title: LNK1 and LNK2 are transcriptional coactivators in the Arabidopsis circadian oscillator.
abstract: Transcriptional feedback loops are central to the architecture of eukaryotic circadian clocks. Models of the Arabidopsis thaliana circadian clock have emphasized transcriptional repressors, but recently, Myb-like REVEILLE (RVE) transcription factors have been established as transcriptional activators of central clock components, including PSEUDO-RESPONSE REGULATOR5 (PRR5) and TIMING OF CAB EXPRESSION1 (TOC1). We show here that NIGHT LIGHT-INDUCIBLE AND CLOCK-REGULATED1 (LNK1) and LNK2, members of a small family of four LNK proteins, dynamically interact with morning-expressed oscillator components, including RVE4 and RVE8. Mutational disruption of LNK1 and LNK2 function prevents transcriptional activation of PRR5 by RVE8. The LNKs lack known DNA binding domains, yet LNK1 acts as a transcriptional activator in yeast and in planta. Chromatin immunoprecipitation shows that LNK1 is recruited to the PRR5 and TOC1 promoters in planta. We conclude that LNK1 is a transcriptional coactivator necessary for expression of the clock genes PRR5 and TOC1 through recruitment to their promoters via interaction with bona fide DNA binding proteins such as RVE4 and RVE8.
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Qiguang
authors.initials: Q
authors.lastname: Xie
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Xian
authors.initials: X
authors.lastname: Liu
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Lingbao
authors.initials: L
authors.lastname: Wang
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Chenguang
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Hongya
authors.initials: H
authors.lastname: Xing
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Liya
authors.initials: L
authors.lastname: Zhi
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Yue
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China.
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Zhao
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755-3563.
authors.forename: C Robertson
authors.initials: CR
authors.lastname: McClung
authors.affiliation: Hebei Key Laboratory of Molecular and Cellular Biology, Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Sciences, Hebei Normal University, Hebei Collaboration Innovation Center for Cell Signaling, Shijiazhuang, Hebei 050024, China xiaodong.xu@hebtu.edu.cn.
authors.forename: Xiaodong
authors.identifier: http://orcid.org/0000-0002-8795-7651
authors.initials: X
authors.lastname: Xu
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D057906:Circadian Clocks; D002940:Circadian Rhythm; D035264:Flowers / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D017930:Genes, Reporter; D008027:Light; D008957:Models, Genetic; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C000599348:LNK1 protein, Arabidopsis; C000599349:LNK2 protein, Arabidopsis; C523307:PRR5 protein, Arabidopsis; C411822:TOC1 protein, Arabidopsis; D015534:Trans-Activators; D014157:Transcription Factors