title: The Arabidopsis mediator complex subunits MED16, MED14, and MED2 regulate mediator and RNA polymerase II recruitment to CBF-responsive cold-regulated genes.
abstract: The Mediator16 (MED16; formerly termed SENSITIVE TO FREEZING6 [SFR6]) subunit of the plant Mediator transcriptional coactivator complex regulates cold-responsive gene expression in Arabidopsis thaliana, acting downstream of the C-repeat binding factor (CBF) transcription factors to recruit the core Mediator complex to cold-regulated genes. Here, we use loss-of-function mutants to show that RNA polymerase II recruitment to CBF-responsive cold-regulated genes requires MED16, MED2, and MED14 subunits. Transcription of genes known to be regulated via CBFs binding to the C-repeat motif/drought-responsive element promoter motif requires all three Mediator subunits, as does cold acclimation-induced freezing tolerance. In addition, these three subunits are required for low temperature-induced expression of some other, but not all, cold-responsive genes, including genes that are not known targets of CBFs. Genes inducible by darkness also required MED16 but required a different combination of Mediator subunits for their expression than the genes induced by cold. Together, our data illustrate that plants control transcription of specific genes through the action of subsets of Mediator subunits; the specific combination defined by the nature of the stimulus but also by the identity of the gene induced.
authors.affiliation: Durham Centre for Crop Improvement Technology, School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, United Kingdom.
authors.forename: Piers A
authors.initials: PA
authors.lastname: Hemsley
authors.forename: Charlotte H
authors.initials: CH
authors.lastname: Hurst
authors.forename: Ewon
authors.initials: E
authors.lastname: Kaliyadasa
authors.forename: Rebecca
authors.initials: R
authors.lastname: Lamb
authors.forename: Marc R
authors.initials: MR
authors.lastname: Knight
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: De Cothi
authors.forename: John F
authors.initials: JF
authors.lastname: Steele
authors.forename: Heather
authors.initials: H
authors.lastname: Knight
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D042002:Chromatin Assembly and Disassembly; D057773:Cold Shock Proteins and Peptides / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D056892:Mediator Complex / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012319:RNA Polymerase II / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D057773:Cold Shock Proteins and Peptides; D056892:Mediator Complex; D012319:RNA Polymerase II; D015534:Trans-Activators; C000592973:MED32 protein, Arabidopsis; C575423:SFR6 protein, Arabidopsis; C469737:STRUWWELPETER protein, Arabidopsis