title: The C termini of Arabidopsis cryptochromes mediate a constitutive light response.
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.
authors: Plant Science Institute Department of Biology University of Pennsylvania, Philadelphia, PA 19104, USA.
authors: H Q
authors: HQ
authors: Yang
authors: Y J
authors: YJ
authors: Wu
authors: R H
authors: RH
authors: Tang
authors: D
authors: D
authors: Liu
authors: Y
authors: Y
authors: Liu
authors: A R
authors: AR
authors: Cashmore
mesh_terms: D000483:Alleles; D000818:Animals; D000872:Anthocyanins / Q000096:biosynthesis; D017360:Arabidopsis / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins; D002467:Cell Nucleus / Q000378:metabolism; D056931:Cryptochromes; D004260:DNA Repair; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000737:chemistry; D004330:Drosophila; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D005966:Glucuronidase / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008027:Light; D008954:Models, Biological; D016296:Mutagenesis; D010084:Oxidation-Reduction; D010641:Phenotype; D010786:Photoreceptor Cells / Q000502:physiology*; D017956:Photoreceptor Cells, Invertebrate; D030821:Plants, Genetically Modified; D018087:Plastids / Q000502:physiology; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D019076:Transgenes
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; C538963:CRY1 protein, human; C538966:CRY2 protein, human; D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins; C119828:cry protein, Drosophila; D005966:Glucuronidase; D004255:Deoxyribodipyrimidine Photo-Lyase