Posted by: shrikantmantri | October 27, 2009

Structural basis of abscisic acid signalling.

Nature. 2009 Oct 23. [Epub ahead of print]

Structural basis of abscisic acid signalling.

Miyazono KI, Miyakawa T, Sawano Y, Kubota K, Kang HJ, Asano A, Miyauchi Y, Takahashi M, Zhi Y, Fujita Y, Yoshida T, Kodaira K, Yamaguchi-Shinozaki K, Tanokura M.

[1] Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan [2] These authors contributed equally to this work.

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.

Posted via email from Sharing significant bytes —(Shrikant Mantri)

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