Functional analysis of the Helicobacter pylori cag pathogenicity island reveals both VirD4-CagA-dependent and VirD4-CagA-independent mechanisms
Functional analysis of the Helicobacter pylori cag pathogenicity island reveals both VirD4-CagA-dependent and VirD4-CagA-independent mechanisms
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DOI：
10.1128/iai.70.2.665-671.2002
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发表时间：
2002-02-01
影响因子：
3.1
通讯作者：
Backert, S
中科院分区：
文献类型：
--
作者：
Selbach, M;Moese, S;Backert, S
幽门螺杆菌（Helicobacter pylori，Hp）cag致病岛（pylori pathogenicity island，派）编码的IV型分泌机制参与了感染过程中的一系列宿主反应。在这里，我们分析了来自cag I和cag 11位点的12个cag派基因的功能，包括完整的virB/D复合物（virB 4、virB 7、virB 8、virB 9、virB 10、virB 11和virD 4）。我们监测了白细胞介素-8（IL-8）分泌、CagA易位和酪氨酸磷酸化，以及在H.幽门螺杆菌感染的AGS胃上皮细胞。对于第一次，我们已经补充了个别cag派基因敲除突变体与其完整的基因表达的穿梭载体，并表明，补充CagA和VirD 4恢复野生型功能。我们的研究结果表明，表型的变化和CagA的磷酸化依赖于所有的virB/D基因和其他几个基因的cag派。IL-8分泌的诱导在很大程度上依赖于同一组基因，但不依赖于CagA和VirD 4。因此，CagA易位和IL-8分泌的诱导分别由VirD 4-CagA依赖性和VirD 4-CagA非依赖性机制调节。VirD 4作为一个可能的衔接蛋白，引导CagA进入IV型分泌通道的功能，在一个模型中。
The type IV secretion machinery encoded by the cag pathogenicity island (PAI) of Helicobacter pylori has been implicated in a series of host responses during infection. Here, we analyzed the function of 12 cag PAI genes from both cag I and cag 11 loci, including the complete virB/D complex (virB4, virB7, virB8, virB9, virB10, virB11, and virD4). We monitored interleukin-8 (IL-8) secretion, CagA translocation and tyrosine phosphorylation, and induction of a scattering ("hummingbird") phenotype upon H. pylori infection of AGS gastric epithelial cells. For the first time, we have complemented individual cag PAI gene knockout mutants with their intact genes expressed from a shuttle vector and showed that complemented CagA and VirD4 restored wild-type function. Our results demonstrate that phenotypic changes and, phosphorylation of CagA depended on all virB/D genes and several other genes of the cag PAI. Induction of IL-8 secretion depended largely on the same set of genes but was independent of CagA and VirD4. Thus, CagA translocation and induction of IL-8 secretion are regulated by VirD4-CagA-dependent and VirD4-CagA-independent mechanisms, respectively. The function of VirD4 as a possible adapter protein which guides CagA into the type IV secretion channel, is presented in a model.