Direct targeting of light signals to a promoter element-bound transcription factor.
Light signals perceived by the phytochrome family of sensory photoreceptors are transduced to photoresponsive genes by an unknown mechanism. Here, we show that the basic helix-loop-helix transcription factor PIF3 binds specifically to a G-box DNA-sequence motif present in various light-regulated gene promoters, and that phytochrome B binds reversibly to G-box-bound PIF3 specifically upon light-triggered conversion of the photoreceptor to its biologically active conformer. We suggest that the phytochromes may function as integral light-switchable components of transcriptional regulator complexes, permitting continuous and immediate sensing of changes in this environmental signal directly at target gene promoters.
Martínez-García
J F
JF
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Huq
E
E
Quail
P H
PH
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D018797:Cell Cycle Proteins / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018257:Helix-Loop-Helix Motifs; D008027:Light; D008957:Models, Genetic; D009838:Oligodeoxyribonucleotides / Q000235:genetics / Q000378:metabolism; D010786:Photoreceptor Cells; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D010834:Phytochrome / Q000378:metabolism*; D051939:Phytochrome B; D010940:Plant Proteins; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D018797:Cell Cycle Proteins; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D045322:Photosynthetic Reaction Center Complex Proteins; D010834:Phytochrome; D051939:Phytochrome B; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C114425:CCA1 protein, Arabidopsis; C113192:LHY protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; C116162:PIF3 protein, Arabidopsis; C118571:SPA1 protein, Arabidopsis