title: LWD-TCP complex activates the morning gene CCA1 in Arabidopsis.
abstract: A double-negative feedback loop formed by the morning genes CIRCADIAN CLOCK ASSOCIATED1 (CCA1)/LATE ELONGATED HYPOCOTYL (LHY) and the evening gene TIMING OF CAB EXPRESSION1 (TOC1) contributes to regulation of the circadian clock in Arabidopsis. A 24-h circadian cycle starts with the peak expression of CCA1 at dawn. Although CCA1 is targeted by multiple transcriptional repressors, including PSEUDO-RESPONSE REGULATOR9 (PRR9), PRR7, PRR5 and CCA1 HIKING EXPEDITION (CHE), activators of CCA1 remain elusive. Here we use mathematical modelling to infer a co-activator role for LIGHT-REGULATED WD1 (LWD1) in CCA1 expression. We show that the TEOSINTE BRANCHED 1-CYCLOIDEA-PCF20 (TCP20) and TCP22 proteins act as LWD-interacting transcriptional activators. The concomitant binding of LWD1 and TCP20/TCP22 to the TCP-binding site in the CCA1 promoter activates CCA1. Our study reveals activators of the morning gene CCA1 and provides an action mechanism that ensures elevated expression of CCA1 at dawn to sustain a robust clock.
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Jing-Fen
authors.initials: JF
authors.lastname: Wu
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Huang-Lung
authors.identifier: 0000-0003-3467-0507
authors.initials: HL
authors.lastname: Tsai
authors.affiliation: Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan.|Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 300, Taiwan.|Bioinformatics Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan.|Institute of Bioinformatics and System Biology, National Chiao Tung University, Hsinchu 300, Taiwan.
authors.forename: Ignasius
authors.initials: I
authors.lastname: Joanito
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Yi-Chen
authors.initials: YC
authors.lastname: Wu
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Chin-Wen
authors.initials: CW
authors.lastname: Chang
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Yi-Hang
authors.initials: YH
authors.lastname: Li
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Division of Life Science, Applied Life Science (BK21 Plus Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea.|Division of Plant Sciences, University of Missouri, Columbia, South Carolina MO 65211-7310, USA.
authors.forename: Jong Chan
authors.initials: JC
authors.lastname: Hong
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 300, Taiwan.|Bioinformatics Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan.|Institute of Bioinformatics and System Biology, National Chiao Tung University, Hsinchu 300, Taiwan.
authors.forename: Jhih-Wei
authors.initials: JW
authors.lastname: Chu
authors.affiliation: Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan.|Genome and Systems Biology Degree Program, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Chao-Ping
authors.initials: CP
authors.lastname: Hsu
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.|Genome and Systems Biology Degree Program, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Shu-Hsing
authors.identifier: 0000-0002-7179-3138
authors.initials: SH
authors.lastname: Wu
mesh_terms: D000872:Anthocyanins / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D008957:Models, Genetic; D056950:Period Circadian Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; C000628192:LWD1 protein, Arabidopsis; C514751:PRR9 protein, Arabidopsis; D056950:Period Circadian Proteins; C540502:TCP20 protein, Arabidopsis; D014157:Transcription Factors