Basis of recognition between the NarJ chaperone and the N-terminus of the NarG subunit from Escherichia coli nitrate reductase

Authors

  • Silva Zakian,

    1.  Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France
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  • Daniel Lafitte,

    1.  MaP site Timone, UMR INSERM 911, Université d’Aix-Marseille II, France
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  • Alexandra Vergnes,

    1.  Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France
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  • Cyril Pimentel,

    1.  Interactions et Modulateurs de Réponses, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France
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  • Corinne Sebban-Kreuzer,

    1.  Interactions et Modulateurs de Réponses, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France
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  • René Toci,

    1.  Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France
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  • Jean-Baptiste Claude,

    1.  Information Génomique et Structurale, Marseille, France
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  • Françoise Guerlesquin,

    1.  Interactions et Modulateurs de Réponses, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France
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  • Axel Magalon

    1.  Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France
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A. Magalon, Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, 31, chemin Joseph Aiguier 13402 Marseille Cedex 09, France
Fax: +33 491 718 914
Tel: +33 491 164 668
E-mail: magalon@ifr88.cnrs-mrs.fr

Abstract

A novel class of molecular chaperones co-ordinates the assembly and targeting of complex metalloproteins by binding to an amino-terminal peptide of the cognate substrate. We have previously shown that the NarJ chaperone interacts with the N-terminus of the NarG subunit coming from the nitrate reductase complex, NarGHI. In the present study, NMR structural analysis revealed that the NarG(1–15) peptide adopts an α-helical conformation in solution. Moreover, NarJ recognizes and binds the helical NarG(1–15) peptide mostly via hydrophobic interactions as deduced from isothermal titration calorimetry analysis. NMR and differential scanning calorimetry analysis revealed a modification of NarJ conformation during complex formation with the NarG(1–15) peptide. Isothermal titration calorimetry and BIAcore experiments support a model whereby the protonated state of the chaperone controls the time dependence of peptide interaction.

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