清華大學兼職教授顏寧博士以及王佳偉副研究員領導的研究組于11月5日在Nature Structural & Molecular Biology上發(fā)表學術論文“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脫落酸信號傳導的分子機制,。
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、抗旱反應和其它的生理過程都有極為密切的關系,。由于脫落酸能引發(fā)的下游反應過多,，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信號的調(diào)控，因此從ABA被發(fā)現(xiàn)半個世紀以來一直不清楚ABA的受體是什么,。過去幾年陸續(xù)有一些關于ABA受體的發(fā)現(xiàn)報導,，但其具體功能尚有所爭議。今年四月底,，Science發(fā)表兩個獨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)外結合ABA,，之后會結合下游的蛋白磷酸酶PP2C并抑制其磷酸酶活性,，然而其中的分子機制尚不清楚。并且由于之前關于ABA受體的諸多爭議,，PYL蛋白是否為真正的ABA受體也還有待進一步驗證,。在這種背景下，結構生物學研究變得至關重要,。
顏寧教授的研究組自2007年建立之初就開始了對于ABA受體的結構生物學研究,。此次，在醫(yī)學院顏寧教授和生命學院王佳偉博士的指導下,，由生命學院和醫(yī)學院的博士后及研究生聯(lián)手歷時四個月完成的研究成果報道了PYL蛋白在1）沒有ABA,，2）結合ABA，以及3）同時結合ABA和下游PP2C的三個狀態(tài)下的高分辨率分子結構,。通過結構比較和生化分析,，確認PYL蛋白為ABA受體,，并且發(fā)現(xiàn)其中一個被命名為CL2的蛋白柔性區(qū)在介導ABA信號及抑制PP2C活性中起了至關重要的作用。（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.
