Identification of a pre-active conformation of a pentameric channel receptor.

TitleIdentification of a pre-active conformation of a pentameric channel receptor.
Publication TypeJournal Article
Year of Publication2017
AuthorsMenny A, Lefebvre SN, Schmidpeter PAm, Drège E, Fourati Z, Delarue M, Edelstein SJ, Nimigean CM, Joseph D, Corringer P-J
Date Published2017 03 15
KeywordsAnimals, Bacterial Proteins, Bridged Bicyclo Compounds, Heterocyclic, Cloning, Molecular, Cyanobacteria, Escherichia coli, Fluorescent Dyes, Gene Expression, Hydrogen-Ion Concentration, Kinetics, Ligand-Gated Ion Channels, Membrane Potentials, Models, Molecular, Mutation, Oocytes, Patch-Clamp Techniques, Protein Binding, Protein Conformation, alpha-Helical, Protein Conformation, beta-Strand, Protein Interaction Domains and Motifs, Protein Multimerization, Protein Structure, Tertiary, Recombinant Proteins, Staining and Labeling, Xenopus laevis

Pentameric ligand-gated ion channels (pLGICs) mediate fast chemical signaling through global allosteric transitions. Despite the existence of several high-resolution structures of pLGICs, their dynamical properties remain elusive. Using the proton-gated channel GLIC, we engineered multiple fluorescent reporters, each incorporating a bimane and a tryptophan/tyrosine, whose close distance causes fluorescence quenching. We show that proton application causes a global compaction of the extracellular subunit interface, coupled to an outward motion of the M2-M3 loop near the channel gate. These movements are highly similar in lipid vesicles and detergent micelles. These reorganizations are essentially completed within 2 ms and occur without channel opening at low proton concentration, indicating that they report a pre-active intermediate state in the transition pathway toward activation. This provides a template to investigate the gating of eukaryotic neurotransmitter receptors, for which intermediate states also participate in activation.

Alternate JournalElife
PubMed ID28294942
PubMed Central IDPMC5398890
Grant ListR01 GM021342 / GM / NIGMS NIH HHS / United States
R01 GM088352 / GM / NIGMS NIH HHS / United States