title: The novel Helicobacter pylori CznABC metal efflux pump is required for cadmium, zinc, and nickel resistance, urease modulation, and gastric colonization.
abstract: Maintaining metal homeostasis is crucial for the adaptation of Helicobacter pylori to the gastric environment. Iron, copper, and nickel homeostasis has recently been demonstrated to be required for the establishment of H. pylori infection in animal models. Here we demonstrate that the HP0969-0971 gene cluster encoding the Czc-type metal export pump homologs HP0969, HP0970, and the H. pylori-specific protein HP0971 forms part of a novel H. pylori metal resistance determinant, which is required for gastric colonization and for the modulation of urease activity. Insertional mutagenesis of the HP0971, HP0970, or HP0969 genes in H. pylori reference strain 26695 resulted in increased sensitivity to cadmium, zinc, and nickel (czn), suggesting that the encoded proteins constitute a metal-specific export pump. Accordingly, the genes were designated cznC (HP0971), cznB (HP0970), and cznA (HP0969). The CznC and CznA proteins play a predominant role in nickel homeostasis, since only the cznC and cznA mutants but not the cznB mutant displayed an 8- to 10-fold increase in urease activity. Nickel-specific affinity chromatography demonstrated that recombinant versions of CznC and CznB can bind to nickel and that the purified CznB protein interacted with cadmium and zinc, since both metals competitively inhibited nickel binding. Finally, single cznA, cznB, and cznC mutants did not colonize the stomach in a Mongolian gerbil-based animal model. This demonstrates that the metal export functions of H. pylori cznABC are essential for gastric colonization and underlines the extraordinary importance of metal ion homeostasis for the survival of H. pylori in the gastric environment.
authors.affiliation: Department of Microbiology and Hygiene, Institute of Medical Microbiology and Hygiene, University Hospital Freiburg, Hermann-Herder-Str. 11, D-79104 Freiburg, Germany. frank_staehler@web.de
authors.forename: Frank Nils
authors.initials: FN
authors.lastname: Stähler
authors.forename: Stefan
authors.initials: S
authors.lastname: Odenbreit
authors.forename: Rainer
authors.initials: R
authors.lastname: Haas
authors.forename: Julia
authors.initials: J
authors.lastname: Wilrich
authors.forename: Arnoud H M
authors.initials: AH
authors.lastname: Van Vliet
authors.forename: Johannes G
authors.initials: JG
authors.lastname: Kusters
authors.forename: Manfred
authors.initials: M
authors.lastname: Kist
authors.forename: Stefan
authors.initials: S
authors.lastname: Bereswill
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002104:Cadmium / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000502:physiology*; D005753:Gastric Mucosa / Q000382:microbiology*; D005849:Gerbillinae; D016481:Helicobacter Infections / Q000378:metabolism / Q000382:microbiology; D016480:Helicobacter pylori / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity; D009154:Mutation; D009532:Nickel / Q000378:metabolism*; D014510:Urease / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins; C512594:CznA protein, Helicobacter pylori; C512595:CznB protein, Helicobacter pylori; C512596:CznC protein, Helicobacter pylori; D002104:Cadmium; D009532:Nickel; D014510:Urease; D015032:Zinc