14-3-3 binding and phosphorylation of neuroglobin during hypoxia modulate six-to-five heme pocket coordination and rate of nitrite reduction to nitric oxide.

摘要: Neuroglobin protects neurons from hypoxia in vitro and vivo; however, the underlying mechanisms for this effect remain poorly understood. Most of neuroglobin is present a hexacoordinate state with proximal distal histidines heme pocket directly bound to iron. At equilibrium, concentration five-coordinate remains very low (0.1–5%). Recent studies have shown that post-translational redox regulation surface thiol disulfide formation increases open probability allows nitrite binding reaction form NO. We hypothesized equilibrium between six- states secondary reactions NO could be regulated by other hypoxia-dependent modification(s). Protein sequence models identified candidate sites both 14-3-3 phosphorylation. In experiments human SH-SY5Y neuronal cells exposed glucose deprivation, we observed 1) phosphorylation protein-protein interactions increase during hypoxic metabolic stress; 2) stabilizes half-life phosphorylation; 3) pocket, which ligand (CO nitrite) accelerates rate anaerobic reduction These data reveal series modifications regulate six-to-five access ligands. Hypoxia-regulated may contribute cellular adaptation hypoxia.