title: A bZIP protein, VIP1, is a regulator of osmosensory signaling in Arabidopsis.
abstract: Abscisic acid is a stress-related phytohormone that has roles in dehydration and rehydration. In Arabidopsis (Arabidopsis thaliana), two genes that inactivate abscisic acid, CYP707A1 and CYP707A3, are rapidly up-regulated upon rehydration. The factors that regulate CYP707A1/3 are not well characterized. We expressed a bZIP protein, VIP1, as a green fluorescent protein fusion protein in Arabidopsis and found that the nuclear localization of VIP1 was enhanced within 10 min after rehydration. A yeast one-hybrid assay revealed that the amino-terminal region of VIP1 has transcriptional activation potential. In a transient reporter assay using Arabidopsis protoplasts, VIP1 enhanced the promoter activities of CYP707A1/3. In gel shift and chromatin immunoprecipitation analyses, VIP1 directly bound to DNA fragments of the CYP707A1/3 promoters. Transgenic plants expressing VIP1-green fluorescent protein were found to overexpress CYP707A1/3 mRNAs. The time course of nuclear-cytoplasmic shuttling of VIP1 was consistent with the time courses of the expression of CYP707A1/3. These results suggest that VIP1 functions as a regulator of osmosensory signaling in Arabidopsis.
authors.affiliation: Asian Natural Environmental Science Center, University of Tokyo, Nishitokyo-shi, Tokyo 188-0002, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tsugama
authors.forename: Shenkui
authors.initials: S
authors.lastname: Liu
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Takano
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D015151:Immunoblotting; D008353:Mannitol / Q000494:pharmacology; D009997:Osmotic Pressure; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C432104:VIP1 protein, Arabidopsis; D049452:Green Fluorescent Proteins; D008353:Mannitol; D000040:Abscisic Acid; D003577:Cytochrome P-450 Enzyme System; C523532:cytochrome P-450 703A2, Arabidopsis