The Helicobacter pylori GroES Cochaperonin HspA Functions as a Specialized Nickel Chaperone and Sequestration Protein through Its Unique C-Terminal Extension

• DOI: 10.1128/jb.01216-09
• Publication Date: 2010-01-09T02:57:25Z
• Authors: Kristine Schauer; Cécile Muller; Marie Carrière; Agnès Labigne; Christine Cavazza; Hilde De Reuse
• Keywords: 0301 basic medicine; 570; Cytoplasm; [SDV]Life Sciences [q-bio]; MESH: Urease; Molecular Sequence Data; 610; MESH: Amino Acid Sequence; MESH: Heat-Shock Proteins; Mass Spectrometry; MESH: Protein Structure, Tertiary; 03 medical and health sciences; Bacterial Proteins; Hydrogenase; Nickel; MESH: Nickel; MESH: Protein Binding; Animals; Humans; Point Mutation; MESH: Animals; Amino Acid Sequence; MESH: Bacterial Proteins; Heat-Shock Proteins; MESH: Point Mutation; Sequence Deletion; MESH: Mass Spectrometry; MESH: Molecular Sequence Data; MESH: Humans; Helicobacter pylori; MESH: Cytoplasm; MESH: Sequence Deletion; Urease; Protein Structure, Tertiary; MESH: Protein Structure; MESH: Hydrogenase; MESH: Helicobacter pylori; Female; MESH: Molecular Chaperones; MESH: Female; Tertiary; Molecular Chaperones; Protein Binding

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.