Ligand pathways in neuroglobin revealed by low-temperature photodissociation and docking experiments

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Ardiccioni, Chiara | Arcovito, Alessandro | Della Longa, Stefano | van der Linden, Peter | Bourgeois, Dominique | Weik, Martin | Montemiglio, Linda, Celeste | Savino, Carmelinda | Avella, Giovanna | Exertier, Cécile | Carpentier, Philippe | Prangé, Thierry | Brunori, Maurizio | Colloc'H, Nathalie | Vallone, Beatrice

Edité par CCSD ; International Union of Crystallography -

CERVOXY COLL. International audience. A combined biophysical approach was applied to map gas-docking sites within murine neuroglobin (Ngb), revealing snapshots of events that might govern activity and dynamics in this unique hexacoordinate globin, which is most likely to be involved in gas-sensing in the central nervous system and for which a precise mechanism of action remains to be elucidated. The application of UV-visible microspectroscopy in crystallo, solution X-ray absorption near-edge spectroscopy and X-ray diffraction experiments at 15-40 K provided the structural characterization of an Ngb photolytic intermediate by cryo-trapping and allowed direct observation of the relocation of carbon monoxide within the distal heme pocket after photodissociation. Moreover, X-ray diffraction at 100 K under a high pressure of dioxygen, a physiological ligand of Ngb, unravelled the existence of a storage site for O2 in Ngb which coincides with Xe-III, a previously described docking site for xenon or krypton. Notably, no other secondary sites were observed under our experimental conditions.

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