title: DELLAs function as coactivators of GAI-ASSOCIATED FACTOR1 in regulation of gibberellin homeostasis and signaling in Arabidopsis.
abstract: Gibberellins (GAs) are essential regulators of plant development, and DELLAs are negative regulators of GA signaling. The mechanism of GA-dependent transcription has been explained by DELLA-mediated titration of transcriptional activators and their release through the degradation of DELLAs in response to GA. However, the effect of GA on genome-wide expression is predominantly repression, suggesting the existence of unknown mechanisms of GA function. In this study, we identified an Arabidopsis thaliana DELLA binding transcription factor, GAI-ASSOCIATED FACTOR1 (GAF1). GAF1 shows high homology to INDETERMINATE DOMAIN1 (IDD1)/ENHYDROUS. GA responsiveness was decreased in the double mutant gaf1 idd1, whereas it was enhanced in a GAF1 overexpressor. GAF1 binds to genes that are subject to GA feedback regulation. Furthermore, we found that GAF1 interacts with the corepressor TOPLESS RELATED (TPR) and that DELLAs and TPR act as coactivators and a corepressor of GAF1, respectively. GA converts the GAF1 complex from transcriptional activator to repressor via the degradation of DELLAs. These results indicate that DELLAs turn on or off two sets of GA-regulated genes via dual functions, namely titration and coactivation, providing a mechanism for the integrative regulation of plant growth and GA homeostasis.
authors.affiliation: Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan RIKEN Plant Science Center, Tsurumi, Yokohama, Kanagawa 230-0045, Japan Department of Biological Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan jutarouf@hiroshima-u.ac.jp.
authors.forename: Jutarou
authors.initials: J
authors.lastname: Fukazawa
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Teramura
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Murakoshi
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Nasuno
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan.
authors.forename: Naotaka
authors.initials: N
authors.lastname: Nishida
authors.affiliation: Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ito
authors.affiliation: Department of Biological Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan.
authors.forename: Michiteru
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: RIKEN Plant Science Center, Tsurumi, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.affiliation: RIKEN Plant Science Center, Tsurumi, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Yohsuke
authors.initials: Y
authors.lastname: Takahashi
mesh_terms: D000906:Antibodies; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D005875:Gibberellins / Q000378:metabolism*; D006706:Homeostasis; D016254:Mutagenesis, Insertional; D010937:Plant Growth Regulators / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D043262:Ribonuclease P / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000166:cytology / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques
chemical_list: D000906:Antibodies; D029681:Arabidopsis Proteins; C109555:GAI protein, Arabidopsis; D005875:Gibberellins; D010937:Plant Growth Regulators; C551919:topless-related 1 protein, Arabidopsis; C574372:GAF1 protein, Arabidopsis; D043262:Ribonuclease P