TY - JOUR
T1 - Inhibition of the Arabidopsis bHLH transcription factor by monomerization through abscisic acid-induced phosphorylation
AU - Takahashi, Yohei
AU - Kinoshita, Toshinori
AU - Matsumoto, Masaki
AU - Shimazaki, Ken Ichiro
N1 - Funding Information:
We thank Dr. E. Gotoh (Kyushu University, Japan) for technical advice on procedure of BN-PAGE. This work was supported by JSPS KAKENHI Grant numbers 21227001 (to K.S.) and 22119005 (to T.K.). We thank M. Oda and E. Koba for technical assistance with mass spectrometry. The authors have no conflict of interest to declare.
Publisher Copyright:
© 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.
PY - 2016/9/1
Y1 - 2016/9/1
N2 - We have demonstrated that the Arabidopsis basic helix-loop-helix (bHLH) transcription factor, ABA-responsive kinase substrate 1 (AKS1; also known as FLOWERING BHLH 3, FBH3), enhances K(+) channel expression in guard cells leading to stomatal opening. The expression is suppressed by ABA-induced phosphorylation of AKS1. Here we show that the phosphorylation results in the monomerization of AKS1 multimers and inhibits AKS1 binding to DNA. AKS1 forms homo-multimers which dissociate following phosphorylation. Replacement of a critical amino acid in the bHLH domain inhibited multimer formation and decreased the binding of AKS1 to DNA. The monomerization was elicited via phosphorylation at three serine residues, which is mediated by SNF1-related protein kinase 2.6 (SnRK2.6), in the vicinity of bHLH domain. Furthermore, ABA induced the phosphorylation-dependent release of AKS1 from DNA, thereby suppressing transcriptional activity in vivo. Our results document a mechanism that inhibits gene expression by phosphorylation of a bHLH transcription factor.
AB - We have demonstrated that the Arabidopsis basic helix-loop-helix (bHLH) transcription factor, ABA-responsive kinase substrate 1 (AKS1; also known as FLOWERING BHLH 3, FBH3), enhances K(+) channel expression in guard cells leading to stomatal opening. The expression is suppressed by ABA-induced phosphorylation of AKS1. Here we show that the phosphorylation results in the monomerization of AKS1 multimers and inhibits AKS1 binding to DNA. AKS1 forms homo-multimers which dissociate following phosphorylation. Replacement of a critical amino acid in the bHLH domain inhibited multimer formation and decreased the binding of AKS1 to DNA. The monomerization was elicited via phosphorylation at three serine residues, which is mediated by SNF1-related protein kinase 2.6 (SnRK2.6), in the vicinity of bHLH domain. Furthermore, ABA induced the phosphorylation-dependent release of AKS1 from DNA, thereby suppressing transcriptional activity in vivo. Our results document a mechanism that inhibits gene expression by phosphorylation of a bHLH transcription factor.
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U2 - 10.1111/tpj.13217
DO - 10.1111/tpj.13217
M3 - Article
C2 - 27227462
AN - SCOPUS:85027935869
SN - 0960-7412
VL - 87
SP - 559
EP - 567
JO - The Plant journal : for cell and molecular biology
JF - The Plant journal : for cell and molecular biology
IS - 6
ER -