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

Proc Natl Acad Sci U S A. 2009 Oct 13;106(41):17588-93. doi: 10.1073/pnas.0907095106. Epub 2009 Sep 29.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / pharmacology
  • Abscisic Acid / physiology*
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Genetic Complementation Test
  • Kinetics
  • Phosphoprotein Phosphatases / antagonists & inhibitors
  • Phosphoprotein Phosphatases / genetics
  • Phosphoprotein Phosphatases / metabolism*
  • Phosphorylation
  • Plant Leaves / metabolism
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Protein Phosphatase 2C
  • Recombinant Proteins / metabolism
  • Vicia faba / genetics
  • Vicia faba / metabolism


  • Arabidopsis Proteins
  • Recombinant Proteins
  • Abscisic Acid
  • Protein Kinases
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 2C