title: X-ray structures of AMPA receptor-cone snail toxin complexes illuminate activation mechanism.
abstract: AMPA-sensitive glutamate receptors are crucial to the structural and dynamic properties of the brain, to the development and function of the central nervous system, and to the treatment of neurological conditions from depression to cognitive impairment. However, the molecular principles underlying AMPA receptor activation have remained elusive. We determined multiple x-ray crystal structures of the GluA2 AMPA receptor in complex with a Conus striatus cone snail toxin, a positive allosteric modulator, and orthosteric agonists, at 3.8 to 4.1 angstrom resolution. We show how the toxin acts like a straightjacket on the ligand-binding domain (LBD) "gating ring," restraining the domains via both intra- and interdimer cross-links such that agonist-induced closure of the LBD "clamshells" is transduced into an irislike expansion of the gating ring. By structural analysis of activation-enhancing mutants, we show how the expansion of the LBD gating ring results in pulling forces on the M3 helices that, in turn, are coupled to ion channel gating.
authors.affiliation: Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
authors.forename: Katharina L
authors.initials: KL
authors.lastname: Dürr
authors.affiliation: Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA. Howard Hughes Medical Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA. gouauxe@ohsu.edu.
authors.forename: Eric
authors.initials: E
authors.lastname: Gouaux
mesh_terms: D000818:Animals; D020916:Conotoxins / Q000737:chemistry*; D052078:Conus Snail; D018360:Crystallography, X-Ray; D015640:Ion Channel Gating; D008024:Ligands; D009154:Mutation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D051381:Rats; D018091:Receptors, AMPA / Q000819:agonists* / Q000737:chemistry* / Q000235:genetics
chemical_list: D020916:Conotoxins; D008024:Ligands; D018091:Receptors, AMPA; C104722:glutamate receptor ionotropic, AMPA 2
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