title: Molecular recognition of corticotropin-releasing factor by its G-protein-coupled receptor CRFR1.
abstract: The bimolecular interaction between corticotropin-releasing factor (CRF), a neuropeptide, and its type 1 receptor (CRFR1), a class B G-protein-coupled receptor (GPCR), is crucial for activation of the hypothalamic-pituitary-adrenal axis in response to stress, and has been a target of intense drug design for the treatment of anxiety, depression, and related disorders. As a class B GPCR, CRFR1 contains an N-terminal extracellular domain (ECD) that provides the primary ligand binding determinants. Here we present three crystal structures of the human CRFR1 ECD, one in a ligand-free form and two in distinct CRF-bound states. The CRFR1 ECD adopts the alpha-beta-betaalpha fold observed for other class B GPCR ECDs, but the N-terminal alpha-helix is significantly shorter and does not contact CRF. CRF adopts a continuous alpha-helix that docks in a hydrophobic surface of the ECD that is distinct from the peptide-binding site of other class B GPCRs, thereby providing a basis for the specificity of ligand recognition between CRFR1 and other class B GPCRs. The binding of CRF is accompanied by clamp-like conformational changes of two loops of the receptor that anchor the CRF C terminus, including the C-terminal amide group. These structural studies provide a molecular framework for understanding peptide binding and specificity by the CRF receptors as well as a template for designing potent and selective CRFR1 antagonists for therapeutic applications.
authors.affiliation: Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan 49503, USA. augie.pioszak@vai.org
authors.forename: Augen A
authors.initials: AA
authors.lastname: Pioszak
authors.forename: Naomi R
authors.initials: NR
authors.lastname: Parker
authors.forename: Kelly
authors.initials: K
authors.lastname: Suino-Powell
authors.forename: H Eric
authors.initials: HE
authors.lastname: Xu
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006801:Humans; D008024:Ligands; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D008024:Ligands; D010455:Peptides; D018019:Receptors, Corticotropin-Releasing Hormone; D043562:Receptors, G-Protein-Coupled; D003346:Corticotropin-Releasing Hormone
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