The Serotonin Binding Site of Human and Murine 5-HT2BReceptors

Philippe Manivet (1, 2, 3) , Benoı̂t Schneider (4) , Jeremy Christopher Smith (5) , Doo-Sup Choi (6) , Luc Maroteaux (6) , Odile Kellermann (4) , Jean-Marie Launay (1, 2)

1 Hôpital Lariboisière-Fernand-Widal [APHP]
2 IFR6 - Service Biochimie et Biologie Moleculaire [AP-HP Hôpital Lariboisière]
3 DCMR - Laboratoire des mécanismes réactionnels
4 UMS33 Inserm/IAL - Unité mixte de service UMS33 [Institut André Lwoff]
5 Universität Heidelberg [Heidelberg] = Heidelberg University
6 IGBMC - Institut de génétique et biologie moléculaire et cellulaire

Bacteriorhodopsin and rhodopsin crystal structures were used as templates to build structural models of the mouse and human serotonin (5-HT)-2B receptors (5-HT(2B)Rs). Serotonin was docked to the receptors, and the amino acids predicted to participate to its binding were subjected to mutagenesis. 5-HT binding affinity and 5-HT-induced inositol triphosphate production were measured in LMTK(-) cells transfected with either wild-type or mutated receptor genes. According to these measurements, the bacteriorhodopsin-based models of the 5-HT(2B)Rs appear more confident than the rhodopsin-based ones. Residues belonging to the transmembrane domains 3 and 6, i.e. Asp(3.32), Ser(3.36), Phe(6.52), and Asn(6.55), make direct contacts with 5-HT. In addition, Trp(3.28), Phe(3.35), Phe(6.52), and Phe(7.38) form an aromatic box surrounding 5-HT. The specificity of human and mouse 5-HT(2B)Rs may be reflected by different rearrangements of the aromatic network upon 5-HT binding. Two amino acids close to Pro(5.50) in the human transmembrane domain 5 sequence were permuted to introduce a "mouse-like" sequence. This change was enough to confer the human 5-HT(2B)R properties similar to those of the mouse. Taken together, the computed models and the site-directed mutagenesis experiments give a structural explanation to (i) the different 5-HT pK(D) values measured with the human and mouse 5-HT(2B)Rs (7.9 and 5.8, respectively) and (ii) the specificity of 5-HT binding to 5-HT(2B)Rs as compared with other serotonergic G-protein coupled receptors.

Domaines: Biochimie, Biologie Moléculaire

Philippe Manivet, Benoı̂t Schneider, Jeremy Christopher Smith, Doo-Sup Choi, Luc Maroteaux, et al.. The Serotonin Binding Site of Human and Murine 5-HT2BReceptors. Journal of Biological Chemistry, 2002, 277 (19), pp.17170-17178. ⟨10.1074/jbc.M200195200⟩. ⟨hal-04150738⟩