title: Functional dissection of circadian clock- and phytochrome-regulated transcription of the Arabidopsis CAB2 gene.
abstract: Both the circadian clock and phytochrome regulate expression of the Arabidopsis genes encoding the light-harvesting chlorophyll a/b-binding proteins (CAB genes). Phytochrome activates CAB transcription, and it has been proposed that the circadian clock negatively regulates CAB transcription. The tobacco nuclear proteins CUF-1 (CAB upstream factor 1) and CGF-1 (CAB GATA factor 1) bind the Arabidopsis CAB2 promoter, and the CGF-1 binding site is contained within a minimal clock- and phytochrome-regulated region of the promoter. We have used in vivo cab2::luciferase gene bioluminescence markers containing site-directed mutations in the CUF-1 and CGF-1 binding sites to define the role of these proteins in CAB2 regulation and to further delineate the terminal genomic targets of the phytochrome and circadian clock signal transduction pathways. Results from these studies confirm that CUF-1 is not required to generate the circadian clock- or phytochrome-responsive CAB2 expression pattern but rather functions as a positive factor to increase CAB2 expression levels. CGF-1 interaction with the CAB2 promoter mediates the acute increase in CAB2 expression in response to phytochrome activation and contributes to the light-induced high-amplitude circadian oscillation in CAB2 expression.
authors.affiliation: National Science Foundation Center for Biological Timing, Department of Biology, University of Virginia, Charlottesville 22903.
authors.forename: S L
authors.initials: SL
authors.lastname: Anderson
authors.forename: S A
authors.initials: SA
authors.lastname: Kay
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics*; D002940:Circadian Rhythm; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010834:Phytochrome / Q000494:pharmacology*; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; C490217:CAB1 protein, Arabidopsis; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D045342:Light-Harvesting Protein Complexes; D009687:Nuclear Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D014157:Transcription Factors; D010834:Phytochrome