Functions and Metabolism of S-Nitrosothiols and S-Nitrosylation of Proteins in Plants: The Role of GSNOR

Abstract

S-nitrosylation, based on the attachment of nitroso group to cysteine thiols, is emerging as a new type of ubiquitous protein post-translational modification within the complex network of nitric oxide bioactivity. S-nitrosothiols are considered to form a relatively stable and mobile reservoir of NO bioactivity, as a convergence of signalling pathways of reactive nitrogen and oxygen species. S-nitrosylation of proteins impact their functionality, stability and cellular localization in cells. In this review, actual knowledge on protein S-nitrosylation, its function and importance in plants is presented, together with a brief survey of methods, which are actually used for S-nitrosothiol studies in plant models. S-nitrosoglutathione reductase is considered a key enzyme of the regulation of intracellular levels of S-nitrosoglutathione and indirectly also of protein S-nitrosothiols. It has a crucial role in the maintenance of balanced levels of reactive nitrogen species and participates in the control of cellular redox state. The regulation of important plant proteins, which are involved in the transduction of plant hormone signals, regulation of enzyme activities, induction of apoptosis and control of carbohydrate metabolism, by a reversible S-nitrosylation is described in more detail. Recent research in multiple plant systems has been focused to the identification of endogenously S-nitrosylated proteins in unstressed plants and S-nitrosylation patterns in plants exposed to different stress stimuli. Comparative analysis of the plant S-nitrosoproteome under control and stress conditions represents a valuable tool to obtain more insights to the role of NO in the signalling pathways of plant development and stress responses.