title: The Helicobacter pylori GroES cochaperonin HspA functions as a specialized nickel chaperone and sequestration protein through its unique C-terminal extension.
abstract: The transition metal nickel plays a central role in the human gastric pathogen Helicobacter pylori because it is required for two enzymes indispensable for colonization, the nickel metalloenzyme urease and [NiFe] hydrogenase. To sustain nickel availability for these metalloenzymes while providing protection from the metal's harmful effects, H. pylori is equipped with several specific nickel-binding proteins. Among these, H. pylori possesses a particular chaperone, HspA, that is a homolog of the highly conserved and essential bacterial heat shock protein GroES. HspA contains a unique His-rich C-terminal extension and was demonstrated to bind nickel in vitro. To investigate the function of this extension in H. pylori, we constructed mutants carrying either a complete deletion or point mutations in critical residues of this domain. All mutants presented a decreased intracellular nickel content measured by inductively coupled plasma mass spectrometry (ICP-MS) and reduced nickel tolerance. While urease activity was unaffected in the mutants, [NiFe] hydrogenase activity was significantly diminished when the C-terminal extension of HspA was mutated. We conclude that H. pylori HspA is involved in intracellular nickel sequestration and detoxification and plays a novel role as a specialized nickel chaperone involved in nickel-dependent maturation of hydrogenase.
authors.affiliation: Institut Pasteur, Unité Postulante Pathogenèse de Helicobacter, 28, rue du Docteur Roux, 75724 Paris Cedex 15, France.
authors.forename: Kristine
authors.initials: K
authors.lastname: Schauer
authors.forename: Cécile
authors.initials: C
authors.lastname: Muller
authors.forename: Marie
authors.initials: M
authors.lastname: Carrière
authors.forename: Agnès
authors.initials: A
authors.lastname: Labigne
authors.forename: Christine
authors.initials: C
authors.lastname: Cavazza
authors.forename: Hilde
authors.initials: H
authors.lastname: De Reuse
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000737:chemistry; D005260:Female; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D016480:Helicobacter pylori / Q000378:metabolism*; D006801:Humans; D006864:Hydrogenase / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D018832:Molecular Chaperones / Q000378:metabolism*; D008969:Molecular Sequence Data; D009532:Nickel / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D014510:Urease / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; C113725:HspA protein, bacteria; D018832:Molecular Chaperones; D009532:Nickel; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D014510:Urease