title: Purification of a plant mediator from Arabidopsis thaliana identifies PFT1 as the Med25 subunit.
abstract: Mediator, a central coregulator of transcription, has been identified as a large protein complex in eukaryotes ranging from yeast to man. It is therefore remarkable that Mediator has not yet been identified within the plant kingdom. Here we identify Mediator in a plant, Arabidopsis thaliana. The plant Mediator subunits typically show very low homology to other species, but our biochemical purification identifies 21 conserved and six A. thaliana-specific Mediator subunits. Most notably, we identify the A. thaliana proteins STRUWWELPETER (SWP) and PHYTOCHROME AND FLOWERING TIME 1 (PFT1) as the Med14 and Med25 subunits, respectively. These findings show that specific plant Mediator subunits are linked to the regulation of specialized processes such as the control of cell proliferation and the regulation of flowering time in response to light quality. The identification of the plant Mediator will provide new tools and insights into the regulation of transcription in plants.
authors.affiliation: Department of Medical Biochemistry and Biophysics, KBC, Umeå University, SE-901 87 Umeå, Sweden. stefan.backstrom@medchem.umu.se
authors.forename: Stefan
authors.initials: S
authors.lastname: Bäckström
authors.forename: Nils
authors.initials: N
authors.lastname: Elfving
authors.forename: Robert
authors.initials: R
authors.lastname: Nilsson
authors.forename: Gunnar
authors.initials: G
authors.lastname: Wingsle
authors.forename: Stefan
authors.initials: S
authors.lastname: Björklund
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D004268:DNA-Binding Proteins; D017343:Genes, Plant; D008954:Models, Biological; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000737:chemistry / Q000302:isolation & purification; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D021122:Protein Subunits; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D053719:Tandem Mass Spectrometry; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; C475686:PFT1 protein, Arabidopsis; D021122:Protein Subunits; C469737:STRUWWELPETER protein, Arabidopsis; D015534:Trans-Activators