title: Structural Basis of Alcohol Inhibition of the Pentameric Ligand-Gated Ion Channel ELIC.
abstract: The structural basis for alcohol modulation of neuronal pentameric ligand-gated ion channels (pLGICs) remains elusive. We determined an inhibitory mechanism of alcohol on the pLGIC Erwinia chrysanthemi (ELIC) through direct binding to the pore. X-ray structures of ELIC co-crystallized with 2-bromoethanol, in both the absence and presence of agonist, reveal 2-bromoethanol binding in the pore near T237(6') and the extracellular domain (ECD) of each subunit at three different locations. Binding to the ECD does not appear to contribute to the inhibitory action of 2-bromoethanol and ethanol as indicated by the same functional responses of wild-type ELIC and mutants. In contrast, the ELIC-α1β3GABAAR chimera, replacing the ELIC transmembrane domain (TMD) with the TMD of α1β3GABAAR, is potentiated by 2-bromoethanol and ethanol. The results suggest a dominant role of the TMD in modulating alcohol effects. The X-ray structures and functional measurements support a pore-blocking mechanism for inhibitory action of short-chain alcohols.
authors.affiliation: Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Computational and System Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA.
authors.forename: Marta M
authors.initials: MM
authors.lastname: Wells
authors.affiliation: Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
authors.forename: Tommy S
authors.initials: TS
authors.lastname: Tillman
authors.affiliation: Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
authors.forename: Monica N
authors.initials: MN
authors.lastname: Kinde
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
authors.forename: Aina
authors.initials: A
authors.lastname: Cohen
authors.affiliation: Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA; Department of Structural Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA; Department of Computational and System Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA. Electronic address: ptang@pitt.edu.
authors.forename: Pei
authors.initials: P
authors.lastname: Tang
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D016974:Dickeya chrysanthemi / Q000201:enzymology*; D000431:Ethanol / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D058446:Ligand-Gated Ion Channels / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics*; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D055503:Protein Multimerization
chemical_list: D058446:Ligand-Gated Ion Channels; D000431:Ethanol; C025475:ethylene bromohydrin
keywords: ELIC; alcohols; ethanol; pentameric ligand-gated ion channels; pore blocking