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 HO, superoxide radical (O), nitric oxide and peroxynitrite (ONOO). These organelles have an active nitro-oxidative metabolism which can be exacerbated by adverse stress conditions. Hydrogen sulfide (HS) 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 HS. HS was also detected in chloroplasts under glyphosate-induced oxidative stress conditions. Peroxisomal enzyme activities, including catalase, photorespiratory HO-generating glycolate oxidase (GOX) and hydroxypyruvate reductase (HPR), were assayed in vitro with a HS donor. In line with the persulfidation of this enzyme, catalase activity declined significantly in the presence of the HS donor. To corroborate the inhibitory effect of HS 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 HS in plant peroxisomes which appears to regulate catalase activity and, consequently, the peroxisomal HO metabolism.