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  • 1
    Publication Date: 2011-01-21
    Description: General anaesthetics have enjoyed long and widespread use but their molecular mechanism of action remains poorly understood. There is good evidence that their principal targets are pentameric ligand-gated ion channels (pLGICs) such as inhibitory GABA(A) (gamma-aminobutyric acid) receptors and excitatory nicotinic acetylcholine receptors, which are respectively potentiated and inhibited by general anaesthetics. The bacterial homologue from Gloeobacter violaceus (GLIC), whose X-ray structure was recently solved, is also sensitive to clinical concentrations of general anaesthetics. Here we describe the crystal structures of the complexes propofol/GLIC and desflurane/GLIC. These reveal a common general-anaesthetic binding site, which pre-exists in the apo-structure in the upper part of the transmembrane domain of each protomer. Both molecules establish van der Waals interactions with the protein; propofol binds at the entrance of the cavity whereas the smaller, more flexible, desflurane binds deeper inside. Mutations of some amino acids lining the binding site profoundly alter the ionic response of GLIC to protons, and affect its general-anaesthetic pharmacology. Molecular dynamics simulations, performed on the wild type (WT) and two GLIC mutants, highlight differences in mobility of propofol in its binding site and help to explain these effects. These data provide a novel structural framework for the design of general anaesthetics and of allosteric modulators of brain pLGICs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nury, Hugues -- Van Renterghem, Catherine -- Weng, Yun -- Tran, Alphonso -- Baaden, Marc -- Dufresne, Virginie -- Changeux, Jean-Pierre -- Sonner, James M -- Delarue, Marc -- Corringer, Pierre-Jean -- R01 GM069379/GM/NIGMS NIH HHS/ -- England -- Nature. 2011 Jan 20;469(7330):428-31. doi: 10.1038/nature09647.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut Pasteur, Groupe Recepteurs-Canaux, F-75015 Paris, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21248852" target="_blank"〉PubMed〈/a〉
    Keywords: Anesthetics, General/*chemistry/*metabolism ; Binding Sites/genetics ; Crystallography, X-Ray ; Cyanobacteria/*chemistry ; Electrophysiological Phenomena ; Isoflurane/*analogs & derivatives/chemistry/metabolism ; Ligand-Gated Ion Channels/*chemistry/genetics/*metabolism ; Ligands ; Models, Molecular ; Molecular Dynamics Simulation ; Mutant Proteins/chemistry/genetics/metabolism ; Propofol/*chemistry/metabolism ; Protein Binding ; Protein Structure, Tertiary ; Protons
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2008-11-07
    Description: Pentameric ligand-gated ion channels 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 A resolution of the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel homologue (GLIC) at pH 4.6 in an apparently 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 A constriction matches with rings of hydrophilic residues that are likely to contribute to the ionic selectivity. Structural comparison with ELIC, a bacterial homologue from Erwinia chrysanthemi solved in a presumed 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 alpha-helices away from the pore axis. These data are consistent with a model of pore opening based on both quaternary twist and tertiary deformation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bocquet, Nicolas -- Nury, Hugues -- Baaden, Marc -- Le Poupon, Chantal -- Changeux, Jean-Pierre -- Delarue, Marc -- Corringer, Pierre-Jean -- England -- Nature. 2009 Jan 1;457(7225):111-4. doi: 10.1038/nature07462. Epub 2008 Nov 5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Pasteur Institute, G5 Group of Channel-Receptor, CNRS URA 2182.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18987633" target="_blank"〉PubMed〈/a〉
    Keywords: Crystallography, X-Ray ; Cyanobacteria/*chemistry ; Hydrophobic and Hydrophilic Interactions ; *Ion Channel Gating ; Ion Channels/*chemistry/*metabolism ; Ligands ; Models, Molecular ; Pectobacterium chrysanthemi/chemistry ; Protein Structure, Quaternary ; Protein Subunits/chemistry/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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