title: SUPPRESSOR OF FRIGIDA4, encoding a C2H2-Type zinc finger protein, represses flowering by transcriptional activation of Arabidopsis FLOWERING LOCUS C.
abstract: FLOWERING LOCUS C (FLC), a strong floral repressor, is one of the central regulators of flowering in Arabidopsis thaliana. The expression of FLC is increased by FRIGIDA (FRI) but decreased by vernalization, a long period of cold exposure that accelerates flowering. Although many aspects of FLC regulation have been reported, it is not known how FLC is transcriptionally activated by FRI at the molecular level. We isolated suppressor of FRIGIDA4 (suf4), a mutant that flowers early as a result of low FLC expression. SUF4 encodes a nuclear-localized protein with two C2H2-type zinc finger motifs and a Pro-rich domain. SUF4 protein interacts with FRI and FRIGIDA-LIKE1 (FRL1), two genes for which single mutations have the same phenotype as suf4. SUF4 also bound to the promoter of FLC in a chromatin immunoprecipitation assay, suggesting that SUF4 acts as a transcriptional activator of FLC after forming a complex with FRI and FRL1. In addition, suf4 suppresses luminidependens (ld), a late-flowering mutation that causes an increase of FLC, and SUF4 protein directly interacts with LD. Thus, we propose that LD binds to SUF4 to suppress its activity in the absence of FRI.
authors.affiliation: National Research Laboratory of Plant Developmental Genetics, Department of Biological Sciences, Seoul National University, Seoul 151-742, Korea.
authors.forename: Sanghee
authors.initials: S
authors.lastname: Kim
authors.forename: Kyuha
authors.initials: K
authors.lastname: Choi
authors.forename: Chulmin
authors.initials: C
authors.lastname: Park
authors.forename: Hyun-Ju
authors.initials: HJ
authors.lastname: Hwang
authors.forename: Ilha
authors.initials: I
authors.lastname: Lee
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000378:metabolism; D003001:Cloning, Molecular; D005091:Exons / Q000235:genetics; D035264:Flowers / Q000502:physiology*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D007438:Introns / Q000235:genetics; D026161:MADS Domain Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D016335:Zinc Fingers
chemical_list: C419046:AGL20 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002843:Chromatin; C418902:At5g10140 protein, Arabidopsis; C414613:FRI protein, Arabidopsis; C086323:LD protein, Arabidopsis; D026161:MADS Domain Proteins; D012333:RNA, Messenger; C517314:SUF4 protein, Arabidopsis; D015534:Trans-Activators