Intra-leukocyte expression of two-component systems in Ehrlichia chaffeensis and Anaplasma phagocytophilum and effects of the histidine kinase inhibitor closantel
Intra-leukocyte expression of two-component systems in Ehrlichia chaffeensis and Anaplasma phagocytophilum and effects of the histidine kinase inhibitor closantel
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DOI：
10.1111/j.1462-5822.2006.00704.x
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发表时间：
2006-08-01
影响因子：
3.4
通讯作者：
Rikihisa, Yasuko
中科院分区：
文献类型：
--
作者：
Cheng, Zhihui;Kumagai, Yumi;Rikihisa, Yasuko
双组分系统（TCS）由一对传感器组氨酸激酶和一个反应调节剂组成，允许细菌通过特定的基因激活或抑制来感知信号并对其环境的变化做出反应。本研究探讨TCS专性细胞内细菌查菲埃里希体和嗜吞噬细胞无形体，导致人类单核细胞埃里希体病（HME）和人类粒细胞无形体病（HGA）分别。E. chaffeensis和A.预测嗜吞噬细胞菌各自编码三对TCS。所有六个基因编码的三个组氨酸激酶和三个反应调节因子在两个E。chaffeensis和A.在人白细胞中培养的嗜吞噬细胞菌宿主无细胞E. chaffeensis或A.用组氨酸激酶抑制剂Closantel完全阻断了嗜吞噬细胞菌对宿主细胞的感染。感染后1天用氯氰碘柳胺处理感染细胞以剂量依赖性方式清除感染。E.克隆了Chaffeensis，表达了重组蛋白，并制备了多克隆抗体。免疫荧光双标记和Western blot分析表明，所有六个蛋白在细胞培养中表达。对三种重组大肠杆菌组氨酸激酶的自激酶活性进行了测定。Closantel对Chaffeensis的生长有抑制作用。一些E. chaffeensis基因，包括6个TCS基因，在氯氰碘柳胺处理后5-60分钟内下调。这些结果表明，这些TCS在E. chaffeensis和A.人白细胞中的嗜吞噬细胞菌。
The two-component system (TCS) composed of a pair of a sensor histidine kinase and a response regulator, allows bacteria to sense signals and respond to changes in their environment through specific gene activation or repression. The present study examined TCS in the obligatory intracellular bacteria Ehrlichia chaffeensis and Anaplasma phagocytophilum, that cause human monocytic ehrlichiosis (HME) and human granulocytic anaplasmosis (HGA) respectively. The genomes of E. chaffeensis and A. phagocytophilum were each predicted to encode three pairs of TCSs. All six genes encoding three histidine kinases and three response regulators were expressed in both E. chaffeensis and A. phagocytophilum cultured in human leukocytes. Pretreatment of host cell-free E. chaffeensis or A. phagocytophilum with closantel, an inhibitor of histidine kinases, completely blocked the infection of host cells. Treatment of infected cells 1 day post infection with closantel cleared infection in dose-dependent manner. All six genes in E. chaffeensis were cloned, recombinant proteins were expressed, and polyclonal antibodies were produced. Double immunofluorescence labelling and Western blot analysis revealed that all six proteins were expressed in cell culture. Autokinase activities of the three recombinant histidine kinases from E. chaffeensis were inhibited by closantel in vitro. A number of E. chaffeensis genes, including the six TCS genes, were downregulated within 5-60 min post closantel treatment. These results suggest that these TCSs play an essential role in infection and survival of E. chaffeensis and A. phagocytophilum in human leukocytes.