title: The phytochrome-interacting factor PIF7 negatively regulates DREB1 expression under circadian control in Arabidopsis.
abstract: Transcription factors of the DRE-Binding1 (DREB1)/C-repeat binding factor family specifically interact with a cis-acting dehydration-responsive element/C-repeat involved in low-temperature stress-responsive gene expression in Arabidopsis (Arabidopsis thaliana). Expression of DREB1s is induced by low temperatures and is regulated by the circadian clock under unstressed conditions. Promoter sequences of DREB1s contain six conserved motifs, boxes I to VI. We analyzed the promoter region of DREB1C using transgenic plants and found that box V with the G-box sequence negatively regulates DREB1C expression under circadian control. The region around box VI contains positive regulatory elements for low-temperature-induced expression of DREB1C. Using yeast one-hybrid screens, we isolated cDNA encoding the transcriptional factor Phytochrome-Interacting Factor7 (PIF7), which specifically binds to the G-box of the DREB1C promoter. The PIF7 gene was expressed in rosette leaves, and the PIF7 protein was localized in the nuclei of the cells. Transactivation experiments using Arabidopsis protoplasts indicated that PIF7 functions as a transcriptional repressor for DREB1C expression and that its activity is regulated by PIF7-interacting factors TIMING OF CAB EXPRESSION1 and Phytochrome B, which are components of the circadian oscillator and the red light photoreceptor, respectively. Moreover, in the pif7 mutant, expression of DREB1B and DREB1C was not repressed under light conditions, indicating that PIF7 functions as a transcriptional repressor for the expression of DREB1B and DREB1C under circadian control. This negative regulation of DREB1 expression may be important for avoiding plant growth retardation by the accumulation of DREB1 proteins under unstressed conditions.
authors.affiliation: Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kidokoro
authors.forename: Kyonoshin
authors.initials: K
authors.lastname: Maruyama
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nakashima
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Imura
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Narusaka
authors.forename: Zabta K
authors.initials: ZK
authors.lastname: Shinwari
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Osakabe
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Fujita
authors.forename: Junya
authors.initials: J
authors.lastname: Mizoi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shinozaki
authors.forename: Kazuko
authors.initials: K
authors.lastname: Yamaguchi-Shinozaki
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D020029:Base Pairing / Q000235:genetics; D001483:Base Sequence; D002940:Circadian Rhythm / Q000235:genetics*; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010834:Phytochrome / Q000378:metabolism*; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D021381:Protein Transport; D011523:Protoplasts / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C114578:DREB1A protein, Arabidopsis; C547219:PIF7 protein, Arabidopsis; D014157:Transcription Factors; D010834:Phytochrome