The flowering time regulator CONSTANS is recruited to the FLOWERING LOCUS T promoter via a unique cis-element

New Phytol. 2010 Jul;187(1):57-66. doi: 10.1111/j.1469-8137.2010.03251.x. Epub 2010 Apr 12.


CONSTANS is an evolutionarily-conserved central component of the genetic pathway that controls the onset of flowering in response to daylength. However, the specific biochemical mechanism by which the CONSTANS protein regulates the expression of its target genes remains largely unknown. *By using a combination of cell-based expression analysis and in vitro DNA binding studies, we have demonstrated that CONSTANS possesses transcriptional activation potential and is capable of directly binding to DNA. *CONSTANS was found to bind DNA via a unique sequence element containing a consensus TGTG(N2-3)ATG motif. This element is present in tandem within the FLOWERING LOCUS T promoter and is sufficient for CO binding and activity. The conserved CCT (CONSTANS, CONSTANS-like and TOC1) domain of CONSTANS was shown to be required for its recruitment to the DNA motif and other CCT-containing proteins were also found to have the ability to regulate gene expression via this element. *The CCAAT box, which has been previously hypothesized as a recruitment site for complexes containing the CONSTANS protein, potentiated CONSTANS-mediated activation but was not essential for CONSTANS recruitment to a target promoter or for its activity as a transcriptional factor.

MeSH terms

  • Amino Acid Motifs
  • Arabidopsis / genetics*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Flowers / genetics*
  • Gene Expression Regulation, Plant
  • Genes, Plant
  • Genes, Reporter
  • Glutamine / metabolism
  • Molecular Sequence Data
  • Promoter Regions, Genetic / genetics*
  • Protein Binding
  • Protein Structure, Tertiary
  • Response Elements / genetics
  • Time Factors
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism*
  • Transcriptional Activation / genetics


  • Arabidopsis Proteins
  • CONSTANS protein, Arabidopsis
  • DNA-Binding Proteins
  • FT protein, Arabidopsis
  • Transcription Factors
  • Glutamine