The Surface Sensor NlpE of Enterohemorrhagic Escherichia coli Contributes to Regulation of the Type III Secretion System and Flagella by the Cpx Response to Adhesion
The Surface Sensor NlpE of Enterohemorrhagic Escherichia coli Contributes to Regulation of the Type III Secretion System and Flagella by the Cpx Response to Adhesion
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DOI：
10.1128/iai.00881-15
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发表时间：
2015-12
影响因子：
3.1
通讯作者：
Takeshi Shimizu;K. Ichimura;M. Noda
中科院分区：
文献类型：
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作者：
Takeshi Shimizu;K. Ichimura;M. Noda
摘要虽然肠出血性大肠杆菌（EHEC）的粘附是感染过程中EHEC与宿主相互作用的核心，但这种粘附如何调节毒力因子仍不清楚。E.大肠杆菌中的Cpx是外膜脂蛋白NlpE依赖的Cpx通路激活因子。因此，我们研究了NlpE在EHEC中对粘附介导的毒力基因表达的作用。肠出血性大肠杆菌中的NlpE有助于上调肠上皮细胞消失（LEE）基因编码的III型分泌系统的位点，并通过激活Cpx途径下调鞭毛蛋白基因的表达，在粘附到疏水性玻璃珠和未分化的Caco-2细胞。此外，EHEC中的LysR同源物A（LrhA）参与调节粘附反应中LEE基因和鞭毛蛋白基因的表达。凝胶迁移率变动分析表明，反应调节因子CpxR与lrhA启动子区结合，通过转录调节因子LrhA调控EHEC中LEE基因和鞭毛蛋白基因的表达。因此，这些结果表明，通过NlpE的粘附信号的传感是重要的III型分泌系统和鞭毛在EHEC感染过程中的表达的调节。
ABSTRACT Although the adhesion of enterohemorrhagic Escherichia coli (EHEC) is central to the EHEC-host interaction during infection, it remains unclear how such adhesion regulates virulence factors. Adhesion to abiotic surfaces by E. coli has been reported to be an outer membrane lipoprotein NlpE-dependent activation cue of the Cpx pathway. Therefore, we investigated the role of NlpE in EHEC on the adhesion-mediated expression of virulence genes. NlpE in EHEC contributed to upregulation of the locus of enterocyte effacement (LEE) genes encoded type III secretion system and to downregulated expression of the flagellin gene by activation of the Cpx pathway during adherence to hydrophobic glass beads and undifferentiated Caco-2 cells. Moreover, LysR homologue A (LrhA) in EHEC was involved in regulating the expression of the LEE genes and flagellin gene in response to adhesion. Gel mobility shift analysis revealed that response regulator CpxR bound to the lrhA promoter region and thereby regulated expressions of the LEE genes and flagellin gene via the transcriptional regulator LrhA in EHEC. Therefore, these results suggest that the sensing of adhesion signals via NlpE is important for regulation of the expression of the type III secretion system and flagella in EHEC during infection.