脱落酸（ABA）是一种主要植物激素，其作用是保护植物不受干旱和低温等压力影响，并且在气孔打开和种子休眠等日常响应中发挥作用。在ABA通道中作为受体而引人注目的是PYR/PYL/RCAR家族的蛋白以及2-型磷酸酶ABI1、ABI2 和PP2C，它们抑制ABA信号作用。
现在，三个小组报告了ABA在非结合状态及在包括PYL2-ABA-PP2C和PYL1-ABA-ABI1在内的不同复合物中的晶体结构。这些结构表明，PYL/ABA生成一个与PP2C 和ABI1相结合的疏水穴，同时结合生化研究，这些结构还为ABA信号作用指出了一个机制（Articles pp. 602, 609; Letter p. 665）。Jian-Kang Zhu及其同事在试管中重构了ABA信号通道（这对植物激素来说是第一次），并在活体中对关键观测结果进行了验证。（生物谷Bioon.com）
更多脱落酸研究：
NSMB：脱落酸受体介导脱落酸信号传导的分子机制
Cell：发现两种新型脱落酸受体
Nature：蛋白质PYR1调节植物抗旱机制
Science：确认新的ABA受体
《自然》准备撤销高被引植物学论文
生物谷推荐原始出处：
Nature 462, 602-608 (3 December 2009) | doi:10.1038/nature08613
A gate–latch–lock mechanism for hormone signalling by abscisic acid receptors near-final version
Karsten Melcher1,7, Ley-Moy Ng1,2,7, X. Edward Zhou1,7, Fen-Fen Soon1,2,7, Yong Xu1, Kelly M. Suino-Powell1, Sang-Youl Park3, Joshua J. Weiner4, Hiroaki Fujii3,5, Viswanathan Chinnusamy3,5, Amanda Kovach1, Jun Li1,2, Yonghong Wang6, Jiayang Li6, Francis C. Peterson4, Davin R. Jensen4, Eu-Leong Yong2, Brian F. Volkman4, Sean R. Cutler3, Jian-Kang Zhu3,5 & H. Eric Xu1
1 Laboratory of Structural Sciences, Van Andel Research Institute, 333 Bostwick Avenue, N.E., Grand Rapids, Michigan 49503, USA
2 Department of Obstetrics & Gynecology, National University Hospital, Yong Loo Lin School of Medicine, Graduate School for Integrative Sciences & Engineering, National University of Singapore, Singapore 119074, Republic of Singapore
3 Department of Botany and Plant Sciences, University of California at Riverside, Riverside, California 92521, USA
4 Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
5 Center for Plant Stress Genomics and Technology, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
6 State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, National Center for Plant Gene Research, Beijing 100101, China
7 These authors contributed equally to this work.
Correspondence to: H. Eric Xu1 Correspondence and requests for materials should be addressed to H.E.X.
Abscisic acid (ABA) is a ubiquitous hormone that regulates plant growth, development and responses to environmental stresses. Its action is mediated by the PYR/PYL/RCAR family of START proteins, but it remains unclear how these receptors bind ABA and, in turn, how hormone binding leads to inhibition of the downstream type 2C protein phosphatase (PP2C) effectors. Here we report crystal structures of apo and ABA-bound receptors as well as a ternary PYL2–ABA–PP2C complex. The apo receptors contain an open ligand-binding pocket flanked by a gate that closes in response to ABA by way of conformational changes in two highly conserved -loops that serve as a gate and latch. Moreover, ABA-induced closure of the gate creates a surface that enables the receptor to dock into and competitively inhibit the PP2C active site. A conserved tryptophan in the PP2C inserts directly between the gate and latch, which functions to further lock the receptor in a closed conformation. Together, our results identify a conserved gate–latch–lock mechanism underlying ABA signalling.
