Ligand Binding Induces Conformational Changes in Human Cellular Retinol-binding Protein 1 (CRBP1) Revealed by Atomic Resolution Crystal Structures.Silvaroli, J.A., Arne, J.M., Chelstowska, S., Kiser, P.D., Banerjee, S., Golczak, M.
(2016) J.Biol.Chem. 291: 8528-8540
- PubMed: 26900151
- DOI: 10.1074/jbc.M116.714535
- Primary Citation of Related Structures:
- PubMed Abstract:
Important in regulating the uptake, storage, and metabolism of retinoids, cellular retinol-binding protein 1 (CRBP1) is essential for trafficking vitamin A through the cytoplasm. However, the molecular details of ligand uptake and targeted release by ...
Important in regulating the uptake, storage, and metabolism of retinoids, cellular retinol-binding protein 1 (CRBP1) is essential for trafficking vitamin A through the cytoplasm. However, the molecular details of ligand uptake and targeted release by CRBP1 remain unclear. Here we report the first structure of CRBP1 in a ligand-free form as well as ultra-high resolution structures of this protein bound to either all-trans-retinol or retinylamine, the latter a therapeutic retinoid that prevents light-induced retinal degeneration. Superpositioning of human apo- and holo-CRBP1 revealed major differences within segments surrounding the entrance to the retinoid-binding site. These included α-helix II and hairpin turns between β-strands βC-βD and βE-βF as well as several side chains, such as Phe-57, Tyr-60, and Ile-77, that change their orientations to accommodate the ligand. Additionally, we mapped hydrogen bond networks inside the retinoid-binding cavity and demonstrated their significance for the ligand affinity. Analyses of the crystallographic B-factors indicated several regions with higher backbone mobility in the apoprotein that became more rigid upon retinoid binding. This conformational flexibility of human apo-CRBP1 facilitates interaction with the ligands, whereas the more rigid holoprotein structure protects the labile retinoid moiety during vitamin A transport. These findings suggest a mechanism of induced fit upon ligand binding by mammalian cellular retinol-binding proteins.
From the Department of Pharmacology and.,From the Department of Pharmacology and the Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, email@example.com.,From the Department of Pharmacology and the Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106.,the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, and the Northeastern Collaborative Access Team, Argonne National Laboratory, Argonne, Illinois 60439.,From the Department of Pharmacology and the Laboratory of Hematology and Flow Cytometry, Department of Hematology, Military Institute of Medicine, Warsaw 04-141, Poland.