title: Novel selective allosteric and bitopic ligands for the S1P(3) receptor.
abstract: Sphingosine 1-phosphate (S1P) is a lysophospholipid signaling molecule that regulates important biological functions, including lymphocyte trafficking and vascular development, by activating G protein-coupled receptors for S1P, namely, S1P(1) through S1P(5). Here, we map the S1P(3) binding pocket with a novel allosteric agonist (CYM-5541), an orthosteric agonist (S1P), and a novel bitopic antagonist (SPM-242). With a combination of site-directed mutagenesis, ligand competition assay, and molecular modeling, we concluded that S1P and CYM-5541 occupy different chemical spaces in the ligand binding pocket of S1P(3). CYM-5541 allowed us to identify an allosteric site where Phe263 is a key gate-keeper residue for its affinity and efficacy. This ligand lacks a polar moiety, and the novel allosteric hydrophobic pocket permits S1P(3) selectivity of CYM-5541 within the highly similar S1P receptor family. However, a novel S1P(3)-selective antagonist, SPM-242, in the S1P(3) pocket occupies the ligand binding spaces of both S1P and CYM-5541, showing its bitopic mode of binding. Therefore, our coordinated approach with biochemical data and molecular modeling, based on our recently published S1P(1) crystal structure data in a highly conserved set of related receptors with a shared ligand, provides a strong basis for the successful optimization of orthosteric, allosteric, and bitopic modulators of S1P(3).
authors.affiliation: Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Euijung
authors.initials: E
authors.lastname: Jo
authors.forename: Barun
authors.initials: B
authors.lastname: Bhhatarai
authors.forename: Emanuela
authors.initials: E
authors.lastname: Repetto
authors.forename: Miguel
authors.initials: M
authors.lastname: Guerrero
authors.forename: Sean
authors.initials: S
authors.lastname: Riley
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Brown
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kohno
authors.forename: Edward
authors.initials: E
authors.lastname: Roberts
authors.forename: Stephan C
authors.initials: SC
authors.lastname: Schürer
authors.forename: Hugh
authors.initials: H
authors.lastname: Rosen
mesh_terms: D000495:Allosteric Site; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D008024:Ligands; D008958:Models, Molecular; D010766:Phosphorylation; D011869:Radioligand Assay; D049349:Receptors, Lysosphingolipid / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D008024:Ligands; D049349:Receptors, Lysosphingolipid