植物體內(nèi)的一種激素脫落酸可幫助植物對抗干旱等惡劣生存條件,，但科學(xué)界對這類植物激素的具體作用機(jī)制卻知之甚少,。西班牙等國研究人員日前發(fā)現(xiàn)脫落酸幫助植物抗旱的具體機(jī)制，為有效提高植物抗旱能力開辟了新思路,。
此前研究曾發(fā)現(xiàn),，在正常環(huán)境下，植物體內(nèi)一種名為PP2C的蛋白質(zhì)會阻止脫落酸發(fā)揮作用,，當(dāng)植物處于極度干旱條件下時,，這種阻斷作用就會消失，植物細(xì)胞中脫落酸的含量上升,，從而幫助植物抗旱,。研究同時認(rèn)為，PP2C蛋白質(zhì)并不會直接作用于脫落酸,，而是通過另外一群蛋白質(zhì)間接發(fā)揮作用,。這些“中介蛋白質(zhì)”究竟如何協(xié)調(diào)二者間的關(guān)系一直是科研人員的興趣所在,。
西班牙國家研究委員會和位于法國的歐洲分子生物學(xué)實(shí)驗室的研究人員在最近一期英國《自然》雜志上報告說，他們對這些“中介蛋白質(zhì)”中一種名為PYR1的蛋白質(zhì)進(jìn)行三維結(jié)構(gòu)分析后發(fā)現(xiàn),，這種蛋白質(zhì)如同一只手,，當(dāng)植物體內(nèi)的脫落酸含量少時，“手”處于張開狀態(tài),，允許PP2C蛋白質(zhì)阻止脫落酸發(fā)揮作用,。當(dāng)植物因環(huán)境刺激產(chǎn)生大量脫落酸時，這只“手”就會合攏,，緊緊握住脫落酸,，把PP2C蛋白質(zhì)阻擋在外，防止其影響脫落酸的作用,。
研究人員指出,，他們的研究再次確認(rèn)了上述“中介蛋白質(zhì)”是天然脫落酸的一類重要受體。了解其與脫落酸相互作用的具體機(jī)制,，就可以更有效地幫助植物具備更強(qiáng)的抗旱能力,。（生物谷Bioon.com）
植物抗旱研究：
PNAS：水稻抗旱性調(diào)控基因
Genes and Development：水稻抗逆功能基因研究
Sci. Signal.：發(fā)現(xiàn)水稻耐淹水的關(guān)鍵基因
生物谷推薦原始出處：
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.
