title: Isolation of CONSTANS as a TGA4/OBF4 interacting protein.
abstract: Members of the TGA family of basic domain/leucine zipper transcription factors regulate defense genes through physical interaction with NON-EXPRESSOR OF PR1 (NPR1). Of the seven TGA family members, TGA4/octopine synthase (ocs)-element-binding factor 4 (OBF4) is the least understood. Here we present evidence for a novel function of OBF4 as a regulator of flowering. We identified CONSTANS (CO), a positive regulator of floral induction, as an OBF4-interacting protein, in a yeast two-hybrid library screen. OBF4 interacts with the B-box region of CO. The abundance of OBF4 mRNA cycles with a 24 h rhythm under both long-day (LD) and short-day (SD) conditions, with significantly higher levels during the night than during the day. Electrophoretic mobility shift assays revealed that OBF4 binds to the promoter of the FLOWERING LOCUS T (FT) gene, a direct target of CO. We also found that, like CO and FT, an OBF4:GUS construct was prominently expressed in the vascular tissues of leaf, indicating that OBF4 can regulate FT expression through the formation of a protein complex with CO. Taken together, our results suggest that OBF4 may act as a link between defense responses and flowering.
authors.affiliation: Environmental Biotechnology National Core Research Center, Division of Applied Life Science (Brain Korea 21 Program), Plant Molecular Biology Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea.
authors.forename: Young Hun
authors.initials: YH
authors.lastname: Song
authors.forename: Na Young
authors.initials: NY
authors.lastname: Song
authors.forename: Su Young
authors.initials: SY
authors.lastname: Shin
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Dae-Jin
authors.initials: DJ
authors.lastname: Yun
authors.forename: Chae Oh
authors.initials: CO
authors.lastname: Lim
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee
authors.forename: Kyu Young
authors.initials: KY
authors.lastname: Kang
authors.forename: Jong Chan
authors.initials: JC
authors.lastname: Hong
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D002940:Circadian Rhythm; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D035264:Flowers / Q000235:genetics* / Q000254:growth & development; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D009928:Organ Specificity; D018514:Plant Structures / Q000235:genetics* / Q000254:growth & development; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C092776:CONSTANS protein, Arabidopsis; D004268:DNA-Binding Proteins; C418905:FT protein, Arabidopsis; C084752:OBF4 protein, Arabidopsis; D014157:Transcription Factors