abscisic acid receptor PYR1 in complex with abscisic acid

• Published in: Nature (London) 2009-12, Vol.462 (7273), p.665-668
• Main Authors: Santiago, Julia, Dupeux, Florine, Round, Adam, Antoni, Regina, Park, Sang-Youl, Jamin, Marc, Cutler, Sean R, Rodriguez, Pedro Luis, Marquez, Jose Antonio
• Format: Article
• Language: English
• Subjects: Abscisic acid; Abscisic Acid - metabolism; Agronomy. Soil science and plant productions; Arabidopsis; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; binding properties; binding proteins; binding sites; Biological and medical sciences; crystal structure; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Hardiness; Health aspects; Hormone receptors; Humanities and Social Sciences; letter; Membrane Transport Proteins - chemistry; Membrane Transport Proteins - metabolism; Models, Molecular; multidisciplinary; Physiological aspects; Plant cellular control mechanisms; Plant growth; Plants; Properties; Protein Binding; protein structure; Protein Structure, Tertiary; receptors; Science; Science (multidisciplinary); Water availability
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature08591

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.