Endogenous NO fluctuations in Arabidopsis leaves influence peroxisomal activities and ROS, NADPH, and H2S metabolism.

Abstract

Nitric oxide (NO) is a gasotransmitter that exerts signaling functions in plants. Using 30-day-old Arabidopsis thaliana plants wild type and transgenic lines with different NO content (Atnoa1 and Atnox1/cue1), the biochemical analysis of key components in the metabolism of ROS, NADPH, NO, and H₂S in leaves indicates that the imbalance of endogenous cellular NO triggered differential changes in many of the analyzed biochemical parameters including the protein profile of S-glutathionylation, S-nitrosation, tyrosine and tryptophan nitration. It was remarkable the differences observed in the antioxidant enzyme catalase and the H₂O₂-generating glycolate oxidase, two key peroxisomal enzymes involved in the ROS metabolism of these organelles, as well as the gene expression of the polyamine oxidase 4 (POD4) which encodes for the peroxisomal H₂O₂-generating POD4. Furthermore, the pattern of the H₂S-generating L-cysteine desulfhydrase (LCD) isozymatic activity was also affected. These data provide new biochemical evidence of how under physiological conditions, NO can affect peroxisomal metabolism, a subcellular organelle with a very active nitro-oxidative metabolism, as well as ROS, NADPH, and H₂S metabolism.