title: X-ray structure of the hRORalpha LBD at 1.63 A: structural and functional data that cholesterol or a cholesterol derivative is the natural ligand of RORalpha.
abstract: The retinoic acid-related orphan receptor alpha (RORalpha) is an orphan member of the subfamily 1 of nuclear hormone receptors. No X-ray structure of RORalpha has been described so far, and no ligand has been identified. We describe the first crystal structure of the ligand binding domain (LBD) of RORalpha, at 1.63 A resolution. This structure revealed a ligand present in the ligand binding pocket (LBP), which was identified by X-ray crystallography as cholest-5-en-3beta-ol (cholesterol). Moreover, RORalpha transcriptional activity could be modulated by changes in intracellular cholesterol level or mutation of residues involved in cholesterol binding. These findings suggest that RORalpha could play a key role in the regulation of cholesterol homeostasis and thus represents an important drug target in cholesterol-related diseases.
authors.affiliation: Central Technologies, Protein Structure Unit, Novartis Pharma AG, CH-4002 Basel, Switzerland. joerg.kallen@pharma.novartis.com
authors.forename: Joerg A
authors.initials: JA
authors.lastname: Kallen
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Schlaeppi
authors.forename: Francis
authors.initials: F
authors.lastname: Bitsch
authors.forename: Sabine
authors.initials: S
authors.lastname: Geisse
authors.forename: Martin
authors.initials: M
authors.lastname: Geiser
authors.forename: Isabelle
authors.initials: I
authors.lastname: Delhon
authors.forename: Brigitte
authors.initials: B
authors.lastname: Fournier
mesh_terms: D002784:Cholesterol / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D008024:Ligands; D008148:Lovastatin / Q000494:pharmacology; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1; D011487:Protein Conformation; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D021241:Spectrometry, Mass, Electrospray Ionization; D015534:Trans-Activators / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D014407:Tumor Cells, Cultured
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D008024:Ligands; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1; C539738:RORA protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D015534:Trans-Activators; D002784:Cholesterol; D008148:Lovastatin