Isolation of CONSTANS as a TGA4/OBF4 interacting protein.
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.
Song
Young Hun
YH
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.
Song
Na Young
NY
Shin
Su Young
SY
Kim
Hye Jin
HJ
Yun
Dae-Jin
DJ
Lim
Chae Oh
CO
Lee
Sang Yeol
SY
Kang
Kyu Young
KY
Hong
Jong Chan
JC
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
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