Two-component systems (TCSs) are widespread regulatory systems which can help bacteria to control their cellular functions and respond to a diverse range of stimuli. The KdpD/KdpE system had been well studied for regulating potassium transport and identified as an adaptive regulator involved in the virulence of some pathogenic bacteria, but its role in avian pathogenic Escherichia coli (APEC) was still unknown. In this study, the mutant strain AE17ΔKdpDE was obtained successfully of a clinical APEC isolation AE17 using the lambda Red recombinase system and performed the transcriptional sequencing of the wild type strain AE17 and the mutant strain AE17ΔKdpDE. The transcriptional sequencing results revealed that the KdpD/KdpE two-component system mainly influenced the expression of the genes covering metabolic pathways, flagellar assembly, global transcription regulator. The expression of some flagellar-related genes detecting by quantitative real-time PCR was consistent with the results of transcriptional sequencing. Importantly, fewer flagellum of the mutant strain AE17ΔKdpDE was observed than AE17 using the transmission electron microscope and a decreased motility circle of AE17ΔKdpDE appeared in the semisolid medium. In addition, the serum bactericidal assay was carried out with the specific-pathogen-free chicken in different dilution and the survival ability in the serum of AE17ΔKdpDE was also obviously lower than that of AE17. These results suggested that in APEC, the KdpD/KdpE two-component system mainly influenced the expression of flagella-related genes, the flagellum formation, the motility and antiserum bactericidal activity.

中文翻译：

---

KdpD / KdpE两组分系统有助于禽类致病性大肠杆菌的活力和致病性。

两组分系统（TCS）是广泛使用的调节系统，可以帮助细菌控制其细胞功能并对各种刺激作出反应。KdpD / KdpE系统已被广泛研究以调节钾的运输，并被确定为参与某些病原细菌毒力的适应性调节剂，但其在禽病原性大肠杆菌（APEC）中的作用仍然未知。在这项研究中，使用λRed重组酶系统成功地从临床APEC分离AE17中获得了突变株AE17ΔKdpDE，并对野生型株AE17和突变株AE17ΔKdpDE进行了转录测序。转录测序结果表明，KdpD / KdpE两组分系统主要影响代谢途径，鞭毛组装，全球转录调节剂。定量实时荧光定量PCR检测到的一些鞭毛相关基因的表达与转录测序的结果一致。重要的是，使用透射电子显微镜观察到的突变菌株AE17ΔKdpDE的鞭毛少于AE17，并且在半固体培养基中出现了AE17ΔKdpDE的运动圆降低。另外，用不同稀释度的无特异性病原体鸡进行血清杀菌试验，AE17ΔKdpDE在血清中的生存能力也明显低于AE17。这些结果表明，在APEC中，KdpD / KdpE两组分系统主要影响鞭毛相关基因的表达，鞭毛的形成，运动性和抗血清杀菌活性。定量实时荧光定量PCR检测到的一些鞭毛相关基因的表达与转录测序的结果一致。重要的是，使用透射电子显微镜观察到的突变菌株AE17ΔKdpDE的鞭毛少于AE17，并且在半固体培养基中出现了AE17ΔKdpDE的运动圆降低。另外，用不同稀释度的无特异性病原体鸡进行血清杀菌试验，AE17ΔKdpDE在血清中的生存能力也明显低于AE17。这些结果表明，在APEC中，KdpD / KdpE两组分系统主要影响鞭毛相关基因的表达，鞭毛的形成，运动性和抗血清杀菌活性。定量实时PCR检测到的一些鞭毛相关基因的表达与转录测序的结果一致。重要的是，使用透射电子显微镜观察到的突变菌株AE17ΔKdpDE的鞭毛少于AE17，并且在半固体培养基中出现了AE17ΔKdpDE的运动圆降低。另外，用不同稀释度的无特异性病原体鸡进行血清杀菌试验，AE17ΔKdpDE在血清中的生存能力也明显低于AE17。这些结果表明，在APEC中，KdpD / KdpE两组分系统主要影响鞭毛相关基因的表达，鞭毛的形成，运动性和抗血清杀菌活性。