Open AccessThe Helicobacter pylori GroES Cochaperonin HspA Functions as a Specialized Nickel Chaperone and Sequestration Protein through Its Unique C-Terminal Extension
Author(s) -
Kristine Schauer,
Cécile Muller,
Marie Carrière,
Agnès Labigne,
Christine Cavazza,
Hilde De Reuse
Publication year - 2010
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.01216-09
Subject(s) - hydrogenase , chaperone (clinical) , groes , biology , helicobacter pylori , mutant , nickel , urease , biochemistry , heat shock protein , intracellular , groel , enzyme , chemistry , escherichia coli , gene , genetics , medicine , organic chemistry , pathology
The transition metal nickel plays a central role in the human gastric pathogenHelicobacter 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 nickelin vitro . To investigate the function of this extension inH. 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 thatH. 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.