清華大學(xué)兼職教授顏寧博士以及王佳偉副研究員領(lǐng)導(dǎo)的研究組于11月5日在Nature Structural & Molecular Biology上發(fā)表學(xué)術(shù)論文“Structural Insights into the mechanism of Abscisic acid signaling by PYL proteins”,，系統(tǒng)闡述了脫落酸受體介導(dǎo)脫落酸信號(hào)傳導(dǎo)的分子機(jī)制,。
脫落酸（Abscisic acid, ABA）是植物中最為重要的激素之一,，它與種子休眠,、根系發(fā)育,、葉子枯萎、抗旱反應(yīng)和其它的生理過程都有極為密切的關(guān)系,。由于脫落酸能引發(fā)的下游反應(yīng)過多,，包括激酶、磷酸酶,、G蛋白,、泛素通路中的蛋白等等都參與了ABA信號(hào)的調(diào)控，因此從ABA被發(fā)現(xiàn)半個(gè)世紀(jì)以來一直不清楚ABA的受體是什么,。過去幾年陸續(xù)有一些關(guān)于ABA受體的發(fā)現(xiàn)報(bào)導(dǎo),，但其具體功能尚有所爭(zhēng)議。今年四月底,，Science發(fā)表兩個(gè)獨(dú)立研究組的最新成果,，發(fā)現(xiàn)一類被命名為PYR/PYL或是RCAR的蛋白為ABA受體。這類蛋白可以在體內(nèi)外結(jié)合ABA,，之后會(huì)結(jié)合下游的蛋白磷酸酶PP2C并抑制其磷酸酶活性,，然而其中的分子機(jī)制尚不清楚。并且由于之前關(guān)于ABA受體的諸多爭(zhēng)議,，PYL蛋白是否為真正的ABA受體也還有待進(jìn)一步驗(yàn)證,。在這種背景下，結(jié)構(gòu)生物學(xué)研究變得至關(guān)重要,。
顏寧教授的研究組自2007年建立之初就開始了對(duì)于ABA受體的結(jié)構(gòu)生物學(xué)研究,。此次，在醫(yī)學(xué)院顏寧教授和生命學(xué)院王佳偉博士的指導(dǎo)下,，由生命學(xué)院和醫(yī)學(xué)院的博士后及研究生聯(lián)手歷時(shí)四個(gè)月完成的研究成果報(bào)道了PYL蛋白在1）沒有ABA,，2）結(jié)合ABA，以及3）同時(shí)結(jié)合ABA和下游PP2C的三個(gè)狀態(tài)下的高分辨率分子結(jié)構(gòu),。通過結(jié)構(gòu)比較和生化分析,，確認(rèn)PYL蛋白為ABA受體，并且發(fā)現(xiàn)其中一個(gè)被命名為CL2的蛋白柔性區(qū)在介導(dǎo)ABA信號(hào)及抑制PP2C活性中起了至關(guān)重要的作用,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature Structural & Molecular Biology 5 November 2009 | doi:10.1038/nsmb.1730
Structural insights into the mechanism of abscisic acid signaling by PYL proteins
Ping Yin1,2,4, He Fan1,2,4, Qi Hao1,3,4, Xiaoqiu Yuan1,3,4, Di Wu1,2, Yuxuan Pang1,2, Chuangye Yan1,2, Wenqi Li1,3, Jiawei Wang1,2 & Nieng Yan1,3
Abstract
Abscisic acid (ABA) is an important phytohormone that regulates plant stress responses. Proteins from the PYR-PYL-RCAR family were recently identified as ABA receptors. Upon binding to ABA, a PYL protein associates with type 2C protein phosphatases (PP2Cs) such as ABI1 and ABI2, inhibiting their activity; the molecular mechanisms by which PYLs mediate ABA signaling remain unknown, however. Here we report three crystal structures: apo-PYL2, (+)-ABA-bound PYL2 and (+)-ABA-bound PYL1 in complex with phosphatase ABI1. Apo-PYL2 contains a pocket surrounded by four highly conserved surface loops. In response to ABA binding, loop CL2 closes onto the pocket, creating a surface that recognizes ABI1. In the ternary complex, the CL2 loop is located near the active site of ABI1, blocking the entry of substrate proteins. Together, our data reveal the mechanisms by which ABA regulates PYL-mediated inhibition of PP2Cs.
1 State Key Laboratory of Bio-membrane and Membrane Biotechnology
2 Center for Structural Biology, School of Life Sciences
3 School of Medicine, Tsinghua University, Beijing, China.
4 These authors contributed equally to this work.
