Abscisic acid-dependent multisite phosphorylation regulates the activity of a transcription activator AREB1

Proc Natl Acad Sci U S A. 2006 Feb 7;103(6):1988-93. doi: 10.1073/pnas.0505667103. Epub 2006 Jan 30.


bZIP-type transcription factors AREBs/ABFs bind an abscisic acid (ABA)-responsive cis-acting element named ABRE and transactivate downstream gene expression in Arabidopsis. Because AREB1 overexpression could not induce downstream gene expression, activation of AREB1 requires ABA-dependent posttranscriptional modification. We confirmed that ABA activated 42-kDa kinase activity, which, in turn, phosphorylated Ser/Thr residues of R-X-X-S/T sites in the conserved regions of AREB1. Amino acid substitutions of R-X-X-S/T sites to Ala suppressed transactivation activity, and multiple substitution of these sites resulted in almost complete suppression of transactivation activity in transient assays. In contrast, substitution of the Ser/Thr residues to Asp resulted in high transactivation activity without exogenous ABA application. A phosphorylated, transcriptionally active form was achieved by substitution of Ser/Thr in all conserved R-X-X-S/T sites to Asp. Transgenic plants overexpressing the phosphorylated active form of AREB1 expressed many ABA-inducible genes, such as RD29B, without ABA treatment. These results indicate that the ABA-dependent multisite phosphorylation of AREB1 regulates its own activation in plants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / pharmacology*
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Arabidopsis / chemistry
  • Arabidopsis / drug effects*
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Basic-Leucine Zipper Transcription Factors / chemistry
  • Basic-Leucine Zipper Transcription Factors / genetics
  • Basic-Leucine Zipper Transcription Factors / metabolism*
  • Conserved Sequence
  • Gene Expression Regulation, Plant / drug effects*
  • Molecular Sequence Data
  • Mutation / genetics
  • Oligonucleotide Array Sequence Analysis
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Phosphorylation / drug effects
  • RNA, Messenger / genetics
  • Sequence Alignment
  • Trans-Activators / chemistry
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*


  • AREB1 protein, Arabidopsis
  • Arabidopsis Proteins
  • Basic-Leucine Zipper Transcription Factors
  • Peptide Fragments
  • RNA, Messenger
  • Trans-Activators
  • Abscisic Acid