title: Binding of GID1 to DELLAs promotes dissociation of GAF1 from DELLA in GA dependent manner.
abstract: Gibberellins (GAs) are important phytohormones for plant growth and development. DELLAs are members of the plant-specific GRAS protein family and act as repressors of GA signaling. DELLAs are rapidly degraded in the presence of GAs. GA-GID1-DELLA complexes are recognized and ubiquitinated by the SCF(SLY) complex. The sleepy1 (sly1) F-box mutant exhibits dwarfism and low-germination phenotypes due to high accumulation of DELLAs. Overexpression of GID1 in the sly1 mutant partially rescues these phenotypes without degradation of DELLAs suggesting that proteolysis independent regulation of DELLAs exists in GA signaling. But the molecular mechanisms of non-proteolytic regulation of DELLA are largely unknown. Recently we identified a DELLA binding transcription factor, GAI-ASSOCIATED FACTOR1 (GAF1). GAF1 also interacts with co-repressor TOPLESS RELATED (TPR) in nuclei. DELLAs and TPR act as coactivator and corepressor of GAF1, respectively. GAs converts the GAF1 complex from transcriptional activator to repressor via degradation of DELLAs. The overexpression of ΔPAM, lacking of DELLAs binding region of GAF1, partially rescue dwarf phenotypes of GA deficient or GA insensitive mutant. In this study, we investigate the relationship between non-proteolytic regulation of DELLAs and GA signaling via DELLA-GAF1 complex using modified yeast two-hybrid system.
authors.affiliation: a Department of Biological Science ; Graduate School of Science, Hiroshima University ; Kagamiyama , Higashi-Hiroshima , Japan.|b RIKEN Plant Science Center ; Yokohama , Kanagawa , Japan.
authors.forename: Jutarou
authors.initials: J
authors.lastname: Fukazawa
authors.affiliation: a Department of Biological Science ; Graduate School of Science, Hiroshima University ; Kagamiyama , Higashi-Hiroshima , Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ito
authors.affiliation: b RIKEN Plant Science Center ; Yokohama , Kanagawa , Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.affiliation: b RIKEN Plant Science Center ; Yokohama , Kanagawa , Japan.
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: a Department of Biological Science ; Graduate School of Science, Hiroshima University ; Kagamiyama , Higashi-Hiroshima , Japan.
authors.forename: Yohsuke
authors.initials: Y
authors.lastname: Takahashi
mesh_terms: D029681:Arabidopsis Proteins / Q000378:metabolism; D056970:Co-Repressor Proteins / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism*; D010641:Phenotype; D063245:Plant Development / Q000235:genetics*; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D010944:Plants / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism; D043262:Ribonuclease P / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D056970:Co-Repressor Proteins; C109555:GAI protein, Arabidopsis; C512225:GID1a protein, Arabidopsis; D005875:Gibberellins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011956:Receptors, Cell Surface; D014157:Transcription Factors; C574372:GAF1 protein, Arabidopsis; D043262:Ribonuclease P
keywords: DELLA; GAF1; GID1; SLY1; TOPLESS; gibberellin; proteolysis; signaling; transcription factor