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首页> 外文期刊>Journal of bacteriology >Helicobacter pylori rocF Is Required for Arginase Activity and Acid Protection In Vitro but Is Not Essential for Colonization of Mice or for Urease Activity
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Helicobacter pylori rocF Is Required for Arginase Activity and Acid Protection In Vitro but Is Not Essential for Colonization of Mice or for Urease Activity

机译：幽门螺杆菌rocF是精氨酸酶活性和体外酸保护所必需的，但对于小鼠定植或脲酶活性不是必需的

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Arginase of the Helicobacter pylori urea cycle hydrolyzes l-arginine to l-ornithine and urea.H. pylori urease hydrolyzes urea to carbon dioxide and ammonium, which neutralizes acid. Both enzymes are involved inH. pylori nitrogen metabolism. The roles of arginase in the physiology of H. pylori were investigated in vitro and in vivo, since arginase in H. pylori is metabolically upstream of urease and urease is known to be required for colonization of animal models by the bacterium. The H. pylori genehp1399, which is orthologous to the Bacillus subtilis rocF gene encoding arginase, was cloned, and isogenic allelic exchange mutants of three H. pylori strains were made by using two different constructs: 236-2 androcF::aphA3. In contrast to wild-type (WT) strains, all rocF mutants were devoid of arginase activity and had diminished serine dehydratase activity, an enzyme activity which generates ammonium. Compared with WT strain 26695 of H. pylori, the rocF::aphA3 mutant was ～1,000-fold more sensitive to acid exposure. The acid sensitivity of the rocF::aphA3 mutant was not reversed by the addition of l-arginine, in contrast to the WT, and yielded a ～10,000-fold difference in viability. Urease activity was similar in both strains and both survived acid exposure equally well when exogenous urea was added, indicating that rocF is not required for urease activity in vitro. Finally, H. pylorimouse-adapted strain SS1 and the 236-2 rocF isogenic mutant colonized mice equally well: 8 of 9 versus 9 of 11 mice, respectively. However, the rocF::aphA3 mutant of strain SS1 had moderately reduced colonization (4 of 10 mice). The geometric mean levels of H. pylori recovered from these mice (in log10 CFU) were 6.1, 5.5, and 4.1, respectively. Thus,H. pylori rocF is required for arginase activity and is crucial for acid protection in vitro but is not essential for in vivo colonization of mice or for urease activity.
机译：幽门螺杆菌尿素循环的精氨酸酶将l-精氨酸水解为l-鸟氨酸和尿素。幽门螺杆菌尿素酶将尿素水解为二氧化碳和铵，从而中和酸。两种酶都参与emH。幽门螺杆菌氮代谢精氨酸酶在 H的生理中的作用。由于在 H中存在精氨酸酶，因此已在体外和体内研究了幽门螺旋杆菌。幽门螺杆菌在尿素酶的代谢上游，已知尿素酶是细菌在动物模型中定殖所必需的。 H。克隆了与编码精氨酸酶的枯草芽孢杆菌rocF 基因同源的幽门螺杆菌基因 hp1399 ，并克隆了三个 H的等位基因交换突变体。幽门螺杆菌菌株是使用两种不同的构建体：236-2和 rocF :: aphA3 构建的。与野生型（WT）菌株相反，所有 rocF 突变体都没有精氨酸酶活性，而丝氨酸脱水酶活性却降低了，后者是一种产生铵的酶。与 H的WT菌株26695相比。 pylori （rocF :: aphA3 突变体）对酸暴露的敏感性高约1000倍。与WT相比， rocF :: aphA3 突变体的酸敏感性不能通过添加l-精氨酸来逆转，其生存力差异约为10,000倍。两种菌株中的脲酶活性相似，当添加外源脲时，两种酶在酸暴露下均能很好地存活，这表明 rocF 并不是体外脲酶活性所必需的。最后， H。幽门螺杆菌小鼠适应株SS1和236-2 rocF 等基因突变小鼠定植得很好：分别为9只小鼠中的8只和11只小鼠中的9只。但是，菌株SS1的 rocF :: aphA3 突变体的定居程度有所降低（10只小鼠中有4只）。 H的几何平均水平。从这些小鼠中回收的幽门螺杆菌（log 10 CFU）分别为6.1、5.5和4.1。因此， H。幽门螺杆菌rocF 是精氨酸酶活性所必需的，对于体外酸保护至关重要，但对于小鼠体内定植或脲酶活性不是必需的。

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