Structural basis for AMPA receptor activation and ligand selectivity: crystal structures of five agonist complexes with the GluR2 ligand-binding core

Research output: Contribution to journalJournal articleResearchpeer-review

A Hogner, Jette Sandholm Jensen Kastrup, R Jin, T Liljefors, M L Mayer, J Egebjerg, Ingrid K. Larsen, E Gouaux

Glutamate is the principal excitatory neurotransmitter within the mammalian CNS, playing an important role in many different functions in the brain such as learning and memory. In this study, a combination of molecular biology, X-ray structure determinations, as well as electrophysiology and binding experiments, has been used to increase our knowledge concerning the ionotropic glutamate receptor GluR2 at the molecular level. Five high-resolution X-ray structures of the ligand-binding domain of GluR2 (S1S2J) complexed with the three agonists (S)-2-amino-3-[3-hydroxy-5-(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl]propionic acid (2-Me-Tet-AMPA), (S)-2-amino-3-(3-carboxy-5-methylisoxazol-4-yl)propionic acid (ACPA), and (S)-2-amino-3-(4-bromo-3-hydroxy-isoxazol-5-yl)propionic acid (Br-HIBO), as well as of a mutant thereof (S1S2J-Y702F) in complex with ACPA and Br-HIBO, have been determined. The structures reveal that AMPA agonists with an isoxazole moiety adopt different binding modes in the receptor, dependent on the substituents of the isoxazole. Br-HIBO displays selectivity among different AMPA receptor subunits, and the design and structure determination of the S1S2J-Y702F mutant in complex with Br-HIBO and ACPA have allowed us to explain the molecular mechanism behind this selectivity and to identify key residues for ligand recognition. The agonists induce the same degree of domain closure as AMPA, except for Br-HIBO, which shows a slightly lower degree of domain closure. An excellent correlation between domain closure and efficacy has been obtained from electrophysiology experiments undertaken on non-desensitising GluR2i(Q)-L483Y receptors expressed in oocytes, providing strong evidence that receptor activation occurs as a result of domain closure. The structural results, combined with the functional studies on the full-length receptor, form a powerful platform for the design of new selective agonists.
Original languageEnglish
JournalJournal of Molecular Biology
Volume322
Issue number1
Pages (from-to)93-109
Number of pages17
ISSN0022-2836
Publication statusPublished - 6 Sep 2002

    Research areas

  • Animals, Binding Sites, Crystallography, X-Ray, Electrophysiology, Hydrogen Bonding, Ion Channel Gating, Ion Channels, Ligands, Models, Molecular, Molecular Structure, Movement, Mutation, Oocytes, Protein Structure, Quaternary, Protein Structure, Tertiary, Protein Subunits, Receptors, AMPA, Static Electricity, Structure-Activity Relationship, Substrate Specificity

ID: 44729560