An antioxidant redox system in the nucleus of wheat seed cells suffering oxidative stress

Pablo Pulido, Roland Cazalis, Francisco Javier Cejudo

    Research output: Contribution to journalArticle

    Abstract

    Cereal seed cells contain different mechanisms for protection against the oxidative stress that occurs during maturation and germination. One such mechanism is based on the antioxidant activity of a 1-Cys peroxiredoxin (1-Cys Prx) localized in the nuclei of aleurone and scutellum cells. However, nothing is known about the mechanism of activation of this enzyme. Here, we describe the pattern of localization of NADPH thioredoxin reductase (NTR) in developing and germinating wheat seeds using an immunocytochemical analysis. The presence of NTR in transfer cells, vascular tissue, developing embryo and root meristematic cells, agrees with the localization of thioredoxin h (Trx h), and supports the important function of the NTR/Trx system in cell proliferation and communication. Interestingly, NTR is found in the nuclei of seed cells suffering oxidative stress, thus showing co-localization with Trx h and 1-Cys Prx. To test whether the NTR/Trx system serves as a reductant of the 1-Cys Prx, we cloned a full-length cDNA encoding 1-Cys Prx from wheat, and expressed the recombinant protein in Escherichia coli. Using the purified components, we show NTR-dependent activity of the 1-Cys Prx. Mutants of the 1-Cys Prx allowed us to demonstrate that the peroxidatic residue of the wheat enzyme is Cys46, which is overoxidized in vitro under oxidant conditions. Analysis of extracts from developing and germinating seeds confirmed 1-Cys Prx overoxidation in vivo. Based on these results, we propose that NADPH is the source of the reducing power to regenerate 1-Cys Prx in the nuclei of seed cells suffering oxidative stress, in a process that is catalyzed by NTR. © 2008 The Authors.

    Original languageEnglish
    Pages (from-to)132-145
    Number of pages14
    JournalPlant Journal
    Volume57
    Issue number1
    DOIs
    Publication statusPublished - Jan 2009

    Keywords

    • Seeds
    • Peroxiredoxins
    • Triticum
    • Thioredoxin h
    • Antioxidants
    • Thioredoxin-Disulfide Reductase
    • Recombinant Proteins
    • Amino Acid Sequence
    • Cell Nucleus
    • Plant Proteins
    • Cloning, Molecular
    • NADP
    • Mutagenesis, Site-Directed
    • Oxidation-Reduction
    • DNA, Complementary
    • Sequence Alignment
    • Oxidative Stress
    • Escherichia coli
    • Molecular Sequence Data
    • RNA, Plant
    • Gene Expression Regulation, Plant

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