Helicobacter pylori gene silencing in vivo demonstrates urease is essential for chronic infection.
Helicobacter pylori gene silencing in vivo demonstrates urease is essential for chronic infection.
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DOI：
10.1371/journal.ppat.1006464
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发表时间：
2017-06
期刊：
影响因子：
6.7
通讯作者：
Benghezal M
中科院分区：
文献类型：
--
作者：
Debowski AW;Walton SM;Chua EG;Tay AC;Liao T;Lamichhane B;Himbeck R;Stubbs KA;Marshall BJ;Fulurija A;Benghezal M
幽门螺杆菌感染引起慢性活动性胃炎，感染多年后可发展为消化性溃疡或胃腺癌。该细菌高度适应于在胃环境中存活，并且关键适应是毒力因子尿素酶。虽然广泛假设，但由于常规的脲酶敲除突变体不能定殖，因此持续感染的脲酶表达要求尚未通过实验阐明。为了克服这一限制，条件H。幽门螺杆菌尿素酶突变体是通过适应四环素诱导表达系统构建的，该系统能够在建立的感染期间改变细菌的尿素酶表型。通过严格的调控，我们证明了尿素酶的表达不仅是建立初始定植所需的，而且也是维持慢性感染所需的。此外，从晚期感染时间点成功分离tet逃逸突变体揭示了这种胃病原体持续表达尿素酶以维持慢性感染的强大选择性压力。除了条件基因表达系统中的突变外，还发现逃逸突变体在其他基因中存在变化，包括替代RNA聚合酶sigma因子fliA，突出了H. pylori适应变化的生态位。这里描述的tet系统为研究与H慢性期有关的基因提供了机会。pylori感染，以深入了解促进免疫逃逸和终身感染的细菌机制。此外，这种遗传工具还允许一种新的调查途径，以了解当细菌受到胁迫时，各种毒力决定因素在不断变化的生物环境中的重要性。幽门螺杆菌是一种细菌病原体，慢性感染全球一半的人口，是消化性溃疡和胃癌发展的主要因素。H.幽门螺杆菌已经进化到在胃中生存，一个重要的适应是尿素酶。没有这种酶，细菌不能在宿主中建立感染，尽管广泛假设，但由于常规脲酶突变体不能定殖，因此宿主慢性感染对脲酶的需求尚未进行实验测试。为了克服这一限制，引入了一种遗传系统，允许制造H。幽门螺杆菌菌株，其中尿素酶表达可以在细菌定殖胃后关闭。我们首次表明，这种酶不仅是重要的初始定植，但它也是非常重要的维持慢性感染。我们还表明，如果脲酶被关闭，细菌可以突变几个不同的基因，以恢复脲酶的表达。这里描述的遗传学方法为研究与H.幽门螺杆菌感染，以了解细菌如何能够避免免疫系统的清除，以及它如何能够适应不断变化的生物环境。
Helicobacter pylori infection causes chronic active gastritis that after many years of infection can develop into peptic ulceration or gastric adenocarcinoma. The bacterium is highly adapted to surviving in the gastric environment and a key adaptation is the virulence factor urease. Although widely postulated, the requirement of urease expression for persistent infection has not been elucidated experimentally as conventional urease knockout mutants are incapable of colonization. To overcome this constraint, conditional H. pylori urease mutants were constructed by adapting the tetracycline inducible expression system that enabled changing the urease phenotype of the bacteria during established infection. Through tight regulation we demonstrate that urease expression is not only required for establishing initial colonization but also for maintaining chronic infection. Furthermore, successful isolation of tet-escape mutants from a late infection time point revealed the strong selective pressure on this gastric pathogen to continuously express urease in order to maintain chronic infection. In addition to mutations in the conditional gene expression system, escape mutants were found to harbor changes in other genes including the alternative RNA polymerase sigma factor, fliA, highlighting the genetic plasticity of H. pylori to adapt to a changing niche. The tet-system described here opens up opportunities to studying genes involved in the chronic stage of H. pylori infection to gain insight into bacterial mechanisms promoting immune escape and life-long infection. Furthermore, this genetic tool also allows for a new avenue of inquiry into understanding the importance of various virulence determinants in a changing biological environment when the bacterium is put under duress. Helicobacter pylori is a bacterial pathogen that chronically infects half the global population and is a major contributor to the development of peptic ulcers and stomach cancer. H. pylori has evolved to survive in the stomach and one important adaptation is the enzyme urease. The bacteria cannot establish an infection in the host without this enzyme, and although widely postulated, the requirement of urease for chronic infection of the host has not been tested experimentally as conventional urease mutants are incapable of colonization. To overcome this constraint, a genetic system was introduced that allowed for the making of H. pylori strains in which urease expression could be turned off after the bacteria have colonised the stomach. We show for the first time that this enzyme is not only important for initial colonization but that it is also very important for maintaining chronic infection. We also show that if urease is turned off, the bacterium can mutate several different genes in order to restore urease expression. The genetic approach described here opens up opportunities to studying genes involved in the chronic stage of H. pylori infection to gain insight into how the bacterium is able to avoid clearance by the immune system and how it is able to adapt to changing biological environments.
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影响因子：
14.9
作者：
Haft DH;Selengut JD;Richter RA;Harkins D;Basu MK;Beck E
通讯作者：
Beck E
影响因子：
4.4
作者：
Fan, XJ;Gunasena, H;Reyes, VE
通讯作者：
Reyes, VE
影响因子：
3.1
作者：
Eaton, KA;Suerbaum, S;Krakowka, S
通讯作者：
Krakowka, S
影响因子：
5.1
作者：
Centlivre, M.;Zhou, X.;Legrand, N.
通讯作者：
Legrand, N.
DOI：
10.1038/88563
发表时间：
2001-06-01
期刊：
NATURE STRUCTURAL BIOLOGY
影响因子：
--
作者：
Ha, NC;Oh, ST;Oh, BH
通讯作者：
Oh, BH