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Post-Doc positions are available to carry crystallographic and biophysical approches on bacterial pLGICs
X-ray structure of a bacterial pentameric ligand-gated ion channel in an apparently open conformation
Nicolas Bocquet*, Hugues Nury*, Marc Baaden, Chantal Le Poupon, Jean-Pierre Changeux, Marc Delarue#, Pierre-Jean Corringer#
Pentameric ligand-gated ion channels (pLGICs) from the cys-loop family mediate fast chemo-electrical transduction, but the mechanisms of ion permeation and gating of these membrane proteins remain elusive. Here we present the X-ray structure at 2.9 Å resolution of the bacterial Gloeobacter violaceus pLGIC homolog (GLIC) at pH 4.6 in a presumptively open conformation. This cationic channel is known to be permanently activated by protons. The structure is arranged as a funnel-shaped transmembrane pore widely open on the outer side and lined by hydrophobic residues. On the inner side, a 5 Å constriction matches with rings of hydrophilic residues likely to contribute to the ionic selectivity. Structural comparison with ELIC, a bacterial homolog from Erwinia chrysanthemi solved in a presumptively closed conformation, shows a wider pore where the narrow hydrophobic constriction found in ELIC is removed. Comparative analysis of GLIC and ELIC reveals, in concert, a rotation of each extracellular beta-sandwich domain as a rigid-body, interface rearrangements, and a reorganization of the transmembrane domain, involving a tilt of the M2 and M3 ?-helices away from the pore axis. These data are consistent with a model of pore opening based on both quaternary twist and tertiary deformation.
Post-Doc positions are available to carry crystallographic and biophysical approches on bacterial pLGICs
X-ray structure of a bacterial pentameric ligand-gated ion channel in an apparently open conformation
Nicolas Bocquet*, Hugues Nury*, Marc Baaden, Chantal Le Poupon, Jean-Pierre Changeux, Marc Delarue#, Pierre-Jean Corringer#
Pentameric ligand-gated ion channels (pLGICs) from the cys-loop family mediate fast chemo-electrical transduction, but the mechanisms of ion permeation and gating of these membrane proteins remain elusive. Here we present the X-ray structure at 2.9 Å resolution of the bacterial Gloeobacter violaceus pLGIC homolog (GLIC) at pH 4.6 in a presumptively open conformation. This cationic channel is known to be permanently activated by protons. The structure is arranged as a funnel-shaped transmembrane pore widely open on the outer side and lined by hydrophobic residues. On the inner side, a 5 Å constriction matches with rings of hydrophilic residues likely to contribute to the ionic selectivity. Structural comparison with ELIC, a bacterial homolog from Erwinia chrysanthemi solved in a presumptively closed conformation, shows a wider pore where the narrow hydrophobic constriction found in ELIC is removed. Comparative analysis of GLIC and ELIC reveals, in concert, a rotation of each extracellular beta-sandwich domain as a rigid-body, interface rearrangements, and a reorganization of the transmembrane domain, involving a tilt of the M2 and M3 ?-helices away from the pore axis. These data are consistent with a model of pore opening based on both quaternary twist and tertiary deformation.