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Analysis of the proteins targeted by CDSP32, a plastidic thioredoxin participating in oxidative stress responses

Authors

  • Pascal Rey,

    Corresponding author
    1. CEA/Cadarache, DSV, DEVM, Laboratoire d'Ecophysiologie de la Photosynthèse, 13108 Saint-Paul-lez-Durance Cedex, France,
      (fax +33 4 42 25 62 65; e-mail pascal.rey@cea.fr).
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  • Stéphan Cuiné,

    1. CEA/Cadarache, DSV, DEVM, Laboratoire d'Ecophysiologie de la Photosynthèse, 13108 Saint-Paul-lez-Durance Cedex, France,
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  • Françoise Eymery,

    1. CEA/Cadarache, DSV, DEVM, Laboratoire d'Ecophysiologie de la Photosynthèse, 13108 Saint-Paul-lez-Durance Cedex, France,
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  • Jérome Garin,

    1. CEA/Grenoble, Laboratoire de Chimie des Protéines, ERM CEA/INSERM 0201, 17, rue des Martyrs, 38054 Grenoble Cedex 9, France, and
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  • Magali Court,

    1. CEA/Grenoble, Laboratoire de Chimie des Protéines, ERM CEA/INSERM 0201, 17, rue des Martyrs, 38054 Grenoble Cedex 9, France, and
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  • Jean-Pierre Jacquot,

    1. UMR 1136, Interaction Arbres Microorganismes, Institut National de la Recherche Agronomique, Université Nancy I Henri Poincaré, 54506 Vandoeuvre Cedex, France
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  • Nicolas Rouhier,

    1. UMR 1136, Interaction Arbres Microorganismes, Institut National de la Recherche Agronomique, Université Nancy I Henri Poincaré, 54506 Vandoeuvre Cedex, France
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  • Mélanie Broin

    1. CEA/Cadarache, DSV, DEVM, Laboratoire d'Ecophysiologie de la Photosynthèse, 13108 Saint-Paul-lez-Durance Cedex, France,
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(fax +33 4 42 25 62 65; e-mail pascal.rey@cea.fr).

Summary

The chloroplastic drought-induced stress protein of 32 kDa (CDSP32) is a thioredoxin induced by environmental stress conditions. To gain insight into the function of CDSP32, we applied two strategies to analyze its targets. First, using affinity chromatography with an immobilized CDSP32 active site mutant, we identified six plastidic targets of CDSP32. Three of them are involved in photosynthetic processes: ATP-ase γ-subunit, Rubisco and aldolase. The three others participate in the protection against oxidative damage: two peroxiredoxins, PrxQ and the BAS1 2-Cys peroxiredoxin, and a B-type methionine sulfoxide reductase. Then, we developed a novel strategy to trap targets directly in leaf extracts. The method, based on co-immunoprecipitation using extracts from plants overexpressing Wt CDSP32 or CDSP32 active site mutant, confirmed the interaction in vivo between CDSP32 and the PrxQ and BAS1 peroxiredoxins. We showed that CDSP32 is able to form heterodimeric complexes with PrxQ and that the peroxiredoxin displays CDSP32-dependent peroxidase activity. Under photooxidative stress induced by methyl viologen, plants overexpressing CDSP32 active site mutant exhibit decreased maximal PSII photochemical efficiency and retain much less chlorophyll compared with Wt plants and with plants overexpressing Wt CDSP32. We propose that the increased sensitivity results from trapping in planta of the targets involved in the protection against oxidative damage. We conclude that CDSP32, compared with other plant thioredoxins, is a thioredoxin more specifically involved in plastidic responses against oxidative stress.

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