Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Yonsei Med J. 2010 Jan;51(1):39-44. doi: 10.3349/ymj.2010.51.1.39. Epub 2009 Dec 29.
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.
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.
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.
The results of this study showed that fur appears to be involved in acid resistant H. pylori urease activity.
铁摄取调节因子（FUR）在幽门螺杆菌（H. pylori）的耐酸性中的作用被认为与尿素酶无关。然而，本研究表明 Fur 影响尿素酶活性。
通过用卡那霉素抗性标记基因替换 Fur 基因，构建了 H. pylori 的 Fur 敲除突变体。比较了野生型 H. pylori 和 fur 突变体的存活情况。使用膜通透性和非通透性荧光 DNA 探针通过共聚焦显微镜评估细菌内膜的完整性。在 pH 3 至 8 之间测量完整 H. pylori 的尿素酶活性。对两种菌株进行 ureI、ureE、ureF、ureG 和 ureH 等尿素酶基因的实时 PCR。
fur 缺失影响 H. pylori 在 pH 4 下的存活。完整 fur 突变体的尿素酶活性曲线与野生型相似，但在 pH 小于 5 时比野生型低 3 倍。实时 PCR 显示所有基因在 fur 突变体中的表达均一致下调。
本研究结果表明，fur 似乎参与了耐酸 H. pylori 尿素酶活性。
