ATR3 encodes a diflavin reductase essential for Arabidopsis embryo development

Authors

  • Janani Varadarajan,

    1. Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-1155, USA
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  • Jocelyne Guilleminot,

    1. Laboratoire Génome et Développement des Plantes, UMR-CNRS-IRD 5096, Université de Perpignan Via Domitia 58 Avenue Paul Alduy, 66860 Perpignan-Cedex, France
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  • Claude Saint-Jore-Dupas,

    1. Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6037, IFRMP 23, UFR des Sciences, Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France
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  • Benoît Piégu,

    1. Laboratoire Génome et Développement des Plantes, UMR-CNRS-IRD 5096, Université de Perpignan Via Domitia 58 Avenue Paul Alduy, 66860 Perpignan-Cedex, France
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  • Marie-Edith Chabouté,

    1. Institut de Biologie Moléculaire des Plantes du CNRS, 12 rue du Général Zimmer, 67084 Strasbourg-Cedex, France
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  • Véronique Gomord,

    1. Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6037, IFRMP 23, UFR des Sciences, Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France
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  • Ronald C. Coolbaugh,

    1. Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-1155, USA
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  • Martine Devic,

    1. Laboratoire Génome et Développement des Plantes, UMR-CNRS-IRD 5096, Université de Perpignan Via Domitia 58 Avenue Paul Alduy, 66860 Perpignan-Cedex, France
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  • Valérie Delorme

    1. Laboratoire Génome et Développement des Plantes, UMR-CNRS-IRD 5096, Université de Perpignan Via Domitia 58 Avenue Paul Alduy, 66860 Perpignan-Cedex, France
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Author for correspondence:
Valérie Delorme
Tel: +33 4 6866 2242
Email: delorme@univ-perp.fr

Summary

  • The Arabidopsis genome possesses two confirmed Cytochrome P450 Reductase (CPR) genes, ATR1 and ATR2, together with a third putative homologue, ATR3, which annotation is questionable.
  • Phylogenetic analysis classified ATR3 as a CPR-like protein sharing homologies with the animal cytosolic dual flavin reductases, NR1 and Fre-1, distinct from the microsomal CPRs, ATR1 and ATR2. Like NR1 and Fre-1, ATR3 lacks the N-terminal endoplasmic reticulum (ER) anchor domain of CPRs and is localized in the cytoplasm. Recombinant ATR3 in plant soluble extracts was able to reduce cytochrome c but failed to reduce the human P450 CYP1A2.
  • Loss of ATR3 function resulted in early embryo lethality indicating that this reductase activity is essential. A yeast 2-hybrid screen identified a unique interaction of ATR3 with the homologue of the human anti-apoptotic CIAPIN1 and the yeast Dre2 protein.
  • This interaction suggests two possible roles for ATR3 in the control of cell death and in chromosome segregation at mitosis. Consistent with these results, the promoter of ATR3 is activated during cell cycle progression. Together these results demonstrated that ATR3 belongs to the NR1 subfamily of diflavin reductases whose characterized members are involved in essential cellular functions.

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