. We used Arabidopsis thaliana transgenic seedlings expressing cyan fluorescent protein (CFP) fused to a canonical peroxisome targeting signal 1 (PTS1) to visualize peroxisomes in living cells, as well as a specific fluorescent probe which showed that peroxisomes contain H2S. H2S was also detected in chloroplasts under glyphosate-induced oxidative stress conditions. Peroxisomal enzyme activities, including catalase, photorespiratory H2O2-generating glycolate oxidase (GOX) and hydroxypyruvate reductase (HPR), were assayed in vitro with a H2S donor. In line with the persulfidation of this enzyme, catalase activity declined significantly in the presence of the H2S donor. To corroborate the inhibitory effect of H2S on catalase activity, we also assayed pure catalase from bovine liver and pepper fruit-enriched samples, in which catalase activity was inhibited. Taken together, these data provide evidence of the presence of H2S in plant peroxisomes which appears to regulate catalase activity and, consequently, the peroxisomal H2O2 metabolism.