Abstract
S-nitroso-l-cysteine (L-CSNO) behaves as a ligand. Its soluble guanylate cyclase–independent (sGC-independent) effects are stereoselective — that is, not recapitulated by S-nitroso-d-cysteine (D-CSNO) — and are inhibited by chemical congeners. However, candidate L-CSNO receptors have not been identified. Here, we have used 2 complementary affinity chromatography assays — followed by unbiased proteomic analysis — to identify voltage-gated K+ channel (Kv) proteins as binding partners for L-CSNO. Stereoselective L-CSNO–Kv interaction was confirmed structurally and functionally using surface plasmon resonance spectroscopy; hydrogen deuterium exchange; and, in Kv1.1/Kv1.2/Kvβ2-overexpressing cells, patch clamp assays. Remarkably, these sGC-independent L-CSNO effects did not involve S-nitrosylation of Kv proteins. In isolated rat and mouse respiratory control (petrosyl) ganglia, L-CSNO stereoselectively inhibited Kv channel function. Genetic ablation of Kv1.1 prevented this effect. In intact animals, L-CSNO injection at the level of the carotid body dramatically and stereoselectively increased minute ventilation while having no effect on blood pressure; this effect was inhibited by the L-CSNO congener S-methyl-l-cysteine. Kv proteins are physiologically relevant targets of endogenous L-CSNO. This may be a signaling pathway of broad relevance.
Highlights
S-nitroso-l-cysteine (L-CSNO) is a labile small molecule with bioactivities distinct from those of either l-cysteine or NO
Bands fluorescing in the absence of L-CSMe/L-CSφ were compared with control (Figure 1A) by liquid chromatography–mass spectrometry (LC-MS)
Using an unbiased proteomic approach and several validation steps, we have identified a class of cell membrane–associated proteins that are structurally and functionally modified by L-CSNO
Summary
S-nitroso-l-cysteine (L-CSNO) is a labile small molecule with bioactivities distinct from those of either l-cysteine or NO. It can be produced in mammals by breakdown of S-nitroso-glutathione (GSNO) [1, 2], which is formed by NO synthases [2,3,4,5], hemoglobin (Hb) [1, 6,7,8] and other metalloproteins [2, 9]. Stereoselective, ligand-like neuronal, endothelial, muscular, and immune effects have been described for endogenous L-CSNO [12,13,14,15,16,17,18,19]. We performed an unbiased proteomic analysis of the L-CSNO interactome to identify candidate binding partners that could underlie its ligand-like behavior
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
