| 19855379 |
Miyazono K, Miyakawa T, Sawano Y, Kubota K, Kang HJ, Asano A, Miyauchi Y, Takahashi M, Zhi Y, Fujita Y, Yoshida T, Kodaira KS, Yamaguchi-Shinozaki K, Tanokura M: Structural basis of abscisic acid signalling. Nature. 2009 Dec 3;462(7273):609-14.
The phytohormone abscisic acid (ABA) mediates the adaptation of plants to environmental stresses such as drought and regulates developmental signals such as seed maturation. Within plants, the PYR/PYL/RCAR family of START proteins receives ABA to inhibit the phosphatase activity of the group-A protein phosphatases 2C (PP2Cs), which are major negative regulators in ABA signalling. Here we present the crystal structures of the ABA receptor PYL1 bound with (+)-ABA, and the complex formed by the further binding of (+)-ABA-bound PYL1 with the PP2C protein ABI1. PYL1 binds (+)-ABA using the START-protein-specific ligand-binding site, thereby forming a hydrophobic pocket on the surface of the closed lid. (+)-ABA-bound PYL1 tightly interacts with a PP2C domain of ABI1 by using the hydrophobic pocket to cover the active site of ABI1 like a plug. Our results reveal the structural basis of the mechanism of (+)-ABA-dependent inhibition of ABI1 by PYL1 in ABA signalling. |
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