Science：确认新的ABA受体

生命是一个艰苦绝伦的过程，尤其是对于植物而言，它们必须忍耐环境带来的压力，如干旱、冰冻和炎热，但它们装备了一整套的基因，能够帮助其面对各种有害环境条件。植物使用专门的信号，人们称之为应激激素，去面对艰难的时期和适应压力环境，以增强自身的生存。其中一种专门的激素——脱落酸（ABA）就是由植物在长期的压力环境中，尤其是干旱环境中产生的。ABA如何帮助植物忍耐干旱的分子机制尚未得到充分的理解，而对ABA受体的探索一直备受争议，包括多篇科学论文的收回，以及许多重要性受到质疑的论文的发表等。

一个由美国、加拿大和西班牙科学家组成的国际科研团队近日已确认了新的ABA受体。应用一种人工合成的、科学家通过化学基因组学确认的、能够模仿ABA的生长抑制剂pyrabactin，研究者们查明PYR/PYLs是ABA的受体，其作用位于负性调节通路的顶点。PYR/PYLs通过抑制PP2Cs蛋白的活性来调控ABA信号通路。而PP2Cs蛋白在ABA信号的传递过程中扮演关键角色。

本结果发表在Science杂志上，论文的第一作者——Sean  Cutler，敏锐的意识到先前在ABA研究领域的可疑数据，所以他采取了一种与众不同的步骤，与其他竞争者分享其数据，并在结果公布前将竞争者变成合作者。在一篇新闻稿中，加州大学植物细胞生物学中心的主任、也是论文的作者Natasha  Raikhel说：“多篇论文已试图为其发现的ABA受体做出辩护，但他们的研究结果并未经受住时间的考验……我相信这一次Cutler博士和他的团队已经分离到真正的ABA受体。”（生物谷Bioon.com）

生物谷推荐原始出处：

Science 22 May 2009:DOI: 10.1126/science.1173041

Abscisic Acid Inhibits Type 2C Protein Phosphatases via the PYR/PYL Family of START Proteins

Sang-Youl Park,1,* Pauline Fung,2,* Noriyuki Nishimura,4, Davin R. Jensen,8, Hiroaki Fujii,1 Yang Zhao,2 Shelley Lumba,2 Julia Santiago,5 Americo Rodrigues,5 Tsz-fung F. Chow,2 Simon E. Alfred,2 Dario Bonetta,6 Ruth Finkelstein,7 Nicholas J. Provart,2,3 Darrell Desveaux,2,3 Pedro L. Rodriguez,5 Peter McCourt,2 Jian-Kang Zhu,1 Julian I. Schroeder,4 Brian F. Volkman,8 Sean R. Cutler1,9,10,11,

Type 2C protein phosphatases (PP2Cs) are vitally involved in abscisic acid (ABA) signaling. Here, we show that a synthetic growth inhibitor called pyrabactin functions as a selective ABA agonist. Pyrabactin acts through PYRABACTIN RESISTANCE 1 (PYR1), the founding member of a family of START proteins called PYR/PYLs, which are necessary for both pyrabactin and ABA signaling in vivo. We show that ABA binds to PYR1, which in turn binds to and inhibits PP2Cs. We conclude that PYR/PYLs are ABA receptors functioning at the apex of a negative regulatory pathway that controls ABA signaling by inhibiting PP2Cs. Our results illustrate the power of the chemical genetic approach for sidestepping genetic redundancy.

1 Department of Botany and Plant Sciences, University of California at Riverside, Riverside, CA 92521, USA.
2 Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.
3 Centre for the Analysis of Genome Evolution and Function, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.
4 Division of Biological Sciences, Cell and Developmental Biology Section, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
5 Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia, Avenida de los Naranjos, Edificio CPI, 8E, ES-46022 Valencia, Spain.
6 Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, ON, L1H 7K4, Canada.
7 Department of Molecular, Cellular, and Developmental Biology, University of California at Santa Barbara, Santa Barbara, CA 93106, USA.
8 Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
9 Center for Plant Cell Biology, University of California at Riverside, Riverside, CA 92521, USA.
10 Institute for Genome Biology, University of California at Riverside, Riverside, CA 92521, USA.
11 Department of Chemistry, University of California at Riverside, Riverside, CA 92521, USA.