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首页> 外文期刊>Infection and immunity >Characteristics of Helicobacter pylori variants selected for urease deficiency.
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Characteristics of Helicobacter pylori variants selected for urease deficiency.

机译：针对尿素酶缺乏症而选择的幽门螺杆菌变异体的特征。

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The urease of Helicobacter pylori is suspected to play a role in the pathogenesis of gastritis. Although all clinical isolates of H. pylori are urease positive (U+), we have selected and characterized several spontaneously arising urease-negative (U-) variants from wild-type strain 60190. Urease-negative variants were identified by growth in medium containing 60 mM urea and arose at a frequency of 10(-5) to 10(-6). The urease activity of the wild-type strain inhibited growth of this strain in the presence of 60 mM urea. U- variants retained the U- phenotype for more than 100 passages on medium with or without urea. The urease activities of the original U+ and derived U- cells were 9.55 to 16.7 and 0.01 to 0.17 U/mg of protein, respectively. Colonial growth and other biochemical characteristics were identical for the strains. U- variants showed three classes of whole-cell sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles: (i) identical to U+; (ii) change in the migration of the 61-kDa urease subunit; and (iii) lack of 61- and 30-kDa subunits. These differences were confirmed by immunoblotting and by protein separation using fast protein liquid chromatography. The U+ strain but not U- variants tolerated exposure to pH 4.0 for 60 min in the presence of urea. Supernatants of the U+ strain and U- variants contained vacuolating cytotoxin activity for HeLa cells in similar titers. By enzyme-linked immunosorbent assay, human serum samples recognized water extract from the U+ strain significantly better than extract from a U- variant lacking urease subunits. In conclusion, this study demonstrates that U- H. pylori variants may arise spontaneously, that urease activity enhances survival at acid pH, and that urease and cytotoxin activities are disparate phenotypes.
机译：幽门螺杆菌的脲酶被怀疑在胃炎的发病机理中起作用。尽管所有幽门螺杆菌临床分离株均为脲酶阳性（U +），但我们已从野生型菌株60190中选择并鉴定了一些自发产生的脲酶阴性（U-）变体。通过在含有60的培养基中生长鉴定了脲酶阴性变体mM尿素以10（-5）至10（-6）的频率出现。在60mM尿素的存在下，野生型菌株的脲酶活性抑制了该菌株的生长。在有或没有尿素的培养基上，U-变体保留U-表型100次以上。原始U +和衍生U-细胞的脲酶活性分别为9.55-16.7和0.01-0.17 U / mg蛋白质。菌株的菌落生长和其他生化特性相同。 U-变体显示三类全细胞十二烷基硫酸钠-聚丙烯酰胺凝胶电泳图谱：（i）与U +相同; （ii）61 kDa脲酶亚基迁移的变化; （iii）缺乏61和30 kDa的亚基。通过免疫印迹和使用快速蛋白质液相色谱的蛋白质分离可以确认这些差异。在存在尿素的情况下，U +菌株但不耐受U-变体，使其在pH 4.0下暴露60分钟。 U +菌株和U-变体的上清液以相似的滴度包含对HeLa细胞的空化细胞毒素活性。通过酶联免疫吸附测定，人血清样品识别出来自U +菌株的水提取物明显优于来自缺乏脲酶亚基的U-变体的提取物。总之，这项研究表明幽门螺杆菌变种可能自发出现，脲酶活性提高了在酸性pH下的存活率，而脲酶和细胞毒素的活性却是不同的表型。

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