FpvA bound to non-cognate pyoverdines: molecular basis of siderophore recognition by an iron transporter

Authors

  • Jason Greenwald,

    Corresponding author
    1. Laboratoire de Biologie Structurale des Membranes and
      *E-mail jason.greenwald@phys.chem.ethz.ch; Tel. (+41) 446334924; Fax (+41) 446321021.
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    • Present address: ETH Zürich, Laboratorium für Physikalische Chemie, HCl F 228, Wolfgang-Paul Str. 10, 8093 Zürich, Switzerland;

  • Mirella Nader,

    1. Laboratoire Métaux et Microorganismes, Département Récepteurs et Protéines Membranaires, UMR7175, École Supérieure de Biotechnologie de Strasbourg, Bd Sébastien Brant, BP10413, 67412 Illkirch, France.
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  • Hervé Celia,

    1. Laboratoire Métaux et Microorganismes, Département Récepteurs et Protéines Membranaires, UMR7175, École Supérieure de Biotechnologie de Strasbourg, Bd Sébastien Brant, BP10413, 67412 Illkirch, France.
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    • Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027 CNRS, 31 chemin Joseph Aiguier, 13402 Marseille, France.

  • Christelle Gruffaz,

    1. Université de Strasbourg, Génétique Moléculaire, Génomique, Microbiologie, UMR 7156, 28 rue Goethe, 67000 Strasbourg, France.
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  • Valérie Geoffroy,

    1. Laboratoire Métaux et Microorganismes, Département Récepteurs et Protéines Membranaires, UMR7175, École Supérieure de Biotechnologie de Strasbourg, Bd Sébastien Brant, BP10413, 67412 Illkirch, France.
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  • Jean-Marie Meyer,

    1. Université de Strasbourg, Génétique Moléculaire, Génomique, Microbiologie, UMR 7156, 28 rue Goethe, 67000 Strasbourg, France.
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  • Isabelle J. Schalk,

    1. Laboratoire Métaux et Microorganismes, Département Récepteurs et Protéines Membranaires, UMR7175, École Supérieure de Biotechnologie de Strasbourg, Bd Sébastien Brant, BP10413, 67412 Illkirch, France.
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  • Franc Pattus

    1. Laboratoire de Biologie Structurale des Membranes and
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*E-mail jason.greenwald@phys.chem.ethz.ch; Tel. (+41) 446334924; Fax (+41) 446321021.

Summary

The first step in the specific uptake of iron via siderophores in Gram-negative bacteria is the recognition and binding of a ferric siderophore by its cognate receptor. We investigated the molecular basis of this event through structural and biochemical approaches. FpvA, the pyoverdine–Fe transporter from Pseudomonas aeruginosa ATCC 15692 (PAO1 strain), is able to transport ferric–pyoverdines originating from other species, whereas most fluorescent pseudomonads are only able to use the one they produce among the more than 100 known different pyoverdines. We solved the structure of FpvA bound to non-cognate pyoverdines of high- or low-affinity and found a close correlation between receptor–ligand structure and the measured affinities. The structure of the first amino acid residues of the pyoverdine chain distinguished the high- and low-affinity binders while the C-terminal portion of the pyoverdines, often cyclic, does not appear to contribute extensively to the interaction between the siderophore and its transporter. The specificity of the ferric–pyoverdine binding site of FpvA is conferred by the structural elements common to all ferric–pyoverdines, i.e. the chromophore, iron, and its chelating groups.

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