Yonsei Med J.  2010 Jan;51(1):39-44. 10.3349/ymj.2010.51.1.39.

Helicobacter pylori Urease Activity is Influenced by Ferric Uptake Regulator

• Lee JS
• Choe YH
• Lee JH
• Lee HJ
• Lee JH
• Choi YO

• KMID: 1779604
• DOI: http://doi.org/10.3349/ymj.2010.51.1.39

Abstract

PURPOSE
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. MATERIALS AND 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. CONCLUSION: The results of this study showed that fur appears to be involved in acid resistant H. pylori urease activity.

Keyword

Helicobacter pylori; fur protein; gene knockout; urease; acid resistance

MeSH Terms

Bacterial Proteins/genetics/*physiology
Helicobacter pylori/*enzymology/genetics
Hydrogen-Ion Concentration
Microscopy, Confocal
Models, Biological
Mutation
Repressor Proteins/genetics/*physiology
Urease/*metabolism

Figure

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  Fig. 1 The previously known relationship of NikR, Fur, amidase, and urease in H. pylori, suggested by van Vliet5. Our new suggestion is demonstrated by the arrow linked with a question mark.

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  Fig. 2 Survival of H. pylori wild strain and furKO mutant at pH 4.0. WT, wild type; KO, fur knockout mutant.

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  Fig. 3 Urease activity of intact H. pylori. furKO, fur knockout mutant.

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  Fig. 4 Real-time qPCR. furKO, fur knockout mutant.

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