4k6i
Crystal structure of human retinoid X receptor alpha-ligand binding domain complex with Targretin and the coactivator peptide GRIP-1
Structural highlights
FunctionRXRA_HUMAN Receptor for retinoic acid. Retinoic acid receptors bind as heterodimers to their target response elements in response to their ligands, all-trans or 9-cis retinoic acid, and regulate gene expression in various biological processes. The RAR/RXR heterodimers bind to the retinoic acid response elements (RARE) composed of tandem 5'-AGGTCA-3' sites known as DR1-DR5. The high affinity ligand for RXRs is 9-cis retinoic acid. RXRA serves as a common heterodimeric partner for a number of nuclear receptors. The RXR/RAR heterodimers bind to the retinoic acid response elements (RARE) composed of tandem 5'-AGGTCA-3' sites known as DR1-DR5. In the absence of ligand, the RXR-RAR heterodimers associate with a multiprotein complex containing transcription corepressors that induce histone acetylation, chromatin condensation and transcriptional suppression. On ligand binding, the corepressors dissociate from the receptors and associate with the coactivators leading to transcriptional activation. The RXRA/PPARA heterodimer is required for PPARA transcriptional activity on fatty acid oxidation genes such as ACOX1 and the P450 system genes.[1] [2] [3] [4] Publication Abstract from PubMedRetinoid X Receptors (RXRs) are obligate partners for several other nuclear receptors, and they play a key role in several signaling processes. Despite being a promiscuous heterodimer partner, this nuclear receptor is a target of therapeutic intervention through activation using selective RXR-agonists (rexinoids). Agonist binding to RXR initiates a large conformational change in the receptor which allows for coactivator recruitment to its surface and enhanced transcription. Here we reveal the structural and dynamical changes produced when a coactivator peptide binds to the human RXR-alpha ligand binding domain containing two clinically relevant rexinoids, Targretin and 9-cis-UAB30. Our results show the structural changes are very similar for each rexinoid and similar to those for the pan-agonist 9-cis-retinoic acid. The four structural changes involve key residues on helix 3, helix 4, and helix 11 that move from a solvent exposed environment to one that interacts extensively with helix 12. Hydrogen-deuterium exchange mass spectrometry (HDX MS) reveals the dynamics of helices 3, 11 and 12 are significantly decreased when the two rexinoids are bound to the receptor. When the pan-agonist 9-cis-retinoic acid is bound to the receptor, only the dynamics of helices 3 and 11 are reduced. The four structural changes are conserved in all x-ray structures of the RXR ligand binding domain in the presence of agonist and coactivator peptide. They serve as hallmarks for how RXR changes conformation and dynamics in the presence of agonist and coactivator to initiate signaling. Defining the communication between agonist and coactivator binding in the retinoid X receptor ligand binding domain.,Boerma LJ, Xia G, Qui C, Cox BD, Chalmers MJ, Smith CD, Lobo-Ruppert S, Griffin P, Muccio DD, Renfrow MB J Biol Chem. 2013 Nov 1. PMID:24187139[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
| ||||||||||||||||||||
