Illuminating the activation mechanisms and allosteric properties of metabotropic glutamate receptors

• Published in: Proceedings of the National Academy of Sciences - PNAS 2013-04, Vol.110 (15), p.E1416-E1425
• Main Authors: Doumazane, Etienne, Scholler, Pauline, Fabre, Ludovic, Zwier, Jurriaan M., Trinquet, Eric, Pin, Jean-Philippe, Rondard, Philippe
• Format: Article
• Language: English
• Subjects: Allosteric Site; Animals; Binding sites; Biological Sciences; Calcium - metabolism; Cell Membrane - metabolism; Crystallography, X-Ray; DNA Mutational Analysis; Enzymes; Fluorescence Resonance Energy Transfer; Glutamic Acid - chemistry; GTP-Binding Proteins - metabolism; HEK293 Cells; Humans; Ligands; Molecular structure; Mutation; Plasmids - metabolism; PNAS Plus; PNAS PLUS: AUTHOR SUMMARIES; Protein Binding; Protein Conformation; Protein Interaction Domains and Motifs; Protein Multimerization; Proteins; Rats; Receptors, Metabotropic Glutamate - chemistry
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1215615110

In multimeric cell-surface receptors, the conformational changes of the extracellular ligand-binding domains (ECDs) associated with receptor activation remain largely unknown. This is the case for the dimeric metabotropic glutamate receptors even though a number of ECD structures have been solved. Here, using an innovative approach based on cell-surface labeling and FRET, we demonstrate that a reorientation of the ECDs is associated with receptor and G-protein activation. Our approach helps identify partial agonists and highlights allosteric interactions between the effector and binding domains. Any approach expected to stabilize the active conformation of the effector domain increased the agonist potency in stabilizing the active ECDs conformation. These data provide key information on the structural dynamics and drug action at metabotropic glutamate receptors and validate an approach for tackling such analysis on other receptors.