Helicobacter pylori urease activity is influenced by ferric uptake regulator.
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.
Lee
Jong Seung
JS
Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Choe
Yon Ho
YH
Lee
Ji Hyuk
JH
Lee
Hye Jin
HJ
Lee
Jee Hyun
JH
Choi
Young Ok
YO
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*
D001426:Bacterial Proteins; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D014510:Urease