title: CESTA, a positive regulator of brassinosteroid biosynthesis.
abstract: Brassinosteroids (BRs) are steroid hormones that are essential for the development of plants. A tight control of BR homeostasis is vital for modulating their impact on growth responses. Although it is recognized that the rapid adaptation of de novo synthesis has a key role in adjusting required BR levels, our knowledge of the mechanisms governing feedback control is limited. In this study, we identify the transcription factor CESTA as a regulator of BR biosynthesis. ces-D was isolated in a screen of Arabidopsis mutants by BR over-accumulation phenotypes. Loss-of-function analysis and the use of a dominant repressor version revealed functional overlap among CESTA and its homologues and confirmed the role of CESTA in the positive control of BR-biosynthetic gene expression. We provide evidence that CESTA interacts with its homologue BEE1 and can directly bind to a G-box motif in the promoter of the BR biosynthesis gene CPD. Moreover, we show that CESTA subnuclear localization is BR regulated and discuss a model, in which CESTA interplays with BEE1 to control BR biosynthesis and other BR responses.
authors.affiliation: Centre for Novel Agricultural Products, Department of Biology, University of York, York, UK. brigitte.poppenberger@univie.ac.at
authors.forename: Brigitte
authors.initials: B
authors.lastname: Poppenberger
authors.forename: Wilfried
authors.initials: W
authors.lastname: Rozhon
authors.forename: Mamoona
authors.initials: M
authors.lastname: Khan
authors.forename: Sigrid
authors.initials: S
authors.lastname: Husar
authors.forename: Gerhard
authors.initials: G
authors.lastname: Adam
authors.forename: Christian
authors.initials: C
authors.lastname: Luschnig
authors.forename: Shozo
authors.initials: S
authors.lastname: Fujioka
authors.forename: Tobias
authors.initials: T
authors.lastname: Sieberer
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000235:genetics*; D060406:Brassinosteroids; D002777:Cholestanols / Q000378:metabolism*; D005786:Gene Expression Regulation; D010937:Plant Growth Regulators / Q000096:biosynthesis*; D025941:Protein Interaction Mapping; D013260:Steroids, Heterocyclic / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D002777:Cholestanols; D010937:Plant Growth Regulators; D013260:Steroids, Heterocyclic; D014157:Transcription Factors; C023623:brassinolide