Pore conformations and gating mechanism of a Cys-loop receptor.
Neurons regulate the propagation of chemoelectric signals throughout the nervous system by opening and closing ion channels, a process known as gating. Here, histidine-based metal-binding sites were engineered along the intrinsic pore of a chimeric Cys-loop receptor to probe state-dependent Zn(2+)-channel interactions. Patterns of Zn(2+) ion binding within the pore reveal that, in the closed state, the five pore-lining segments adopt an oblique orientation relative to the axis of ion conduction and constrict into a physical gate at their intracellular end. The interactions of Zn(2+) with the open state indicate that the five pore-lining segments should rigidly tilt to enable the movement of their intracellular ends away from the axis of ion conduction, so as to open the constriction (i.e., the gate). Alignment of the functional results with the 3D structure of an acetylcholine receptor allowed us to generate structural models accounting for the closed and open pore conformations and for a gating mechanism of a Cys-loop receptor.
Paas
Yoav
Y
Récepteurs et Cognition, Unité de Recherche Associée 2182 Centre National de la Recherche Scientifique, Institut Pasteur, 25 Rue du Docteur Roux, 75724 Paris Cedex 15, France. yopaas@netvision.net.il
Gibor
Gilad
G
Grailhe
Regis
R
Savatier-Duclert
Nathalie
N
Dufresne
Virginie
V
Sunesen
Morten
M
de Carvalho
Lia Prado
LP
Changeux
Jean-Pierre
JP
Attali
Bernard
B
D000818:Animals; D002460:Cell Line; D002463:Cell Membrane Permeability; D004594:Electrophysiology; D006801:Humans; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry* / Q000502:physiology*; D009474:Neurons / Q000737:chemistry; D009865:Oocytes; D016062:Porosity; D011487:Protein Conformation; D015202:Protein Engineering; D011950:Receptors, Cholinergic / Q000737:chemistry; D011993:Recombinant Fusion Proteins; D014981:Xenopus; D015032:Zinc / Q000378:metabolism
D007473:Ion Channels; D011950:Receptors, Cholinergic; D011993:Recombinant Fusion Proteins; D015032:Zinc