Article abstract
Nature Structural & Molecular Biology
Published online: 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.
- State Key Laboratory of Bio-membrane and Membrane Biotechnology
- Center for Structural Biology, School of Life Sciences
- School of Medicine, Tsinghua University, Beijing, China.
- These authors contributed equally to this work.
Correspondence to: Nieng Yan1,3 e-mail: nyan@tsinghua.edu.cn
