Ligand pathways in neuroglobin revealed by low-temperature photodissociation and docking experiments.
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;
iucrj2019Vol. 6pp. 832-842
323
ardiccioni2019ligandiucrj
Abstract
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 , 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 O 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.