The C termini of Arabidopsis cryptochromes mediate a constitutive light response

Cell. 2000 Nov 22;103(5):815-27. doi: 10.1016/s0092-8674(00)00184-7.

Abstract

Cryptochrome blue light photoreceptors share sequence similarity to photolyases, flavoproteins that mediate light-dependent DNA repair. However, cryptochromes lack photolyase activity and are characterized by distinguishing C-terminal domains. Here we show that the signaling mechanism of Arabidopsis cryptochrome is mediated through the C terminus. On fusion with beta-glucuronidase (GUS), both the Arabidopsis CRY1 C-terminal domain (CCT1) and the CRY2 C-terminal domain (CCT2) mediate a constitutive light response. This constitutive photomorphogenic (COP) phenotype was not observed for mutants of cct1 corresponding to previously described cry1 alleles. We propose that the C-terminal domain of Arabidopsis cryptochrome is maintained in an inactive state in the dark. Irradiation with blue light relieves this repression, presumably through an intra- or intermolecular redox reaction mediated through the flavin bound to the N-terminal photolyase-like domain.

Publication types

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

MeSH terms

  • Alleles
  • Animals
  • Anthocyanins / biosynthesis
  • Arabidopsis / metabolism
  • Arabidopsis / physiology*
  • Arabidopsis Proteins
  • Cell Nucleus / metabolism
  • Cryptochromes
  • DNA Repair
  • Deoxyribodipyrimidine Photo-Lyase / chemistry
  • Drosophila
  • Drosophila Proteins*
  • Eye Proteins*
  • Flavoproteins / chemistry*
  • Flavoproteins / genetics
  • Flavoproteins / physiology*
  • Glucuronidase / metabolism
  • Humans
  • Immunoblotting
  • Light*
  • Models, Biological
  • Mutagenesis
  • Oxidation-Reduction
  • Phenotype
  • Photoreceptor Cells / physiology*
  • Photoreceptor Cells, Invertebrate*
  • Plants, Genetically Modified
  • Plastids / physiology
  • Point Mutation
  • Protein Structure, Tertiary
  • Receptors, G-Protein-Coupled
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction
  • Transgenes

Substances

  • Anthocyanins
  • Arabidopsis Proteins
  • CRY1 protein, Arabidopsis
  • CRY1 protein, human
  • CRY2 protein, human
  • Cryptochromes
  • Drosophila Proteins
  • Eye Proteins
  • Flavoproteins
  • Receptors, G-Protein-Coupled
  • Recombinant Fusion Proteins
  • cry protein, Drosophila
  • Glucuronidase
  • Deoxyribodipyrimidine Photo-Lyase