GSNOR-mediated de-nitrosylation in the plant defence response

A key feature of the plant defence response is the transient engagement of a nitrosative burst, resulting in the synthesis of reactive nitrogen intermediates (RNIs). Specific, highly reactive cysteine (Cys) residues of low pKa are a major site of action for these intermediates. The addition of an NO moiety to a Cys thiol to form an S-nitrosothiol (SNO), is termed S-nitrosylation. This redox-based post-translational modification is emerging as a key regulator of protein function in plant immunity. Here we highlight recent advances in our understanding of de-nitrosylation, the mechanism that depletes protein SNOs, with a focus on S-nitrosoglutathione reductase (GSNOR). This enzyme controls total cellular S-nitrosylation indirectly during the defence response by turning over S-nitrosoglutathione (GSNO), a major cache of NO bioactivity.

► S-nitrosylation has emerged as a key post-translational modification integral.
► The presence of mechanisms to switch-off signal transmission is fundamental.
► The process of de-nitrosylation is an important regulatory feature of NO bioactivity.
► GSNOR has emerged as an important player in plant de-nitrosylation.