5119 Structural basis for glucocorticoid receptor multimerization

Abstract Disclosure: E. Estébanez-Perpiñá: None. Abstract ENDO-2024 - BostonStructural basis for glucocorticoid receptor multimerization Andrea Alegre-Martí[1]*, Alba Jimenez-Panizo2*, Agustina Lafuente3, Montserrat Abella[1], Thomas A Johnson2, Paloma Pérez4, Juan Fernández-Recio5, Diego M. Presman3, Gordon L. Hager2, Pablo Fuentes-Prior[1], Eva Estébanez-Perpiñá[1] [1]Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine of the University of Barcelona (IBUB), Faculty of Biology, University of Barcelona (UB), 08028 Barcelona, Spain.2National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-5055, USA.3IFIBYNE, UBA-CONICET, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, C1428EGA, Argentina.4Instituto de Biomedicina de Valencia (IBV)-CSIC, 46010, Valencia, Spain.5Instituto de Ciencias de la Vid y del Vino (ICVV), CSIC - Universidad de La Rioja - Gobierno de La Rioja, 26007 Logroño, Spain. Abstract: The glucocorticoid receptor (GR) is a ubiquitously e2xpressed ligand-regulated transcription factor essential for life and one of the most targeted proteins in drug discovery due to its powerful anti-inflammatory actions. The functional oligomeric state of the full-length receptor, which is essential for its transcriptional activity in cells, remains disputed. Here we present a new crystal structure of agonist-bound ancient GR-LBD in a large cell, along with a thorough analysis of previous structural work. The building block of the current structure is a homodimer we previously identified in GR-LBD crystals and its biological relevance has been verified by studying a battery of GR point mutants including crosslinking assays in solution and quantitative fluorescence microscopy in live cells. Several mutually exclusive multimeric assemblies of this dimer in the crystal highlight the versatility of GR-LBD for self-association and reveal implications for the conformation of the active full-length receptor. Our results underscore the relevance of non-canonical dimerization modes for GR-LBD, especially of contacts made by key residues such as Tyr545, Pro637 and Asp641. Of note, a non-conservative mutation of the latter, p.Asp641Val, causes Chrousos syndrome in humans. Understanding relevant quaternary assemblies of the GR is pivotal not only to understand and predict the therapeutic outcome of major blockbuster drugs but also to lessen their deleterious side effects and open new avenues for drug design. Presentation: 6/3/2024