title: Activities of urease and nickel uptake of Helicobacter pylori proteins are media- and host-dependent.
abstract: BACKGROUND
  Nickel-dependent urease activity and nickel supply are essential for successful colonization of Helicobacter pylori in the acidic environment of the human stomach. A comparison of media effects on these two activities have never been carried out. Additionally to H. pylori we cultivated an Escherichia coli strain expressing the urease and the nickel transporter NixA of H. pylori on the same four media and measured in all cases urease and nickel uptake activity.
  
  
  OBJECTIVE
  To compare nickel uptake and urease activity on an inter- and intraspecies level.
  
  
  RESULTS
  In H. pylori nickel uptake (four to 200 times) and urease activities (400 to 30,000 times) were found to be much higher in comparison to the tested E. coli strain after growth on all media. These differences could not be explained by reduced protein amounts in the heterologous host E. coli. On which media the two bacteria extracted most of the nickel were organism-dependent: E. coli on Brucella Broth, H. pylori on Trypticase Soy Broth, and Minimal Media.
  
  
  CONCLUSIONS
  H. pylori took nickel much more efficiently up than E. coli. The observed differences in urease activity are most likely due to additional protein components absent in the recombinant E. coli strain. The observed variety in nickel uptake and urease activities on the different media in the same organism depended on the intrinsic nickel content and chelating capacities of media components. Different culture conditions may lead to varying results; generalizations should be concluded only after excluding their media dependence.
authors.affiliation: Department of Internal Medicine, Clinic of Gastroenterology and Hepatology, University Hospital of Zurich, Zurich, Switzerland.
authors.forename: Lutz
authors.initials: L
authors.lastname: Wolfram
authors.forename: Peter
authors.initials: P
authors.lastname: Bauerfeind
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D003470:Culture Media / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D016480:Helicobacter pylori / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D009532:Nickel / Q000378:metabolism*; D014510:Urease / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D009532:Nickel; D014510:Urease