The Experts below are selected from a list of 573 Experts worldwide ranked by ideXlab platform

Pierre-jean Corringer - One of the best experts on this subject based on the ideXlab platform.

  • electrostatics proton sensor and networks governing the gating transition in glic a proton gated pentameric ion channel
    Proceedings of the National Academy of Sciences of the United States of America, 2018
    Co-Authors: Kenichi Ataka, Pierre-jean Corringer, L Sauguet, Zaineb Fourati, Anais Menny, Patrice Koehl, Joachim Heberle, Marc Delarue
    Abstract:

    The pentameric ligand-gated ion channel (pLGIC) from Gloeobacter Violaceus (GLIC) has provided insightful structure–function views on the permeation process and the allosteric regulation of the pLGICs family. However, GLIC is activated by pH instead of a neurotransmitter and a clear picture for the gating transition driven by protons is still lacking. We used an electrostatics-based (finite difference Poisson–Boltzmann/Debye–Huckel) method to predict the acidities of all aspartic and glutamic residues in GLIC, both in its active and closed-channel states. Those residues with a predicted pKa close to the experimental pH50 were individually replaced by alanine and the resulting variant receptors were titrated by ATR/FTIR spectroscopy. E35, located in front of loop F far away from the orthosteric site, appears as the key proton sensor with a measured individual pKa at 5.8. In the GLIC open conformation, E35 is connected through a water-mediated hydrogen-bond network first to the highly conserved electrostatic triad R192-D122-D32 and then to Y197-Y119-K248, both located at the extracellular domain–transmembrane domain interface. The second triad controls a cluster of hydrophobic side chains from the M2-M3 loop that is remodeled during the gating transition. We solved 12 crystal structures of GLIC mutants, 6 of them being trapped in an agonist-bound but nonconductive conformation. Combined with previous data, this reveals two branches of a continuous network originating from E35 that reach, independently, the middle transmembrane region of two adjacent subunits. We conclude that GLIC’s gating proceeds by making use of loop F, already known as an allosteric site in other pLGICs, instead of the classic orthosteric site.

  • Full mutational mapping of titratable residues helps to identify proton-sensors involved in the control of channel gating in the Gloeobacter Violaceus pentameric ligand-gated ion channel
    PLoS Biology, 2017
    Co-Authors: Ákos Nemecz, Marc Delarue, Catherine Van Renterghem, Zaineb Fourati, Pierre-jean Corringer
    Abstract:

    The Gloeobacter Violaceus ligand-gated ion channel (GLIC) has been extensively studied by X-ray crystallography and other biophysical techniques. This provided key insights into the general gating mechanism of pentameric ligand-gated ion channel (pLGIC) signal transduction. However, the GLIC is activated by lowering the pH and the location of its putative proton activation site(s) still remain(s) unknown. To this end, every Asp, Glu, and His residue was mutated individually or in combination and investigated by electrophysiology. In addition to the mutational analysis, key mutations were structurally resolved to address whether particular residues contribute to proton sensing, or alternatively to GLIC-gating, independently of the side chain protonation. The data show that multiple residues located below the orthosteric site, notably E26, D32, E35, and D122 in the lower part of the extracellular domain (ECD), along with E222, H235, E243, and H277 in the transmembrane domain (TMD), alter GLIC activation. D122 and H235 were found to also alter GLIC expression. E35 is identified as a key proton-sensing residue, whereby neutralization of its side chain carboxylate stabilizes the active state. Thus, proton activation occurs allosterically to the orthosteric site, at the level of multiple loci with a key contribution of the coupling interface between the ECD and TMD.

  • Unravelling the Conformational Plasticity of the Extracellular Domain of a Prokaryotic nAChR Homologue in Solution by NMR
    2016
    Co-Authors: Christos T. Chasapis, Pierre-jean Corringer, Aikaterini I. Argyriou, Detlef Bentrop, Georgios A. Spyroulias
    Abstract:

    Pentameric ligand-gated ion channels (pLGICs) of the Cys loop family are transmembrane glycoproteins implicated in a variety of biological functions. Here, we present a solution NMR study of the extracellular domain of a prokaryotic pLGIC homologue from the bacterium Gloeobacter Violaceus that is found to be a monomer in solution

  • ethanol modulation is quantitatively determined by the transmembrane domain of human α1 glycine receptors
    Alcoholism: Clinical and Experimental Research, 2015
    Co-Authors: Suzzane Horani, Pierre-jean Corringer, Rebecca J Howard, James R Trudell, Evan Stater, Adron R Harris
    Abstract:

    BACKGROUND Mutagenesis and labeling studies have identified amino acids from the human α1 glycine receptor (GlyR) extracellular, transmembrane (TM), and intracellular domains in mediating ethanol (EtOH) potentiation. However, limited high-resolution structural data for physiologically relevant receptors in this Cys-loop receptor superfamily have made pinpointing the critical amino acids difficult. Homologous ion channels from lower organisms provide conserved models for structural and functional properties of Cys-loop receptors. We previously demonstrated that a single amino acid variant of the Gloeobacter Violaceus ligand-gated ion channel (GLIC) produced EtOH and anesthetic sensitivity similar to that of GlyRs and provided crystallographic evidence for EtOH binding to GLIC. METHODS We directly compared EtOH modulation of the α1 GlyR and GLIC to a chimera containing the TM domain from human α1 GlyRs and the ligand-binding domain of GLIC using 2-electrode voltage-clamp electrophysiology of receptors expressed in Xenopus laevis oocytes. RESULTS EtOH potentiated α1 GlyRs in a concentration-dependent manner in the presence of zinc-chelating agents, but did not potentiate GLIC at pharmacologically relevant concentrations. The GLIC/GlyR chimera recapitulated the EtOH potentiation of GlyRs, without apparent sensitivity to zinc chelation. For chimera expression in oocytes, it was essential to suppress leakage current by adding 50 μM picrotoxin to the media, a technique that may have applications in expression of other ion channels. CONCLUSIONS Our results are consistent with a TM mechanism of EtOH modulation in Cys-loop receptors. This work highlights the relevance of bacterial homologs as valuable model systems for studying ion channel function of human receptors and demonstrates the modularity of these channels across species.

  • Identification of Cinnamic Acid Derivatives As Novel Antagonists of the Prokaryotic Proton-Gated Ion Channel GLIC
    Journal of Medicinal Chemistry, 2013
    Co-Authors: Marie Prevost, Pierre-jean Corringer, Catherine Van Renterghem, Sandrine Delarue-cochin, Justine Marteaux, Claire Colas, Arnaud Blondel, Thérèse Malliavin, Delphine Joseph
    Abstract:

    Pentameric ligand gated ion channels (pLGICs) mediate signal transduction. The binding of an extracellular ligand is coupled to the transmembrane channel opening. So far, all known agonists bind at the interface between subunits in a topologically conserved "orthosteric site" whose amino acid composition defines the pharmacological specificity of pLGIC subtypes. A striking exception is the bacterial proton-activated GLIC protein, exhibiting an uncommon orthosteric binding site in terms of sequence and local architecture. Among a library of Gloeobacter Violaceus metabolites, we identified a series of cinnamic acid derivatives, which antagonize the GLIC proton-elicited response. Structure-activity analysis shows a key contribution of the carboxylate moiety to GLIC inhibition. Molecular docking coupled to site-directed mutagenesis support that the binding pocket is located below the classical orthosteric site. These antagonists provide new tools to modulate conformation of GLIC, currently used as a prototypic pLGIC, and opens new avenues to study the signal transduction mechanism.

Marc Delarue - One of the best experts on this subject based on the ideXlab platform.

  • electrostatics proton sensor and networks governing the gating transition in glic a proton gated pentameric ion channel
    Proceedings of the National Academy of Sciences of the United States of America, 2018
    Co-Authors: Kenichi Ataka, Pierre-jean Corringer, L Sauguet, Zaineb Fourati, Anais Menny, Patrice Koehl, Joachim Heberle, Marc Delarue
    Abstract:

    The pentameric ligand-gated ion channel (pLGIC) from Gloeobacter Violaceus (GLIC) has provided insightful structure–function views on the permeation process and the allosteric regulation of the pLGICs family. However, GLIC is activated by pH instead of a neurotransmitter and a clear picture for the gating transition driven by protons is still lacking. We used an electrostatics-based (finite difference Poisson–Boltzmann/Debye–Huckel) method to predict the acidities of all aspartic and glutamic residues in GLIC, both in its active and closed-channel states. Those residues with a predicted pKa close to the experimental pH50 were individually replaced by alanine and the resulting variant receptors were titrated by ATR/FTIR spectroscopy. E35, located in front of loop F far away from the orthosteric site, appears as the key proton sensor with a measured individual pKa at 5.8. In the GLIC open conformation, E35 is connected through a water-mediated hydrogen-bond network first to the highly conserved electrostatic triad R192-D122-D32 and then to Y197-Y119-K248, both located at the extracellular domain–transmembrane domain interface. The second triad controls a cluster of hydrophobic side chains from the M2-M3 loop that is remodeled during the gating transition. We solved 12 crystal structures of GLIC mutants, 6 of them being trapped in an agonist-bound but nonconductive conformation. Combined with previous data, this reveals two branches of a continuous network originating from E35 that reach, independently, the middle transmembrane region of two adjacent subunits. We conclude that GLIC’s gating proceeds by making use of loop F, already known as an allosteric site in other pLGICs, instead of the classic orthosteric site.

  • Full mutational mapping of titratable residues helps to identify proton-sensors involved in the control of channel gating in the Gloeobacter Violaceus pentameric ligand-gated ion channel
    PLoS Biology, 2017
    Co-Authors: Ákos Nemecz, Marc Delarue, Catherine Van Renterghem, Zaineb Fourati, Pierre-jean Corringer
    Abstract:

    The Gloeobacter Violaceus ligand-gated ion channel (GLIC) has been extensively studied by X-ray crystallography and other biophysical techniques. This provided key insights into the general gating mechanism of pentameric ligand-gated ion channel (pLGIC) signal transduction. However, the GLIC is activated by lowering the pH and the location of its putative proton activation site(s) still remain(s) unknown. To this end, every Asp, Glu, and His residue was mutated individually or in combination and investigated by electrophysiology. In addition to the mutational analysis, key mutations were structurally resolved to address whether particular residues contribute to proton sensing, or alternatively to GLIC-gating, independently of the side chain protonation. The data show that multiple residues located below the orthosteric site, notably E26, D32, E35, and D122 in the lower part of the extracellular domain (ECD), along with E222, H235, E243, and H277 in the transmembrane domain (TMD), alter GLIC activation. D122 and H235 were found to also alter GLIC expression. E35 is identified as a key proton-sensing residue, whereby neutralization of its side chain carboxylate stabilizes the active state. Thus, proton activation occurs allosterically to the orthosteric site, at the level of multiple loci with a key contribution of the coupling interface between the ECD and TMD.

  • Structural basis for potentiation by alcohols and anaesthetics in a ligand-gated ion channel
    Nature Communications, 2013
    Co-Authors: L Sauguet, Pierre-jean Corringer, Rebecca Howard, Laurie Malherbe, Ui Lee, R. Adron Harris, Marc Delarue
    Abstract:

    Ethanol alters nerve signalling by interacting with proteins in the central nervous system, particularly pentameric ligand-gated ion channels. A recent series of mutagenesis experiments on Gloeobacter Violaceus ligand-gated ion channel, a prokaryotic member of this family, identified a single-site variant that is potentiated by pharmacologically relevant concentrations of ethanol. Here we determine crystal structures of the ethanol-sensitized variant in the absence and presence of ethanol and related modulators, which bind in a transmembrane cavity between channel subunits and may stabilize the open form of the channel. Structural and mutagenesis studies defined overlapping mechanisms of potentiation by alcohols and anaesthetics via the inter-subunit cavity. Furthermore, homology modelling show this cavity to be conserved in human ethanol-sensitive glycine and GABA(A) receptors, and to involve residues previously shown to influence alcohol and anaesthetic action on these proteins. These results suggest a common structural basis for ethanol potentiation of an important class of targets for neurological actions of ethanol.

  • one microsecond molecular dynamics simulation of channel gating in a nicotinic receptor homologue
    Proceedings of the National Academy of Sciences of the United States of America, 2010
    Co-Authors: Hugues Nury, Jean-pierre Changeux, Pierre-jean Corringer, Catherine Van Renterghem, Marc Delarue, Frederic Poitevin, Marc Baaden
    Abstract:

    Recently discovered bacterial homologues of eukaryotic pentameric ligand-gated ion channels, such as the Gloeobacter Violaceus receptor (GLIC), are increasingly used as structural and functional models of signal transduction in the nervous system. Here we present a one-microsecond-long molecular dynamics simulation of the GLIC channel pH stimulated gating mechanism. The crystal structure of GLIC obtained at acidic pH in an open-channel form is equilibrated in a membrane environment and then instantly set to neutral pH. The simulation shows a channel closure that rapidly takes place at the level of the hydrophobic furrow and a progressively increasing quaternary twist. Two major events are captured during the simulation. They are initiated by local but large fluctuations in the pore, taking place at the top of the M2 helix, followed by a global tertiary relaxation. The two-step transition of the first subunit starts within the first 50 ns of the simulation and is followed at 450 ns by its immediate neighbor in the pentamer, which proceeds with a similar scenario. This observation suggests a possible two-step domino-like tertiary mechanism that takes place between adjacent subunits. In addition, the dynamical properties of GLIC described here offer an interpretation of the paradoxical properties of a permeable A13'F mutant whose crystal structure determined at 3.15 A shows a pore too narrow to conduct ions.

  • Crystal Structure of the Extracellular Domain of a Bacterial Ligand-Gated Ion Channel
    Journal of Molecular Biology, 2010
    Co-Authors: Hugues Nury, Pierre-jean Corringer, Nicolas Bocquet, Chantal Le Poupon, Bertrand Raynal, Ahmed Haouz, Marc Delarue
    Abstract:

    The crystal structure of the extracellular domain (ECD) of the pentameric ligand-gated ion-channel from Gloeobacter Violaceus (GLIC) was solved at neutral pH at 2.3 A resolution in two crystal forms, showing a surprising hexameric quaternary structure with a 6-fold axis replacing the expected 5-fold axis. While each subunit retains the usual beta-sandwich immunoglobulin-like fold, small deviations from the whole GLIC structure indicate zones of differential flexibility. The changes in interface between two adjacent subunits in the pentamer and the hexamer can be described in a downward translation by one inter-strand distance and a global rotation of the second subunit, using the first one for superposition. While global characteristics of the interface, such as the buried accessible surface area, do not change very much, most of the atom-atom interactions are rearranged. It thus appears that the transmembrane domain is necessary for the proper oligomeric assembly of GLIC and that there is an intrinsic plasticity or polymorphism in possible subunit-subunit interfaces at the ECD level, the latter behaving as a monomer in solution. Possible functional implications of these novel structural data are discussed in the context of the allosteric transition of this family of proteins. In addition, we propose a novel way to quantify elastic energy stored in the interface between subunits, which indicates a tenser interface for the open form than for the closed form (rest state). The hexameric or pentameric forms of the ECD have a similar negative curvature in their subunit-subunit interface, while acetylcholine binding proteins have a smaller and positive curvature that increases from the apo to the holo form.

Jean-pierre Changeux - One of the best experts on this subject based on the ideXlab platform.

  • x ray structures of general anaesthetics bound to a pentameric ligand gated ion channel
    Nature, 2011
    Co-Authors: Hugues Nury, Jean-pierre Changeux, Catherine Van Renterghem, Yun Weng, Marc Baaden, Alphonso Tran, Virginie Dufresne
    Abstract:

    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) (γ-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.

  • one microsecond molecular dynamics simulation of channel gating in a nicotinic receptor homologue
    Proceedings of the National Academy of Sciences of the United States of America, 2010
    Co-Authors: Hugues Nury, Jean-pierre Changeux, Pierre-jean Corringer, Catherine Van Renterghem, Marc Delarue, Frederic Poitevin, Marc Baaden
    Abstract:

    Recently discovered bacterial homologues of eukaryotic pentameric ligand-gated ion channels, such as the Gloeobacter Violaceus receptor (GLIC), are increasingly used as structural and functional models of signal transduction in the nervous system. Here we present a one-microsecond-long molecular dynamics simulation of the GLIC channel pH stimulated gating mechanism. The crystal structure of GLIC obtained at acidic pH in an open-channel form is equilibrated in a membrane environment and then instantly set to neutral pH. The simulation shows a channel closure that rapidly takes place at the level of the hydrophobic furrow and a progressively increasing quaternary twist. Two major events are captured during the simulation. They are initiated by local but large fluctuations in the pore, taking place at the top of the M2 helix, followed by a global tertiary relaxation. The two-step transition of the first subunit starts within the first 50 ns of the simulation and is followed at 450 ns by its immediate neighbor in the pentamer, which proceeds with a similar scenario. This observation suggests a possible two-step domino-like tertiary mechanism that takes place between adjacent subunits. In addition, the dynamical properties of GLIC described here offer an interpretation of the paradoxical properties of a permeable A13'F mutant whose crystal structure determined at 3.15 A shows a pore too narrow to conduct ions.

  • X-ray structure of a pentameric ligand-gated ion channel in an apparently open conformation
    Nature, 2009
    Co-Authors: Nicolas Bocquet, Jean-pierre Changeux, Hugues Nury, Marc Delarue, Marc Baaden, Chantal Le Poupon, Pierre-jean Corringer
    Abstract:

    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.

  • a prokaryotic proton gated ion channel from the nicotinic acetylcholine receptor family
    Nature, 2007
    Co-Authors: Nicolas Bocquet, Jean-pierre Changeux, Lia Prado De Carvalho, Jean Cartaud, Jacques Neyton, Chantal Le Poupon, Antoine Taly, Thomas Grutter, Pierre-jean Corringer
    Abstract:

    Ligand-gated ion channels (LGICs) mediate excitatory and inhibitory transmission in the nervous system. Among them, the pentameric or 'Cys-loop' receptors (pLGICs) compose a family that until recently was found in only eukaryotes. Yet a recent genome search identified putative homologues of these proteins in several bacterial species. Here we report the cloning, expression and functional identification of one of these putative homologues from the cyanobacterium Gloeobacter Violaceus. It was expressed as a homo-oligomer in HEK 293 cells and Xenopus oocytes, generating a transmembrane cationic channel that is opened by extracellular protons and shows slow kinetics of activation, no desensitization and a single channel conductance of 8 pS. Electron microscopy and cross-linking experiments of the protein fused to the maltose-binding protein and expressed in Escherichia coli are consistent with a homo-pentameric organization. Sequence comparison shows that it possesses a compact structure, with the absence of the amino-terminal helix, the canonical disulphide bridge and the large cytoplasmic domain found in eukaryotic pLGICs. Therefore it embodies a minimal structure required for signal transduction. These data establish the prokaryotic origin of the family. Because Gloeobacter Violaceus carries out photosynthesis and proton transport at the cytoplasmic membrane, this new proton-gated ion channel might contribute to adaptation to pH change.

Catherine Van Renterghem - One of the best experts on this subject based on the ideXlab platform.

  • Full mutational mapping of titratable residues helps to identify proton-sensors involved in the control of channel gating in the Gloeobacter Violaceus pentameric ligand-gated ion channel
    PLoS Biology, 2017
    Co-Authors: Ákos Nemecz, Marc Delarue, Catherine Van Renterghem, Zaineb Fourati, Pierre-jean Corringer
    Abstract:

    The Gloeobacter Violaceus ligand-gated ion channel (GLIC) has been extensively studied by X-ray crystallography and other biophysical techniques. This provided key insights into the general gating mechanism of pentameric ligand-gated ion channel (pLGIC) signal transduction. However, the GLIC is activated by lowering the pH and the location of its putative proton activation site(s) still remain(s) unknown. To this end, every Asp, Glu, and His residue was mutated individually or in combination and investigated by electrophysiology. In addition to the mutational analysis, key mutations were structurally resolved to address whether particular residues contribute to proton sensing, or alternatively to GLIC-gating, independently of the side chain protonation. The data show that multiple residues located below the orthosteric site, notably E26, D32, E35, and D122 in the lower part of the extracellular domain (ECD), along with E222, H235, E243, and H277 in the transmembrane domain (TMD), alter GLIC activation. D122 and H235 were found to also alter GLIC expression. E35 is identified as a key proton-sensing residue, whereby neutralization of its side chain carboxylate stabilizes the active state. Thus, proton activation occurs allosterically to the orthosteric site, at the level of multiple loci with a key contribution of the coupling interface between the ECD and TMD.

  • Identification of Cinnamic Acid Derivatives As Novel Antagonists of the Prokaryotic Proton-Gated Ion Channel GLIC
    Journal of Medicinal Chemistry, 2013
    Co-Authors: Marie Prevost, Pierre-jean Corringer, Catherine Van Renterghem, Sandrine Delarue-cochin, Justine Marteaux, Claire Colas, Arnaud Blondel, Thérèse Malliavin, Delphine Joseph
    Abstract:

    Pentameric ligand gated ion channels (pLGICs) mediate signal transduction. The binding of an extracellular ligand is coupled to the transmembrane channel opening. So far, all known agonists bind at the interface between subunits in a topologically conserved "orthosteric site" whose amino acid composition defines the pharmacological specificity of pLGIC subtypes. A striking exception is the bacterial proton-activated GLIC protein, exhibiting an uncommon orthosteric binding site in terms of sequence and local architecture. Among a library of Gloeobacter Violaceus metabolites, we identified a series of cinnamic acid derivatives, which antagonize the GLIC proton-elicited response. Structure-activity analysis shows a key contribution of the carboxylate moiety to GLIC inhibition. Molecular docking coupled to site-directed mutagenesis support that the binding pocket is located below the classical orthosteric site. These antagonists provide new tools to modulate conformation of GLIC, currently used as a prototypic pLGIC, and opens new avenues to study the signal transduction mechanism.

  • Identification of Cinnamic Acid Derivatives As Novel Antagonists of the Prokaryotic Proton-Gated Ion Channel GLIC
    2013
    Co-Authors: Marie S. Prevost, Pierre-jean Corringer, Catherine Van Renterghem, Sandrine Delarue-cochin, Justine Marteaux, Claire Colas, Arnaud Blondel, Thérèse Malliavin, Delphine Joseph
    Abstract:

    Pentameric ligand gated ion channels (pLGICs) mediate signal transduction. The binding of an extracellular ligand is coupled to the transmembrane channel opening. So far, all known agonists bind at the interface between subunits in a topologically conserved “orthosteric site” whose amino acid composition defines the pharmacological specificity of pLGIC subtypes. A striking exception is the bacterial proton-activated GLIC protein, exhibiting an uncommon orthosteric binding site in terms of sequence and local architecture. Among a library of Gloeobacter Violaceus metabolites, we identified a series of cinnamic acid derivatives, which antagonize the GLIC proton-elicited response. Structure–activity analysis shows a key contribution of the carboxylate moiety to GLIC inhibition. Molecular docking coupled to site-directed mutagenesis support that the binding pocket is located below the classical orthosteric site. These antagonists provide new tools to modulate conformation of GLIC, currently used as a prototypic pLGIC, and opens new avenues to study the signal transduction mechanism

  • x ray structures of general anaesthetics bound to a pentameric ligand gated ion channel
    Nature, 2011
    Co-Authors: Hugues Nury, Jean-pierre Changeux, Catherine Van Renterghem, Yun Weng, Marc Baaden, Alphonso Tran, Virginie Dufresne
    Abstract:

    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) (γ-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.

  • one microsecond molecular dynamics simulation of channel gating in a nicotinic receptor homologue
    Proceedings of the National Academy of Sciences of the United States of America, 2010
    Co-Authors: Hugues Nury, Jean-pierre Changeux, Pierre-jean Corringer, Catherine Van Renterghem, Marc Delarue, Frederic Poitevin, Marc Baaden
    Abstract:

    Recently discovered bacterial homologues of eukaryotic pentameric ligand-gated ion channels, such as the Gloeobacter Violaceus receptor (GLIC), are increasingly used as structural and functional models of signal transduction in the nervous system. Here we present a one-microsecond-long molecular dynamics simulation of the GLIC channel pH stimulated gating mechanism. The crystal structure of GLIC obtained at acidic pH in an open-channel form is equilibrated in a membrane environment and then instantly set to neutral pH. The simulation shows a channel closure that rapidly takes place at the level of the hydrophobic furrow and a progressively increasing quaternary twist. Two major events are captured during the simulation. They are initiated by local but large fluctuations in the pore, taking place at the top of the M2 helix, followed by a global tertiary relaxation. The two-step transition of the first subunit starts within the first 50 ns of the simulation and is followed at 450 ns by its immediate neighbor in the pentamer, which proceeds with a similar scenario. This observation suggests a possible two-step domino-like tertiary mechanism that takes place between adjacent subunits. In addition, the dynamical properties of GLIC described here offer an interpretation of the paradoxical properties of a permeable A13'F mutant whose crystal structure determined at 3.15 A shows a pore too narrow to conduct ions.

Corringer Pierre-jean - One of the best experts on this subject based on the ideXlab platform.

  • Electrostatics, proton sensor, and networks governing the gating transition in GLIC, a proton-gated pentameric ion channel
    'Proceedings of the National Academy of Sciences', 2018
    Co-Authors: Hu Haidai, Fourati Zaineb, Corringer Pierre-jean, Sauguet Ludovic, Ataka Kenichi, Menny Anaïs, Koehl Patrice, Heberle Joachim, Delarue Marc
    Abstract:

    International audienceThe pentameric ligand-gated ion channel (pLGIC) from Gloeobacter Violaceus (GLIC) has provided insightful structure-function views on the permeation process and the allosteric regulation of the pLGICs family. However, GLIC is activated by pH instead of a neurotransmitter and a clear picture for the gating transition driven by protons is still lacking. We used an electrostatics-based (finite difference Poisson-Boltzmann/Debye-Hückel) method to predict the acidities of all aspartic and glutamic residues in GLIC, both in its active and closed-channel states. Those residues with a predicted pKa close to the experimental pH50 were individually replaced by alanine and the resulting variant receptors were titrated by ATR/FTIR spectroscopy. E35, located in front of loop F far away from the orthosteric site, appears as the key proton sensor with a measured individual pKa at 5.8. In the GLIC open conformation, E35 is connected through a water-mediated hydrogen-bond network first to the highly conserved electrostatic triad R192-D122-D32 and then to Y197-Y119-K248, both located at the extracellular domain-transmembrane domain interface. The second triad controls a cluster of hydrophobic side chains from the M2-M3 loop that is remodeled during the gating transition. We solved 12 crystal structures of GLIC mutants, 6 of them being trapped in an agonist-bound but nonconductive conformation. Combined with previous data, this reveals two branches of a continuous network originating from E35 that reach, independently, the middle transmembrane region of two adjacent subunits. We conclude that GLIC's gating proceeds by making use of loop F, already known as an allosteric site in other pLGICs, instead of the classic orthosteric site

  • Full mutational mapping of titratable residues helps to identify proton-sensors involved in the control of channel gating in the Gloeobacter Violaceus pentameric ligand-gated ion channel
    'Public Library of Science (PLoS)', 2017
    Co-Authors: Nemecz Ákos, Hu Haidai, Fourati Zaineb, Van Renterghem Catherine, Delarue Marc, Corringer Pierre-jean
    Abstract:

    International audienceThe Gloeobacter Violaceus ligand-gated ion channel (GLIC) has been extensively studied by X-ray crystallography and other biophysical techniques. This provided key insights into the general gating mechanism of pentameric ligand-gated ion channel (pLGIC) signal transduction. However, the GLIC is activated by lowering the pH and the location of its putative proton activation site(s) still remain(s) unknown. To this end, every Asp, Glu, and His residue was mutated individually or in combination and investigated by electrophysiology. In addition to the mutational analysis, key mutations were structurally resolved to address whether particular residues contribute to proton sensing, or alternatively to GLIC-gating, independently of the side chain protonation. The data show that multiple residues located below the orthosteric site, notably E26, D32, E35, and D122 in the lower part of the extracellular domain (ECD), along with E222, H235, E243, and H277 in the transmembrane domain (TMD), alter GLIC activation. D122 and H235 were found to also alter GLIC expression. E35 is identified as a key proton-sensing residue, whereby neutralization of its side chain carboxylate stabilizes the active state. Thus, proton activation occurs allosterically to the orthosteric site, at the level of multiple loci with a key contribution of the coupling interface between the ECD and TMD

  • Ethanol Modulation is Quantitatively Determined by the Transmembrane Domain of Human α 1 Glycine Receptors
    'Wiley', 2015
    Co-Authors: Horani Suzzane, Corringer Pierre-jean, Stater Evan, Trudell James, Harris R. Adron, Howard Rebecca
    Abstract:

    International audienceMutagenesis and labeling studies have identified amino acids from the human α1 glycine receptor (GlyR) extracellular, transmembrane (TM), and intracellular domains in mediating ethanol (EtOH) potentiation. However, limited high-resolution structural data for physiologically relevant receptors in this Cys-loop receptor superfamily have made pinpointing the critical amino acids difficult. Homologous ion channels from lower organisms provide conserved models for structural and functional properties of Cys-loop receptors. We previously demonstrated that a single amino acid variant of the Gloeobacter Violaceus ligand-gated ion channel (GLIC) produced EtOH and anesthetic sensitivity similar to that of GlyRs and provided crystallographic evidence for EtOH binding to GLIC

  • Identification of Cinnamic Acid Derivatives As Novel Antagonists of the Prokaryotic Proton-Gated Ion Channel GLIC
    'American Chemical Society (ACS)', 2013
    Co-Authors: Prevost Marie, Van Renterghem Catherine, Corringer Pierre-jean, Delarue-cochin Sandrine, Marteaux Justine, Colas Claire, Blondel Arnaud, Malliavin Thérèse, Joseph Delphine
    Abstract:

    International audiencePentameric ligand gated ion channels (pLGICs) mediate signal transduction. The binding of an extracellular ligand is coupled to the transmembrane channel opening. So far, all known agonists bind at the interface between subunits in a topologically conserved "orthosteric site" whose amino acid composition defines the pharmacological specificity of pLGIC subtypes. A striking exception is the bacterial proton-activated GLIC protein, exhibiting an uncommon orthosteric binding site in terms of sequence and local architecture. Among a library of Gloeobacter Violaceus metabolites, we identified a series of cinnamic acid derivatives, which antagonize the GLIC proton-elicited response. Structure-activity analysis shows a key contribution of the carboxylate moiety to GLIC inhibition. Molecular docking coupled to site-directed mutagenesis support that the binding pocket is located below the classical orthosteric site. These antagonists provide new tools to modulate conformation of GLIC, currently used as a prototypic pLGIC, and opens new avenues to study the signal transduction mechanism

  • Structural basis for potentiation by alcohols and anaesthetics in a ligand-gated ion channel
    'Springer Science and Business Media LLC', 2013
    Co-Authors: Sauguet Ludovic, Ui Lee, Corringer Pierre-jean, Howard Rebecca, Malherbe Laurie, Adron Harris R., Delarue Marc
    Abstract:

    International audienceEthanol alters nerve signalling by interacting with proteins in the central nervous system, particularly pentameric ligand-gated ion channels. A recent series of mutagenesis experiments on Gloeobacter Violaceus ligand-gated ion channel, a prokaryotic member of this family, identified a single-site variant that is potentiated by pharmacologically relevant concentrations of ethanol. Here we determine crystal structures of the ethanol-sensitized variant in the absence and presence of ethanol and related modulators, which bind in a transmembrane cavity between channel subunits and may stabilize the open form of the channel. Structural and mutagenesis studies defined overlapping mechanisms of potentiation by alcohols and anaesthetics via the inter-subunit cavity. Furthermore, homology modelling show this cavity to be conserved in human ethanol-sensitive glycine and GABA(A) receptors, and to involve residues previously shown to influence alcohol and anaesthetic action on these proteins. These results suggest a common structural basis for ethanol potentiation of an important class of targets for neurological actions of ethanol