title: Arabidopsis TTG2 regulates TRY expression through enhancement of activator complex-triggered activation.
abstract: Trichome patterning in Arabidopsis thaliana is regulated by a regulatory feedback loop of the trichome promoting factors TRANSPARENT TESTA GLABRA1 (TTG1), GLABRA3 (GL3)/ENHANCER OF GL3 (EGL3), and GL1 and a group of homologous R3MYB proteins that act as their inhibitors. Together, they regulate the temporal and spatial expression of GL2 and TTG2, which are considered to control trichome cell differentiation. In this work, we show that TTG2 is a specific activator of TRY (but not CPC or GL2). The WRKY protein TTG2 binds to W-boxes in a minimal promoter fragment of TRY, and these W-boxes are essential for rescue of the try mutant phenotype. We further show that TTG2 alone is not able to activate TRY expression, but rather drastically enhances the activation by TTG1 and GL3. As TTG2 physically interacts with TTG1 and because TTG2 can associate with GL3 through its interaction with TTG1, we propose that TTG2 enhances the activity of TTG1 and GL3 by forming a protein complex.
authors.affiliation: Biocenter, Cologne University, Botanical Institute, 50674 Cologne, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Pesch
authors.affiliation: Biocenter, Cologne University, Botanical Institute, 50674 Cologne, Germany.
authors.forename: Burcu
authors.initials: B
authors.lastname: Dartan
authors.affiliation: Department of Plant Microbe Interaction, Max Planck Institute of Plant Breeding Research, Cologne 50829, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Birkenbihl
authors.affiliation: Department of Plant Microbe Interaction, Max Planck Institute of Plant Breeding Research, Cologne 50829, Germany.
authors.forename: Imre E
authors.initials: IE
authors.lastname: Somssich
authors.affiliation: Biocenter, Cologne University, Botanical Institute, 50674 Cologne, Germany martin.huelskamp@uni-koeln.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Hülskamp
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D002478:Cells, Cultured; D018506:Gene Expression Regulation, Plant; D018613:Microscopy, Confocal; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation; D064201:Trichomes / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D046912:Multiprotein Complexes; D015534:Trans-Activators; D014157:Transcription Factors; C417284:GL3 protein, Arabidopsis; C587574:TRYPTICHON protein, Arabidopsis; C121067:TTG1 protein, Arabidopsis; C525050:TTG2 protein, Arabidopsis