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.
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.
Kallen
Joerg A
JA
Central Technologies, Protein Structure Unit, Novartis Pharma AG, CH-4002 Basel, Switzerland. joerg.kallen@pharma.novartis.com
Schlaeppi
Jean-Marc
JM
Bitsch
Francis
F
Geisse
Sabine
S
Geiser
Martin
M
Delhon
Isabelle
I
Fournier
Brigitte
B
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
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