title: Packing of the extracellular domain hydrophobic core has evolved to facilitate pentameric ligand-gated ion channel function.
abstract: Protein function depends on conformational flexibility and folding stability. Loose packing of hydrophobic cores is not infrequent in proteins, as the enhanced flexibility likely contributes to their biological function. Here, using experimental and computational approaches, we show that eukaryotic pentameric ligand-gated ion channels are characterized by loose packing of their extracellular domain β-sandwich cores, and that loose packing contributes to their ability to rapidly switch from closed to open channel states in the presence of ligand. Functional analyses of GABA(A) receptors show that increasing the β-core packing disrupted GABA-mediated currents, with impaired GABA efficacy and slowed GABA current activation and desensitization. We propose that loose packing of the hydrophobic β-core developed as an evolutionary strategy aimed to facilitate the allosteric mechanisms of eukaryotic pentameric ligand-gated ion channels.
authors.affiliation: Department of Physiology, University of Wisconsin, Madison, Wisconsin 53711, USA.
authors.forename: Cosma D
authors.initials: CD
authors.lastname: Dellisanti
authors.forename: Sonya M
authors.initials: SM
authors.lastname: Hanson
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Cynthia
authors.initials: C
authors.lastname: Czajkowski
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D001048:Aplysia; D057927:Hydrophobic and Hydrophilic Interactions; D015640:Ion Channel Gating / Q000502:physiology*; D058446:Ligand-Gated Ion Channels / Q000737:chemistry*; D008195:Lymnaea; D056004:Molecular Dynamics Simulation; D017510:Protein Folding; D011963:Receptors, GABA-A / Q000737:chemistry*; D013816:Thermodynamics; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D058446:Ligand-Gated Ion Channels; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid