title: Combinatorial control of Arabidopsis proline dehydrogenase transcription by specific heterodimerisation of bZIP transcription factors.
abstract: Proline metabolism has been implicated in plant responses to abiotic stresses. The Arabidopsis thaliana proline dehydrogenase (ProDH) is catalysing the first step in proline degradation. Transcriptional activation of ProDH by hypo-osmolarity is mediated by an ACTCAT cis element, a typical binding site of basic leucine zipper (bZIP) transcription factors. In this study, we demonstrate by gain-of-function and loss-of-function approaches, as well as chromatin immunoprecipitation (ChIP), that ProDH is a direct target gene of the group-S bZIP factor AtbZIP53. Dimerisation studies making use of yeast and Arabidopsis protoplast-based two-hybrid systems, as well as bimolecular fluorescence complementation (BiFC) reveal that AtbZIP53 does not preferentially form dimers with group-S bZIPs but strongly interacts with members of group-C. In particular, a synergistic interplay of AtbZIP53 and group-C AtbZIP10 was demonstrated by colocalisation studies, strong enhancement of ACTCAT-mediated transcription as well as complementation studies in atbzip53 atbzip10 T-DNA insertion lines. Heterodimer mediated activation of transcription has been found to operate independent of the DNA-binding properties and is described as a crucial mechanism to modulate transcription factor activity and function.
authors.affiliation: Albrecht-von-Haller Institut, Universität Göttingen, Göttingen, Germany.
authors.forename: Fridtjof
authors.initials: F
authors.lastname: Weltmeier
authors.forename: Andrea
authors.initials: A
authors.lastname: Ehlert
authors.forename: Caroline S
authors.initials: CS
authors.lastname: Mayer
authors.forename: Katrin
authors.initials: K
authors.lastname: Dietrich
authors.forename: Xuan
authors.initials: X
authors.lastname: Wang
authors.forename: Katia
authors.initials: K
authors.lastname: Schütze
authors.forename: Rosario
authors.initials: R
authors.lastname: Alonso
authors.forename: Klaus
authors.initials: K
authors.lastname: Harter
authors.forename: Jesús
authors.initials: J
authors.lastname: Vicente-Carbajosa
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Dröge-Laser
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000502:physiology*; D019281:Dimerization; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D009994:Osmolar Concentration; D011394:Proline Oxidase / Q000235:genetics / Q000502:physiology*; D011401:Promoter Regions, Genetic; D050436:Regulatory Elements, Transcriptional; D015533:Transcriptional Activation; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D011394:Proline Oxidase