HY5, Circadian Clock-Associated 1, and a cis-element, DET1 dark response element, mediate DET1 regulation of chlorophyll a/b-binding protein 2 expression

Plant Physiol. 2003 Dec;133(4):1565-77. doi: 10.1104/pp.103.025114. Epub 2003 Oct 16.


DET1 is a pleiotropic regulator of Arabidopsis development and controls the expression of many light-regulated genes. To gain a better understanding of the mechanism by which DET1 controls transcription from light-regulated promoters, we identified elements in the chlorophyll a/b-binding protein 2 (CAB2) promoter that are required for DET1-mediated expression. Using a series of reporter constructs in which the luciferase gene is controlled by CAB2 promoter fragments, we defined two DET1-responsive elements in the CAB2 promoter that are essential for proper CAB2 transcription. A 40-bp DET1 dark-response element (DtRE) is required for both dark and root-specific repression of CAB2, whereas the known CAB upstream factor-1 element is required for DET1 activation-associated effects in the light and repression in the roots. HY5, a factor that binds CAB upstream factor-1, is also required for DET1 effects in the light. DtRE binds two distinct activities in Arabidopsis seedling extracts: a novel activity with binding site CAAAACGC that we have named CAB2 DET1-associated factor 1 plus an activity that is likely to be the myb transcription factor Circadian Clock-Associated 1. Both activities are altered in dark-grown det1 extracts as compared with wild type, correlating a change in extractable DNA binding activity with a major change in CAB2 expression. We conclude that DET1 represses the CAB2 promoter in the dark by regulating the binding of two factors, CAB2 DET1-associated factor 1 and Circadian Clock-Associated 1, to the DtRE.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis / radiation effects
  • Arabidopsis Proteins / genetics*
  • Base Sequence
  • Basic-Leucine Zipper Transcription Factors
  • Binding Sites
  • Circadian Rhythm / genetics*
  • Coleoptera
  • Darkness
  • Gene Expression Regulation, Plant / radiation effects*
  • Genes, Reporter
  • Intracellular Signaling Peptides and Proteins
  • Light
  • Luciferases / genetics
  • Molecular Sequence Data
  • Nuclear Proteins / genetics*
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / growth & development
  • Plants, Genetically Modified / radiation effects
  • Sequence Alignment
  • Transcription Factors / genetics*


  • Arabidopsis Proteins
  • Basic-Leucine Zipper Transcription Factors
  • CCA1 protein, Arabidopsis
  • DET1 protein, Arabidopsis
  • HY5 protein, Arabidopsis
  • Intracellular Signaling Peptides and Proteins
  • Nuclear Proteins
  • Transcription Factors
  • Luciferases