title: The abscisic acid receptor PYR1 in complex with abscisic acid.
abstract: The plant hormone abscisic acid (ABA) has a central role in coordinating the adaptive response in situations of decreased water availability as well as the regulation of plant growth and development. Recently, a 14-member family of intracellular ABA receptors, named PYR/PYL/RCAR, has been identified. These proteins inhibit in an ABA-dependent manner the activity of a family of key negative regulators of the ABA signalling pathway: the group-A protein phosphatases type 2C (PP2Cs). Here we present the crystal structure of Arabidopsis thaliana PYR1, which consists of a dimer in which one of the subunits is bound to ABA. In the ligand-bound subunit, the loops surrounding the entry to the binding cavity fold over the ABA molecule, enclosing it inside, whereas in the empty subunit they form a channel leaving an open access to the cavity, indicating that conformational changes in these loops have a critical role in the stabilization of the hormone-receptor complex. By providing structural details on the ABA-binding pocket, this work paves the way for the development of new small molecules able to activate the plant stress response.
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, ES-46022 Valencia, Spain.
authors.forename: Julia
authors.initials: J
authors.lastname: Santiago
authors.forename: Florine
authors.initials: F
authors.lastname: Dupeux
authors.forename: Adam
authors.initials: A
authors.lastname: Round
authors.forename: Regina
authors.initials: R
authors.lastname: Antoni
authors.forename: Sang-Youl
authors.initials: SY
authors.lastname: Park
authors.forename: Marc
authors.initials: M
authors.lastname: Jamin
authors.forename: Sean R
authors.initials: SR
authors.lastname: Cutler
authors.forename: Pedro Luis
authors.initials: PL
authors.lastname: Rodriguez
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Márquez
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; C540976:AT4G17870 protein, Arabidopsis; D000040:Abscisic Acid