title: DELLA proteins and their interacting RING Finger proteins repress gibberellin responses by binding to the promoters of a subset of gibberellin-responsive genes in Arabidopsis.
abstract: DELLA proteins, consisting of GA INSENSITIVE, REPRESSOR OF GA1-3, RGA-LIKE1 (RGL1), RGL2, and RGL3, are central repressors of gibberellin (GA) responses, but their molecular functions are not fully understood. We isolated four DELLA-interacting RING domain proteins, previously designated as BOTRYTIS SUSCEPTIBLE1 INTERACTOR (BOI), BOI-RELATED GENE1 (BRG1), BRG2, and BRG3 (collectively referred to as BOIs). Single mutants of each BOI gene failed to significantly alter GA responses, but the boi quadruple mutant (boiQ) showed a higher seed germination frequency in the presence of paclobutrazol, precocious juvenile-to-adult phase transition, and early flowering, all of which are consistent with enhanced GA signaling. By contrast, BOI overexpression lines displayed phenotypes consistent with reduced GA signaling. Analysis of a gai-1 boiQ pentuple mutant further indicated that the GAI protein requires BOIs to inhibit a subset of GA responses. At the molecular level, BOIs did not significantly alter the stability of a DELLA protein. Instead, BOI and DELLA proteins are targeted to the promoters of a subset of GA-responsive genes and repress their expression. Taken together, our results indicate that the DELLA and BOI proteins inhibit GA responses by interacting with each other, binding to the same promoters of GA-responsive genes, and repressing these genes.
authors.affiliation: Department of Biological Sciences, KAIST, Daejeon 305-701, Korea.
authors.forename: Jeongmoo
authors.initials: J
authors.lastname: Park
authors.forename: Khoa Thi
authors.initials: KT
authors.lastname: Nguyen
authors.forename: Eunae
authors.initials: E
authors.lastname: Park
authors.forename: Jong-Seong
authors.initials: JS
authors.lastname: Jeon
authors.forename: Giltsu
authors.initials: G
authors.lastname: Choi
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018525:Germination; D005875:Gibberellins / Q000378:metabolism*; D010641:Phenotype; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D025941:Protein Interaction Mapping; D055550:Protein Stability; D054829:RING Finger Domains; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014230:Triazoles / Q000494:pharmacology; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; C109555:GAI protein, Arabidopsis; D005875:Gibberellins; C508468:RGA protein, Arabidopsis; C450823:RGL2 protein, Arabidopsis; D012097:Repressor Proteins; D014157:Transcription Factors; D014230:Triazoles; C053370:paclobutrazol