Emerging Molecular Mechanisms of Signal Transduction in Pentameric Ligand-Gated Ion Channels

Nemecz, Ákos; Prevost, Marie S.; Menny, A.; Corringer, Pierre‐Jean

doi:10.1016/j.neuron.2016.03.032

Cited by 212 publications

(362 citation statements)

References 205 publications

(269 reference statements)

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“…To enhance clarity in this figure several structures were grouped and classified as "closed," "open," and "desensitized," although we emphasize that subtle and important differences exists in, for example, the GLIC locally closed state (51) and the GluCl apo state (31), which we both classified as closed structures, but most likely represent "intermediate" conformational states (31,51). For a detailed discussion of the known conformational differences in currently available Cys-loop receptor structures, we refer to recent reviews (52,53). Notably, several additional sites have been identified using other methods, such as photoaffinity labeling and mutagenesis, but due to space limitation these results extend beyond the scope of the current discussion.…”

Section: Discussionmentioning

confidence: 99%

Allosteric binding site in a Cys-loop receptor ligand-binding domain unveiled in the crystal structure of ELIC in complex with chlorpromazine

Nys

Wijckmans

Farinha

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Pentameric ligand-gated ion channels or Cys-loop receptors are responsible for fast inhibitory or excitatory synaptic transmission. The antipsychotic compound chlorpromazine is a widely used tool to probe the ion channel pore of the nicotinic acetylcholine receptor, which is a prototypical Cys-loop receptor. In this study, we determine the molecular determinants of chlorpromazine binding in the Erwinia ligand-gated ion channel (ELIC). We report the X-ray crystal structures of ELIC in complex with chlorpromazine or its brominated derivative bromopromazine. Unexpectedly, we do not find a chlorpromazine molecule in the channel pore of ELIC, but behind the β8-β9 loop in the extracellular ligand-binding domain. The β8-β9 loop is localized downstream from the neurotransmitter binding site and plays an important role in coupling of ligand binding to channel opening. In combination with electrophysiological recordings from ELIC cysteine mutants and a thiol-reactive derivative of chlorpromazine, we demonstrate that chlorpromazine binding at the β8-β9 loop is responsible for receptor inhibition. We further use molecular-dynamics simulations to support the X-ray data and mutagenesis experiments. Together, these data unveil an allosteric binding site in the extracellular ligand-binding domain of ELIC. Our results extend on previous observations and further substantiate our understanding of a multisite model for allosteric modulation of Cys-loop receptors.ligand-gated ion channel | X-ray crystallography | allosteric modulation | Cys-loop receptor | nicotinic acetylcholine receptor C hlorpromazine (CPZ) (Fig. 1), a phenothiazine-derived antipsychotic drug, was introduced in psychiatry in the early 1950s, revolutionizing the treatment of psychotic disorders (1, 2). The main mechanism of action of CPZ consists in the blockage of dopamine receptors (2-4), but the numerous side effects associated with this drug indicate that it interacts with other physiologically relevant targets. CPZ was indeed shown to interfere with several voltage-and ligand-gated channels: it inhibits neuronal voltage-gated K + channels (5-7), BK Ca channels (8), and the human α 1E subunit-mediated Ca 2+ channels (9); CPZ was also shown to inhibit GABAergic currents (10, 11), specifically through GABA A receptors (GABA A Rs) (12), and to inhibit serotonin type-3 receptors (5-HT 3 Rs) (13, 14) and nicotinic acetylcholine receptors (nAChRs) (15, 16), members of the Cys-loop receptor family.The Cys-loop receptor family is composed of membranespanning ligand-gated ion channels that are responsible for fast excitatory or inhibitory synaptic neurotransmission. They are composed of five identical or nonidentical subunits, each of them comprising an N-terminal extracellular domain, which contains the neurotransmitter binding site, four transmembrane helices, that when assembled allow ions to pass through the membrane, and an intracellular domain, responsible for channel conductance, receptor modulation, and trafficking (17, 18). Initial structural insight into the ...

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Section: Discussionmentioning

confidence: 99%

Allosteric binding site in a Cys-loop receptor ligand-binding domain unveiled in the crystal structure of ELIC in complex with chlorpromazine

Nys

Wijckmans

Farinha

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Consequentially, nAChRs are drug targets for the treatment of severe pain, cognitive decline, epilepsy, and nicotine addiction [1,2,3,4,5]. α-Conotoxins, which come from sea Conus snails, are important tool for studying nAChRs.…”

Section: Introductionmentioning

confidence: 99%

Residues Responsible for the Selectivity of α-Conotoxins for Ac-AChBP or nAChRs

Lin

Xiang

2016

Marine Drugs

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Nicotinic acetylcholine receptors (nAChRs) are targets for developing new drugs to treat severe pain, nicotine addiction, Alzheimer disease, epilepsy, etc. α-Conotoxins are biologically and chemically diverse. With 12–19 residues and two disulfides, they can be specifically selected for different nAChRs. Acetylcholine-binding proteins from Aplysia californica (Ac-AChBP) are homologous to the ligand-binding domains of nAChRs and pharmacologically similar. X-ray structures of the α-conotoxin in complex with Ac-AChBP in addition to computer modeling have helped to determine the binding site of the important residues of α-conotoxin and its affinity for nAChR subtypes. Here, we present the various α-conotoxin residues that are selective for Ac-AChBP or nAChRs by comparing the structures of α-conotoxins in complex with Ac-AChBP and by modeling α-conotoxins in complex with nAChRs. The knowledge of these binding sites will assist in the discovery and design of more potent and selective α-conotoxins as drug leads.

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“…The overall architecture of the receptor was described in landmark studies of the nicotinic receptor isolated from the electric organ of Torpedo marmorata 5 . Structures of a soluble ligand binding domain have provided atomic-scale insights into receptor-ligand interactions 6 , while high-resolution structures of other members of the pentameric receptor superfamily provide touchstones for an emerging allosteric gating mechanism 7 . All available high-resolution structures are of homopentameric receptors.…”

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confidence: 99%

X-ray structure of the human α4β2 nicotinic receptor

Morales-Pérez

Noviello

Hibbs

2016

Nature

365

483

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Nicotinic acetylcholine receptors are ligand gated ion channels that mediate fast chemical neurotransmission at the neuromuscular junction and play diverse signaling roles in the central nervous system. The nicotinic receptor has been a model system for cell surface receptors, and specifically for ligand-gated ion channels, for well over a century1,2. In addition to the receptors’ prominent roles in the development of the fields of pharmacology and neurobiology, nicotinic receptors are important therapeutic targets for neuromuscular disease, addiction, epilepsy, and for neuromuscular blocking agents used during surgery2–4. The overall architecture of the receptor was described in landmark studies of the nicotinic receptor isolated from the electric organ of Torpedo marmorata5. Structures of a soluble ligand binding domain have provided atomic-scale insights into receptor-ligand interactions6, while high-resolution structures of other members of the pentameric receptor superfamily provide touchstones for an emerging allosteric gating mechanism7. All available high-resolution structures are of homopentameric receptors. However, the vast majority of pentameric receptors (called Cys-loop receptors in eukaryotes) present physiologically are heteromeric. Here we present the X-ray crystallographic structure of the human α4β2 nicotinic receptor, the most abundant nicotinic subtype in the brain. This structure provides insights into the architectural principles governing ligand recognition, heteromer assembly, ion permeation and desensitization in this prototypical receptor class.

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Emerging Molecular Mechanisms of Signal Transduction in Pentameric Ligand-Gated Ion Channels

Cited by 212 publications

References 205 publications

Allosteric binding site in a Cys-loop receptor ligand-binding domain unveiled in the crystal structure of ELIC in complex with chlorpromazine

Allosteric binding site in a Cys-loop receptor ligand-binding domain unveiled in the crystal structure of ELIC in complex with chlorpromazine

Residues Responsible for the Selectivity of α-Conotoxins for Ac-AChBP or nAChRs

X-ray structure of the human α4β2 nicotinic receptor

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