title: Bioluminescence resonance energy transfer reveals ligand-induced conformational changes in CXCR4 homo- and heterodimers.
abstract: Homo- and heterodimerization have emerged as prominent features of G-protein-coupled receptors with possible impact on the regulation of their activity. Using a sensitive bioluminescence resonance energy transfer system, we investigated the formation of CXCR4 and CCR2 chemokine receptor dimers. We found that both receptors exist as constitutive homo- and heterodimers and that ligands induce conformational changes within the pre-formed dimers without promoting receptor dimer formation or disassembly. Ligands with different intrinsic efficacies yielded distinct bioluminescence resonance energy transfer modulations, indicating the stabilization of distinct receptor conformations. We also found that peptides derived from the transmembrane domains of CXCR4 inhibited activation of this receptor by blocking the ligand-induced conformational transitions of the dimer. Taken together, our data support a model in which chemokine receptor homo- and heterodimers form spontaneously and respond to ligand binding as units that undergo conformational changes involving both protomers even when only one of the two ligand binding sites is occupied.
authors.affiliation: Department of Biochemistry, Université de Montréal, Montréal H3C 3J7, Québéc, Canada.
authors.forename: Yann
authors.initials: Y
authors.lastname: Percherancier
authors.forename: Yamina A
authors.initials: YA
authors.lastname: Berchiche
authors.forename: Isabelle
authors.initials: I
authors.lastname: Slight
authors.forename: Rudolf
authors.initials: R
authors.lastname: Volkmer-Engert
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tamamura
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Fujii
authors.forename: Michel
authors.initials: M
authors.lastname: Bouvier
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Heveker
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001665:Binding Sites; D002460:Cell Line; D018932:Chemokine CCL2 / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D006801:Humans; D007700:Kinetics; D008024:Ligands; D008164:Luminescent Proteins / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D019718:Receptors, CXCR4 / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors; D014162:Transfection
chemical_list: D001426:Bacterial Proteins; C111835:CCL2 protein, human; D018932:Chemokine CCL2; D008024:Ligands; D008164:Luminescent Proteins; D010455:Peptides; D019718:Receptors, CXCR4; C054562:yellow fluorescent protein, Bacteria; D000242:Cyclic AMP