title: Dynamics of the Ligand Binding Domain Layer during AMPA Receptor Activation.
abstract: Ionotropic glutamate receptors are postsynaptic tetrameric ligand-gated channels whose activity mediates fast excitatory transmission. Glutamate binding to clamshell-shaped ligand binding domains (LBDs) triggers opening of the integral ion channel, but how the four LBDs orchestrate receptor activation is unknown. Here, we present a high-resolution x-ray crystal structure displaying two tetrameric LBD arrangements fully bound to glutamate. Using a series of engineered metal ion trapping mutants, we showed that the more compact of the two assemblies corresponds to an arrangement populated during activation of full-length receptors. State-dependent cross-linking of the mutants identified zinc bridges between the canonical active LBD dimers that formed when the tetramer was either fully or partially bound by glutamate. These bridges also stabilized the resting state, consistent with the recently published full-length apo structure. Our results provide insight into the activation mechanism of glutamate receptors and the complex conformational space that the LBD layer can sample.
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Jelena
authors.initials: J
authors.lastname: Baranovic
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Chebli
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Hector
authors.initials: H
authors.lastname: Salazar
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Carbone
authors.affiliation: Department of Crystallography, Max Delbrück Center for Molecular Medicine, Berlin, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Faelber
authors.affiliation: Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Albert Y
authors.initials: AY
authors.lastname: Lau
authors.affiliation: Department of Crystallography, Max Delbrück Center for Molecular Medicine, Berlin, Germany; Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Daumke
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Berlin, Germany. Electronic address: plested@fmp-berlin.de.
authors.forename: Andrew J R
authors.initials: AJ
authors.lastname: Plested
mesh_terms: D000818:Animals; D001059:Apoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D005971:Glutamates / Q000378:metabolism; D008024:Ligands; D008958:Models, Molecular; D009154:Mutation; D000072417:Protein Domains; D055503:Protein Multimerization; D051381:Rats; D018091:Receptors, AMPA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism
chemical_list: D001059:Apoproteins; D005971:Glutamates; D008024:Ligands; D018091:Receptors, AMPA; D015032:Zinc