Targeted destabilization of HY5 during light-regulated development of Arabidopsis

Nature. 2000 May 25;405(6785):462-6. doi: 10.1038/35013076.


Arabidopsis seedlings display contrasting developmental patterns depending on the ambient light. Seedlings grown in the light develop photomorphogenically, characterized by short hypocotyls and expanded green cotyledons. In contrast, seedlings grown in darkness become etiolated, with elongated hypocotyls and dosed cotyledons on an apical hook. Light signals, perceived by multiple photoreceptors and transduced to downstream regulators, dictate the extent of photomorphogenic development in a quantitative manner. Two key downstream components, COP1 and HY5, act antagonistically in regulating seedling development. HY5 is a bZIP transcription factor that binds directly to the promoters of light-inducible genes, promoting their expression and photomorphogenic development. COP1 is a RING-finger protein with WD-40 repeats whose nuclear abundance is negatively regulated by light. COP1 interacts directly with HY5 in the nucleus to regulate its activity negatively. Here we show that the abundance of HY5 is directly correlated with the extent of photomorphogenic development, and that the COP1-HY5 interaction may specifically target HY5 for proteasome-mediated degradation in the nucleus.

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

  • Arabidopsis / growth & development*
  • Arabidopsis / radiation effects
  • Arabidopsis Proteins*
  • Basic-Leucine Zipper Transcription Factors
  • Carrier Proteins / physiology
  • Cysteine Endopeptidases / metabolism
  • Darkness
  • Light
  • Molecular Sequence Data
  • Multienzyme Complexes / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Nuclear Proteins / physiology*
  • Photosynthetic Reaction Center Complex Proteins / metabolism
  • Plant Proteins / genetics
  • Plant Proteins / physiology*
  • Plants, Genetically Modified
  • Proteasome Endopeptidase Complex
  • RNA, Messenger / metabolism
  • Ubiquitin-Protein Ligases*


  • Arabidopsis Proteins
  • Basic-Leucine Zipper Transcription Factors
  • Carrier Proteins
  • HY5 protein, Arabidopsis
  • Multienzyme Complexes
  • Nuclear Proteins
  • Photosynthetic Reaction Center Complex Proteins
  • Plant Proteins
  • RNA, Messenger
  • AT2G32950 protein, Arabidopsis
  • Ubiquitin-Protein Ligases
  • Cysteine Endopeptidases
  • Proteasome Endopeptidase Complex