A conformational intermediate in glutamate receptor activation.
Ionotropic glutamate receptors (iGluRs) transduce the chemical signal of neurotransmitter release into membrane depolarization at excitatory synapses in the brain. The opening of the transmembrane ion channel of these ligand-gated receptors is driven by conformational transitions that are induced by the association of glutamate molecules to the ligand-binding domains (LBDs). Here, we describe the crystal structure of a GluA2 LBD tetramer in a configuration that involves an ∼30° rotation of the LBD dimers relative to the crystal structure of the full-length receptor. The configuration is stabilized by an engineered disulfide crosslink. Biochemical and electrophysiological studies on full-length receptors incorporating either this crosslink or an engineered metal bridge show that this LBD configuration corresponds to an intermediate state of receptor activation. GluA2 activation therefore involves a combination of both intra-LBD (cleft closure) and inter-LBD dimer conformational transitions. Overall, these results provide a comprehensive structural characterization of an iGluR intermediate state.
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. alau@jhmi.edu
Albert Y
AY
Lau
Héctor
H
Salazar
Lydia
L
Blachowicz
Valentina
V
Ghisi
Andrew J R
AJ
Plested
Benoît
B
Roux
D001581:Benzothiadiazines / Q000494:pharmacology; D055592:Biophysical Phenomena / Q000187:drug effects / Q000235:genetics; D002461:Cell Line, Transformed; D018360:Crystallography, X-Ray / Q000379:methods; D003545:Cysteine / Q000235:genetics; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation / Q000235:genetics; D018408:Patch-Clamp Techniques; D010618:Phenanthrolines / Q000494:pharmacology; D017434:Protein Structure, Tertiary / Q000235:genetics; D011810:Quinoxalines / Q000494:pharmacology; D017470:Receptors, Glutamate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014475:Uncoupling Agents / Q000494:pharmacology
D001581:Benzothiadiazines; D018691:Excitatory Amino Acid Antagonists; D010618:Phenanthrolines; D011810:Quinoxalines; D017470:Receptors, Glutamate; D014475:Uncoupling Agents; C014741:bis(1,10-phenanthroline)copper(2+) ion; D018698:Glutamic Acid; C056723:FG 9041; D004228:Dithionitrobenzoic Acid; D003545:Cysteine; C004639:cyclothiazide