title: Helicobacter pylori urease activity is influenced by ferric uptake regulator.
abstract: OBJECTIVE
  The role of the Ferric Uptake Regulator (FUR) in the acid resistance of Helicobacter pylori (H. pylori) has been thought to be independent of urease. However, we demonstrated in this study that Fur influences urease activity.
  
  
  METHODS
  A fur knockout mutant of H. pylori was constructed by replacing the Fur gene with a kanamycin resistant marker gene. The wild-type H. pylori and fur mutant were compared for survival. The integrity of the inner membrane of the bacteria was evaluated by confocal microscopy using membrane-permeant and -impermeant fluorescent DNA probes. Urease activity of intact H. pylori was measured between pH 3 and 8. Real time PCR of both strains was performed for urease genes including ureI, ureE, ureF, ureG, and ureH.
  
  
  RESULTS
  The fur deletion affected the survival of H. pylori at pH 4. The urease activity curve of the intact fur mutant showed the same shape as the wild-type but was 3-fold lower than the wild-type at a pH of less than 5. Real time PCR revealed that the expression of all genes was consistently down-regulated in the fur mutant.
  
  
  CONCLUSIONS
  The results of this study showed that fur appears to be involved in acid resistant H. pylori urease activity.
authors.affiliation: Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jong Seung
authors.initials: JS
authors.lastname: Lee
authors.forename: Yon Ho
authors.initials: YH
authors.lastname: Choe
authors.forename: Ji Hyuk
authors.initials: JH
authors.lastname: Lee
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Lee
authors.forename: Jee Hyun
authors.initials: JH
authors.lastname: Lee
authors.forename: Young Ok
authors.initials: YO
authors.lastname: Choi
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D018613:Microscopy, Confocal; D008954:Models, Biological; D009154:Mutation; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D014510:Urease / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D014510:Urease