title: Structure of Liver Receptor Homolog-1 (NR5A2) with PIP3 hormone bound in the ligand binding pocket.
abstract: The nuclear receptor LRH-1 (Liver Receptor Homolog-1, NR5A2) is a transcription factor that regulates gene expression programs critical for many aspects of metabolism and reproduction. Although LRH-1 is able to bind phospholipids, it is still considered an orphan nuclear receptor (NR) with an unknown regulatory hormone. Our prior cellular and structural studies demonstrated that the signaling phosphatidylinositols PI(4,5)P2 (PIP2) and PI(3,4,5)P3 (PIP3) bind and regulate SF-1 (Steroidogenic Factor-1, NR5A1), a close homolog of LRH-1. Here, we describe the crystal structure of human LRH-1 ligand binding domain (LBD) bound by PIP3 - the first phospholipid with a head group endogenous to mammals. We show that the phospholipid hormone binds LRH-1 with high affinity, stabilizing the receptor LBD. While the hydrophobic PIP3 tails (C16/C16) are buried inside the LRH-1 ligand binding pocket, the negatively charged PIP3 head group is presented on the receptor surface, similar to the phosphatidylinositol binding mode observed in the PIP3-SF-1 structure. Thus, data presented in this work reinforce our earlier findings demonstrating that signaling phosphatidylinositols regulate the NR5A receptors LRH-1 and SF-1.
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, United States.
authors.forename: Elena P
authors.initials: EP
authors.lastname: Sablin
authors.affiliation: Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States.
authors.forename: Raymond D
authors.initials: RD
authors.lastname: Blind
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, United States.
authors.forename: Rubatharshini
authors.initials: R
authors.lastname: Uthayaruban
authors.affiliation: Joint Center for Structural Genomics, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States; Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States.
authors.forename: Hsiu-Ju
authors.initials: HJ
authors.lastname: Chiu
authors.affiliation: Joint Center for Structural Genomics, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States; Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States.
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Deacon
authors.affiliation: Joint Center for Structural Genomics, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States; Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States.
authors.forename: Debanu
authors.initials: D
authors.lastname: Das
authors.affiliation: Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, United States.
authors.forename: Holly A
authors.initials: HA
authors.lastname: Ingraham
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, United States. Electronic address: Robert.Fletterick@ucsf.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Fletterick
mesh_terms: D001665:Binding Sites / Q000502:physiology; D018360:Crystallography, X-Ray; D057137:DAX-1 Orphan Nuclear Receptor / Q000737:chemistry; D006801:Humans; D008958:Models, Molecular; D010716:Phosphatidylinositols / Q000737:chemistry*; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000648:ultrastructure*; D054339:Steroidogenic Factor 1 / Q000737:chemistry / Q000648:ultrastructure*
chemical_list: D057137:DAX-1 Orphan Nuclear Receptor; C539965:NR0B1 protein, human; C515057:NR5A1 protein, human; C082631:NR5A2 protein, human; D010716:Phosphatidylinositols; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1
keywords: Crystal structure; LRH-1; Ligand; Liver Receptor Homolog-1; NR5A2; Nuclear receptor; PIP(3)