title: Auxin-dependent compositional change in Mediator in ARF7- and ARF19-mediated transcription.
abstract: Mediator is a multiprotein complex that integrates the signals from transcription factors binding to the promoter and transmits them to achieve gene transcription. The subunits of Mediator complex reside in four modules: the head, middle, tail, and dissociable CDK8 kinase module (CKM). The head, middle, and tail modules form the core Mediator complex, and the association of CKM can modify the function of Mediator in transcription. Here, we show genetic and biochemical evidence that CKM-associated Mediator transmits auxin-dependent transcriptional repression in lateral root (LR) formation. The AUXIN/INDOLE 3-ACETIC ACID 14 (Aux/IAA14) transcriptional repressor inhibits the transcriptional activity of its binding partners AUXIN RESPONSE FACTOR 7 (ARF7) and ARF19 by making a complex with the CKM-associated Mediator. In addition, TOPLESS (TPL), a transcriptional corepressor, forms a bridge between IAA14 and the CKM component MED13 through the physical interaction. ChIP assays show that auxin induces the dissociation of MED13 but not the tail module component MED25 from the ARF7 binding region upstream of its target gene. These findings indicate that auxin-induced degradation of IAA14 changes the module composition of Mediator interacting with ARF7 and ARF19 in the upstream region of their target genes involved in LR formation. We suggest that this regulation leads to a quick switch of signal transmission from ARFs to target gene expression in response to auxin.
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara 630-0192, Japan;
authors.forename: Jun
authors.initials: J
authors.lastname: Ito
authors.affiliation: Department of Biology, Graduate School of Science, Kobe University, Kobe 657-8501, Japan;
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Fukaki
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara 630-0192, Japan;
authors.forename: Makoto
authors.initials: M
authors.lastname: Onoda
authors.affiliation: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Chuanyou
authors.initials: C
authors.lastname: Li
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara 630-0192, Japan;
authors.forename: Masao
authors.initials: M
authors.lastname: Tasaka
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara 630-0192, Japan; ma-furut@agr.nagoya-u.ac.jp.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Furutani
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology*; D030821:Plants, Genetically Modified; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C503426:ARF19 protein, Arabidopsis; C503425:ARF7 protein, Arabidopsis; D029681:Arabidopsis Proteins; C546591:GRAND CENTRAL protein, Arabidopsis; C507566:IAA14 protein, Arabidopsis; D007210:Indoleacetic Acids; D012097:Repressor Proteins; D014157:Transcription Factors
keywords: CDK8 kinase module; Mediator complex; auxin response; lateral root formation