Initiation and amplification of SnRK2 activation in abscisic acid signaling

Zhen Lin, Yuan Li, Yubei Wang, Xiaolei Liu, Liang Ma, Zhengjing Zhang, Chen Mu, Yan Zhang, Li Peng, Shaojun Xie, Chun Peng Song, Huazhong Shi, Jian Kang Zhu, Pengcheng Wang

Research output: Contribution to journalArticlepeer-review

Abstract

The phytohormone abscisic acid (ABA) is crucial for plant responses to environmental challenges. The SNF1-regulated protein kinase 2s (SnRK2s) are key components in ABA-receptor coupled core signaling, and are rapidly phosphorylated and activated by ABA. Recent studies have suggested that Raf-like protein kinases (RAFs) participate in ABA-triggered SnRK2 activation. In vitro kinase assays also suggest the existence of autophosphorylation of SnRK2s. Thus, how SnRK2 kinases are quickly activated during ABA signaling still needs to be clarified. Here, we show that both B2 and B3 RAFs directly phosphorylate SnRK2.6 in the kinase activation loop. This transphosphorylation by RAFs is essential for SnRK2 activation. The activated SnRK2s then intermolecularly trans-phosphorylate other SnRK2s that are not yet activated to amplify the response. High-order Arabidopsis mutants lacking multiple B2 and B3 RAFs show ABA hyposensitivity. Our findings reveal a unique initiation and amplification mechanism of SnRK2 activation in ABA signaling in higher plants.

Original languageEnglish
Article number2456
JournalNature Communications
Volume12
Issue number1
DOIs
StatePublished - Dec 2021

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