植物体内的一种激素脱落酸可帮助植物对抗干旱等恶劣生存条件，但科学界对这类植物激素的具体作用机制却知之甚少。西班牙等国研究人员日前发现脱落酸帮助植物抗旱的具体机制，为有效提高植物抗旱能力开辟了新思路。
此前研究曾发现，在正常环境下，植物体内一种名为PP2C的蛋白质会阻止脱落酸发挥作用，当植物处于极度干旱条件下时，这种阻断作用就会消失，植物细胞中脱落酸的含量上升，从而帮助植物抗旱。研究同时认为，PP2C蛋白质并不会直接作用于脱落酸，而是通过另外一群蛋白质间接发挥作用。这些“中介蛋白质”究竟如何协调二者间的关系一直是科研人员的兴趣所在。
西班牙国家研究委员会和位于法国的欧洲分子生物学实验室的研究人员在最近一期英国《自然》杂志上报告说，他们对这些“中介蛋白质”中一种名为PYR1的蛋白质进行三维结构分析后发现，这种蛋白质如同一只手，当植物体内的脱落酸含量少时，“手”处于张开状态，允许PP2C蛋白质阻止脱落酸发挥作用。当植物因环境刺激产生大量脱落酸时，这只“手”就会合拢，紧紧握住脱落酸，把PP2C蛋白质阻挡在外，防止其影响脱落酸的作用。
研究人员指出，他们的研究再次确认了上述“中介蛋白质”是天然脱落酸的一类重要受体。了解其与脱落酸相互作用的具体机制，就可以更有效地帮助植物具备更强的抗旱能力。（生物谷Bioon.com）
植物抗旱研究：
PNAS：水稻抗旱性调控基因
Genes and Development：水稻抗逆功能基因研究
Sci. Signal.：发现水稻耐淹水的关键基因
生物谷推荐原始出处：
Nature 8 November 2009 | doi:10.1038/nature08591
The abscisic acid receptor PYR1 in complex with abscisic acid
Julia Santiago1,5, Florine Dupeux2,5, Adam Round2, Regina Antoni1, Sang-Youl Park3, Marc Jamin4, Sean R. Cutler3, Pedro Luis Rodriguez1 & José Antonio Márquez2
1 Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, ES-46022 Valencia, Spain
2 European Molecular Biology Laboratory, Grenoble Outstation and Unit of Virus Host-Cell Interactions, UJF-EMBL-CNRS, 6 rue Jules Horowitz, BP181, 38042 Grenoble Cedex 9, France
3 Department of Botany and Plant Sciences. Center for Plant Cell Biology. University of California, Riverside, California 92521, USA
4 Virus Host Cell Interactions (UVHCI) UMI 3265, Université Joseph Fourier-EMBL-CNRS, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France
5 These authors contributed equally to this work.
Correspondence to: José Antonio Márquez2 Correspondence and requests for materials should be addressed to J.A.M.
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/RCAR1, 2, 3, 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)4, 5, 6. 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.
