Karita M, Tsuda M, Nakazawa T
First Department of Internal Medicine, Yamaguchi University, Japan.
J Clin Gastroenterol. 1995;21 Suppl 1:S160-3.
To determine the role of urease in colonization of Helicobacter pylori, we constructed a Ure- mutant by allelic exchange mutagenesis and examined the characteristics of the Ure- mutant and its parental strain. We also evaluated whether both strains would be able to colonize the stomach of nude mice. Kmr transformants obtained showed the Ure- phenotype, and one transformant, HPT73, was established as a knock-out mutant of the ureB gene by Southern analysis. Except for the null activity of the urease, HPT73 showed no difference from its parental strain, CPY3401, in growth rate in liquid medium, production of cytotoxin, and motility. However, CPY3401 had more acid resistance than HPT73. Moreover, CPY3401, but not HPT73, was detected in the nude mouse stomach. In the presence of HRA, both CPY3401 and HPT73 colonized the stomachs of nude mice. In summary, H. pylori requires urease for colonization in vivo and its survival under the acidic conditions of the stomach.
为了确定脲酶在幽门螺杆菌定植中的作用，我们通过等位基因交换诱变构建了一个脲酶缺陷型突变体，并研究了该突变体及其亲本菌株的特性。我们还评估了这两种菌株是否都能在裸鼠胃中定植。获得的卡那霉素抗性转化子表现出脲酶缺陷型表型，通过Southern分析确定其中一个转化子HPT73为ureB基因的敲除突变体。除了脲酶无活性外，HPT73在液体培养基中的生长速率、细胞毒素产生和运动性方面与其亲本菌株CPY3401没有差异。然而，CPY3401比HPT73具有更强的耐酸性。此外，在裸鼠胃中检测到了CPY3401，但未检测到HPT73。在含有组胺的条件下，CPY3401和HPT73都能在裸鼠胃中定植。总之，幽门螺杆菌在体内定植及其在胃酸性条件下的存活需要脲酶。
