S-Nitrosoglutathione Reductase: A Key Regulator of S-Nitrosylation in Plant Development and Stress Responses

Abstract

S-Nitrosylation has emerged recently as a new type of ubiquitous protein posttranslational modification, based on the attachment of nitroso group to cysteine thiols. S-Nitrosothiols represent relatively stable and mobile reservoir of nitric oxide bioactivity and are viewed as a convergence of signalling pathways of reactive nitrogen (RNS) and oxygen (ROS) species. This review summarises actual knowledge on S-nitrosoglutathione reductase (GSNOR), considered a key enzyme of the regulation of intracellular levels of S-nitrosoglutathione and indirectly also of protein S-nitrosothiols. The biological functions of GSNOR are mediated by its capacity to catalyse irreversible GSNO decomposition to oxidised glutathione as a part of nitric oxide catabolism. GSNOR is required for to maintain balanced levels of ROS and RNS and participate in the overall control of cell redox state. Altered expression and levels of GSNOR have been found associated with important pathological processes in animals. GSNOR is also involved in normal plant development via NO-dependent signalling mechanisms and inplant defence responses to multiple abiotic and biotic stress conditions. Despite recent considerable advances in plant S-nitrosothiol research, our understanding of signalling pathways and GSNOR-mediated catabolism of GSNO in plants is still limited. Current research focus involves studies of the molecular mechanism of GSNOR on transcriptional and post-translational level and the role of GSNOR in plant responses to stress conditions.