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Article

  • The EMBO Journal (2006) 25, 3133 - 3143
  • doi:10.1038/sj.emboj.7601206

Published online: 29 June 2006

Combinatorial control of Arabidopsis proline dehydrogenase transcription by specific heterodimerisation of bZIP transcription factors

Fridtjof Weltmeier1,a, Andrea Ehlert1,a, Caroline S Mayer1, Katrin Dietrich1, Xuan Wang1, Katia Schütze2, Rosario Alonso3, Klaus Harter2, Jesús Vicente-Carbajosa3 and Wolfgang Dröge-Laser1

  1. Albrecht-von-Haller Institut, Universität Göttingen, Göttingen, Germany
  2. Zentrum für Molekularbiologie der Pflanzen, Pflanzenphysiologie, Tübingen, Germany
  3. Department of Bioquimica y Biologia Molecular, ETSI Agronomos, Universidad Politecnica, Ciudad Universitaria, Madrid, Spain

Correspondence to:

Wolfgang Dröge-Laser, Albrecht-von-Haller Institut, University of Götiingen, Untere Karspüle 2, Göttingen 37073, Germany. Tel.: +49 (0)551 39 19816; Fax: +49 (0)551 39 7820; E-mail: wdroege@gwdg.de

aThese authors contributed equally to this work

Received 19 December 2005; Accepted 30 May 2006

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.

  • Keywords:

    • Arabidopsis thaliana,
    • bZIP transcription factors,
    • heterodimerisation,
    • hypo-osmolarity response,
    • ProDH transcription