Type 2C protein phosphatases directly regulate abscisic acid-activated protein kinases in Arabidopsis

作者：Taishi Umezawa, Naoyuki Sugiyama, Masahide Mizoguchi, Shimpei Hayashi, Fumiyoshi Myouga, Kazuko Yamaguchi‐Shinozaki, Yasushi Ishihama, Takashi Hirayama, Kazuo Shinozaki · 发表于：Proceedings of the National Academy of Sciences · 年份：2009 · DOI：10.1073/pnas.0907095106 · 被引用次数：1142 · 研究领域：Plant Stress Responses and Tolerance、Plant nutrient uptake and metabolism、Plant Molecular Biology Research

Abscisic acid (ABA) signaling is important for stress responses and developmental processes in plants. A subgroup of protein phosphatase 2C (group A PP2C) or SNF1-related protein kinase 2 (subclass III SnRK2) have been known as major negative or positive regulators of ABA signaling, respectively. Here, we demonstrate the physical and functional linkage between these two major signaling factors. Group A PP2Cs interacted physically with SnRK2s in various combinations, and efficiently inactivated ABA-activated SnRK2s via dephosphorylation of multiple Ser/Thr residues in the activation loop. This step was suppressed by the RCAR/PYR ABA receptors in response to ABA. However the abi1-1 mutated PP2C did not respond to the receptors and constitutively inactivated SnRK2. Our results demonstrate that group A PP2Cs act as 'gatekeepers' of subclass III SnRK2s, unraveling an important regulatory mechanism of ABA signaling.