Target-Selective Protein S-Nitrosylation by Sequence Motif Recognition

S-nitrosylation is a ubiquitous protein modification emerging as a principal mechanism of nitric oxide (NO)-mediated signal transduction and cell function. S-nitrosylases can use NO synthase (NOS)-derived NO to modify selected cysteines in target proteins. Despite proteomic identification of over a thousand S-nitrosylated proteins, few S-nitrosylases have been identified. Moreover, mechanisms underlying site-selective S-nitrosylation and the potential role of specific sequence motifs remain largely unknown. Here, we describe a stimulus-inducible, heterotrimeric S-nitrosylase complex consisting of inducible NOS (iNOS), S100A8, and S100A9. S100A9 exhibits transnitrosylase activity, shuttling NO from iNOS to the target protein, whereas S100A8 and S100A9 coordinately direct site selection. A family of proteins S-nitrosylated by iNOS-S100A8/A9 were revealed by proteomic analysis. A conserved I/L-X-C-X2-D/E motif was necessary and sufficient for iNOS-S100A8/A9-mediated S-nitrosylation. These results reveal an elusive parallel between protein S-nitrosylation and phosphorylation, namely, stimulus-dependent posttranslational modification of selected targets by primary sequence motif recognition. [Display omitted] •Discovery of stimulus-inducible, iNOS-containing S-nitrosylase complex•Intracellular function of S100A8/A9 in site-selective S-nitrosylation•Proteomic analysis reveals family of iNOS-S100A8/A9 targets•Primary sequence motif directing site-selective S-nitrosylation The discovery of the primary sequence motif directing S-nitrosylation and the nitrosylase complex mediating this ubiquitous posttranslational modification that is emerging as an important pathophysiological regulator of signal transduction and cell function.