Multisite binding of a general anesthetic to the prokaryotic pentameric Erwinia chrysanthemi ligand-gated ion channel (ELIC).
Pentameric ligand-gated ion channels (pLGICs), such as nicotinic acetylcholine, glycine, γ-aminobutyric acid GABA(A/C) receptors, and the Gloeobacter violaceus ligand-gated ion channel (GLIC), are receptors that contain multiple allosteric binding sites for a variety of therapeutics, including general anesthetics. Here, we report the x-ray crystal structure of the Erwinia chrysanthemi ligand-gated ion channel (ELIC) in complex with a derivative of chloroform, which reveals important features of anesthetic recognition, involving multiple binding at three different sites. One site is located in the channel pore and equates with a noncompetitive inhibitor site found in many pLGICs. A second transmembrane site is novel and is located in the lower part of the transmembrane domain, at an interface formed between adjacent subunits. A third site is also novel and is located in the extracellular domain in a hydrophobic pocket between the β7-β10 strands. Together, these results extend our understanding of pLGIC modulation and reveal several specific binding interactions that may contribute to modulator recognition, further substantiating a multisite model of allosteric modulation in this family of ion channels.
Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, PB 601, B-3000 Leuven, Belgium.
Radovan
R
Spurny
Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, PB 601, B-3000 Leuven, Belgium.
Bert
B
Billen
Waggoner Center for Alcohol and Addiction Research, The University of Texas, Austin, Texas 78712.
Rebecca J
RJ
Howard
Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, PB 601, B-3000 Leuven, Belgium.
Marijke
M
Brams
Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, PB 601, B-3000 Leuven, Belgium.
Sarah
S
Debaveye
Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB 1QW, United Kingdom.
Kerry L
KL
Price
Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB 1QW, United Kingdom.
David A
DA
Weston
Laboratory of Biocrystallography, KU Leuven, Herestraat 49, PB 822, B-3000 Leuven, Belgium.
Sergei V
SV
Strelkov
Laboratory of Toxicology, KU Leuven, Herestraat 49, PB 922, B-3000 Leuven, Belgium.
Jan
J
Tytgat
HiQScreen Sàrl, 15 rue de l'Athénée, Case Postale 209, CH-1211 Geneva 12, Switzerland.
Sonia
S
Bertrand
HiQScreen Sàrl, 15 rue de l'Athénée, Case Postale 209, CH-1211 Geneva 12, Switzerland.
Daniel
D
Bertrand
Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB 1QW, United Kingdom.
Sarah C R
SCR
Lummis
Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, PB 601, B-3000 Leuven, Belgium. Electronic address: chris.ulens@med.kuleuven.be.
Chris
C
Ulens
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D018685:Anesthetics, Inhalation / Q000737:chemistry*; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D002725:Chloroform / Q000737:chemistry / Q000494:pharmacology; D018360:Crystallography, X-Ray; D016974:Dickeya chrysanthemi; D058446:Ligand-Gated Ion Channels / Q000737:chemistry*; D008564:Membrane Potentials / Q000187:drug effects; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D011485:Protein Binding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D018009:Receptors, Glycine / Q000235:genetics / Q000378:metabolism; D022882:Trihalomethanes / Q000737:chemistry / Q000494:pharmacology; D014982:Xenopus laevis
D018685:Anesthetics, Inhalation; D001426:Bacterial Proteins; D058446:Ligand-Gated Ion Channels; D018009:Receptors, Glycine; D022882:Trihalomethanes; D002725:Chloroform; C015044:bromoform