title: pH-dependent protein profiles of Helicobacter pylori analyzed by two-dimensional gels.
abstract: BACKGROUND
  Helicobacter pylori survives transient exposure to extreme acid prior to adherence and growth on the gastric epithelium at neutral pH.
  
  
  METHODS
  The effect of pH stress on protein profiles of H. pylori was observed using two-dimensional gel electrophoresis (2-D gels). H. pylori 26695 was grown microaerobically in tryptone-yeast extract broth, 3% fetal bovine serum. Growth in acid alkalinized the medium, whereas growth in base caused acidification. For 2-D gel analysis of protein profiles, cultures were grown in media buffered at pH 5.7 and at pH 7.5.
  
  
  RESULTS
  Under all pH conditions, the most abundant proteins observed were the urease structural subunit UreB and the chaperonin GroEL. Growth in acid significantly increased the abundance of UreB. Thus, urease expression is not completely constitutive, as reported previously, but shows regulation by pH. Another protein observed only at low pH was identified as mammalian apolipoprotein A-I, possibly taken up by H. pylori from bovine serum in the growth medium. This finding, if confirmed, suggests that uptake of high-density lipoprotein from the human host may facilitate acquisition of cholesterol, required for formation of the unique cholesteryl glucosides in the membrane of H. pylori. In growth above pH 7, three stress proteins were induced: GroES (HspA), GroEL (HspB), and the antioxidant AhpC homolog TsaA. In addition, N-terminal sequence analysis identified five additional proteins that had not previously been reported on 2-D gels of H. pylori (FMN, SodB, TrxB, TsaA, and Tsr).
  
  
  CONCLUSIONS
  In summary, our 2-D gel study reveals expression of several proteins dependent on growth pH.
authors.affiliation: Department of Biology, Kenyon College, Gambier, OH 43022, USA. slonczewki@kenyon.edu
authors.forename: J L
authors.initials: JL
authors.lastname: Slonczewski
authors.forename: D J
authors.initials: DJ
authors.lastname: McGee
authors.forename: J
authors.initials: J
authors.lastname: Phillips
authors.forename: C
authors.initials: C
authors.lastname: Kirkpatrick
authors.forename: H L
authors.initials: HL
authors.lastname: Mobley
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis*; D003470:Culture Media; D015180:Electrophoresis, Gel, Two-Dimensional; D016480:Helicobacter pylori / Q000737:chemistry* / Q000254:growth & development*; D006863:Hydrogen-Ion Concentration
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media