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  • The EMBO Journal (2001) 20, 3917 - 3927
  • doi:10.1093/emboj/20.15.3917

X-ray structure of HPr kinase: a bacterial protein kinase with a P-loop nucleotide-binding domain

Sonia Fieulaine1, Solange Morera1, Sandrine Poncet2, Vicente Monedero2, Virginie Gueguen-Chaignon1, Anne Galinier3, Joël Janin1, Josef Deutscher2 and Sylvie Nessler1

  1. Laboratoire d'Enzymologie et Biochimie Structurales, UPR 9063, CNRS, 91198 Gif sur Yvette, France
  2. Laboratoire de Génétique des Microorganismes, CNRS URA 1925, INRA, 78850 Thiverval-Grignon, France
  3. Laboratoire de Chimie Bactérienne, UPR 9043, CNRS, 13402 Marseille cedex 20, France

Correspondence to:

Sylvie Nessler, E-mail: nessler@lebs.cnrs-gif.fr

Received 1 March 2001; Accepted 12 June 2001; Revised 11 June 2001

HPr kinase/phosphatase (HprK/P) is a key regulatory enzyme controlling carbon metabolism in Gram- positive bacteria. It catalyses the ATP-dependent phosphorylation of Ser46 in HPr, a protein of the phosphotransferase system, and also its dephosphorylation. HprK/P is unrelated to eukaryotic protein kinases, but contains the Walker motif A characteristic of nucleotide-binding proteins. We report here the X-ray structure of an active fragment of Lactobacillus casei HprK/P at 2.8 Å resolution, solved by the multiwavelength anomalous dispersion method on a seleniated protein (PDB code 1jb1). The protein is a hexamer, with each subunit containing an ATP-binding domain similar to nucleoside/nucleotide kinases, and a putative HPr-binding domain unrelated to the substrate-binding domains of other kinases. The Walker motif A forms a typical P-loop which binds inorganic phosphate in the crystal. We modelled ATP binding by comparison with adenylate kinase, and designed a tentative model of the complex with HPr based on a docking simulation. The results confirm that HprK/P represents a new family of protein kinases, first identified in bacteria, but which may also have members in eukaryotes.

  • Keywords:

    • catabolite repression,
    • HPr phosphorylation,
    • Lactobacillus casei,
    • P-loop,
    • protein kinase