Protein Denitrosylation in Plant Biology

Nitric oxide (NO) is a key signalling molecule involved in fundamental processes in animals and plants. NO mainly transmits its action through post-translational modifications (NO-PTMs), among which S-nitrosylation, the covalent attachment of a NO group to a rare, highly reactive cysteine (Cys) thiol to form an S-nitrosothiol (SNO) is preeminent. In the last decade, the numbers of proteins identified that undergo S-nitrosylation has significantly increased. This analysis has revealed that a wide range of both physiological and stress response processes are regulated by this post-translational modification. To function effectively as a molecular cue, Snitrosylation must be specific and reversible. Denitrosylation, the removal of an NO group from an SNO has emerged as a key regulatory process. While the role of S-nitrosylation in plant biology has garnered significant attention, denitrosylation, a pivotal counterpoint, remains relatively unexplored. In plants, S-nitrosoglutathione reductase (GSNOR) and thioredoxin reductase (Trx)-mediated denitrosylation have emerged as key mechanisms for denitrosylation. This chapter describes the current state-of-the-art with respect to the role of denitrosylation in plant biology.