title: Mutational analysis of the Helicobacter pylori carbonic anhydrases.
abstract: In the gastric microenvironment, Helicobacter pylori is exposed to bicarbonate, urea and acid. Here it is demonstrated that both H. pylori carbonic anhydrases (CAs) are required for maintaining urease activity and therefore influence H. pylori urea resistance at neutral pH. Furthermore, the beta-CA is required for acid resistance as indicated by a growth defect of the corresponding mutant at low pH. The alpha- and beta-CA mutants as well as the double mutant were more resistant to bicarbonate, indicating that both enzymes are involved in bicarbonate metabolism. These phenotypes support important CA-functions in H. pylori urea and bicarbonate metabolism and acid resistance. Thus, both CA enzymes might be required for survival in the gastric niche.
authors.affiliation: Institute of Medical Microbiology and Hygiene, Department of Microbiology and Hygiene, University Hospital Freiburg, Hermann-Herder-Strasse 11, D-79104 Freiburg, Germany. frank.staehler@uniklinik-freiburg.de
authors.forename: Frank Nils
authors.initials: FN
authors.lastname: Stähler
authors.forename: Lynn
authors.initials: L
authors.lastname: Ganter
authors.forename: Kathrin
authors.initials: K
authors.lastname: Lederer
authors.forename: Manfred
authors.initials: M
authors.lastname: Kist
authors.forename: Stefan
authors.initials: S
authors.lastname: Bereswill
mesh_terms: D001639:Bicarbonates / Q000378:metabolism / Q000494:pharmacology; D002256:Carbonic Anhydrases / Q000235:genetics* / Q000378:metabolism*; D003470:Culture Media; D024881:Drug Resistance, Bacterial; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D014508:Urea / Q000378:metabolism / Q000494:pharmacology; D014510:Urease / Q000378:metabolism
chemical_list: D001639:Bicarbonates; D003470:Culture Media; D014508:Urea; D014510:Urease; D002256:Carbonic Anhydrases