5o27
From Proteopedia
Crystal structure of murine neuroglobin mutant V140W under 30 bar xenon pressure
Structural highlights
Function[NGB_MOUSE] Involved in oxygen transport in the brain. Hexacoordinate globin, displaying competitive binding of oxygen or the distal His residue to the iron atom. Not capable of penetrating cell membranes. The deoxygenated form exhibits nitrite reductase activity inhibiting cellular respiration via NO-binding to cytochrome c oxidase. Involved in neuroprotection during oxidative stress. May exert its anti-apoptotic activity by acting to reset the trigger level of mitochondrial cytochrome c release necessary to commit the cells to apoptosis.[1] [2] Publication Abstract from PubMedInternal cavities are crucial for conformational flexibility of proteins and can be mapped through noble gas diffusion and docking. Here we investigate the hydrophobic cavities and tunnel network in neuroglobin (Ngb), a hexacoordinated heme protein likely to be involved in neuroprotection, using crystallography under noble gas pressure, mostly at room temperature. In murine Ngb, a large internal cavity is involved in the heme sliding mechanism to achieve binding of gaseous ligands through coordination to the heme iron. In this study, we report that noble gases are hosted by two major sites within the internal cavity. We propose that these cavities could store oxygen and allow its relay in the heme proximity, which could correspond to NO location in the nitrite-reductase function of Ngb. Thanks to a recently designed pressurization cell using krypton at high pressure, a new gas binding site has been characterized that reveals an alternate pathway for gaseous ligands. A new gas binding site on the proximal side of the heme has also been characterized, using xenon pressure on a Ngb mutant (V140W) that binds CO with a similar rate and affinity to the wild-type, despite a reshaping of the internal cavity. Moreover, this study, to our knowledge, provides new insights into the determinants of the heme sliding mechanism, suggesting that the shift at the beginning of helix G precedes and drives this process. Mapping Hydrophobic Tunnels and Cavities in Neuroglobin with Noble Gas under Pressure.,Colloc'h N, Carpentier P, Montemiglio LC, Vallone B, Prange T Biophys J. 2017 Nov 3. pii: S0006-3495(17)31129-3. doi:, 10.1016/j.bpj.2017.10.014. PMID:29108649[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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