PrtR Homeostasis Contributes to Pseudomonas aeruginosa Pathogenesis and Resistance against Ciprofloxacin
PrtR Homeostasis Contributes to Pseudomonas aeruginosa Pathogenesis and Resistance against Ciprofloxacin
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DOI：
10.1128/iai.01388-13
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发表时间：
2014-02
影响因子：
3.1
通讯作者：
Ziyu Sun;Jing Shi;Chang Liu;Yongxin Jin;Kewei Li;Ronghao Chen;Shouguang Jin;Weihui Wu
中科院分区：
文献类型：
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作者：
Ziyu Sun;Jing Shi;Chang Liu;Yongxin Jin;Kewei Li;Ronghao Chen;Shouguang Jin;Weihui Wu
摘要 铜绿假单胞菌是一种机会致病菌，可引起人类急性和慢性感染。脓毒素是由铜绿假单胞菌产生的细菌素，通常通过生产菌株裂解释放。 pyocin 基因的表达受到 PrtR 的负向调节，PrtR 在 SOS 反应下被裂解，导致 pyocin 合成基因的上调。之前，我们证明了PrtR是III型分泌系统（T3SS）表达所必需的，而T3SS是铜绿假单胞菌的重要毒力成分。在这项研究中，我们证明 prtR 突变会导致小鼠急性肺炎模型中细菌定植减少。对受感染小鼠的支气管肺泡灌洗液中的细菌和宿主细胞的检查表明，PrtR 的表达是由中性粒细胞释放的活性氧 (ROS) 诱导的。我们进一步证明，已知可诱导 SOS 反应和脓毒菌素产生的过氧化氢或环丙沙星治疗会导致 PrtR mRNA 水平升高。 tac 启动子过度表达 PrtR 会抑制内源性 prtR 启动子活性，电泳迁移率变动分析显示 PrtR 与其自身的启动子结合，表明存在自抑制调节机制。质粒表达的高水平 PrtR 导致感染期间 T3SS 基因表达增加，并对环丙沙星产生更高的耐药性。总体而言，我们的结果表明，PrtR 的自身抑制有助于维持 PrtR 的相对稳定水平，在 ROS 存在的情况下允许 T3SS 基因表达，同时通过限制化脓菌素的产生来增加细菌对应激（如环丙沙星）的耐受性。
ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that causes acute and chronic infections in humans. Pyocins are bacteriocins produced by P. aeruginosa that are usually released through lysis of the producer strains. Expression of pyocin genes is negatively regulated by PrtR, which gets cleaved under SOS response, leading to upregulation of pyocin synthetic genes. Previously, we demonstrated that PrtR is required for the expression of type III secretion system (T3SS), which is an important virulence component of P. aeruginosa. In this study, we demonstrate that mutation in prtR results in reduced bacterial colonization in a mouse acute pneumonia model. Examination of bacterial and host cells in the bronchoalveolar lavage fluids from infected mice revealed that expression of PrtR is induced by reactive oxygen species (ROS) released by neutrophils. We further demonstrate that treatment with hydrogen peroxide or ciprofloxacin, known to induce the SOS response and pyocin production, resulted in an elevated PrtR mRNA level. Overexpression of PrtR by a tac promoter repressed the endogenous prtR promoter activity, and electrophoretic mobility shift assay revealed that PrtR binds to its own promoter, suggesting an autorepressive mechanism of regulation. A high level of PrtR expressed from a plasmid resulted in increased T3SS gene expression during infection and higher resistance against ciprofloxacin. Overall, our results suggest that the autorepression of PrtR contributes to the maintenance of a relatively stable level of PrtR, which is permissive to T3SS gene expression in the presence of ROS while increasing bacterial tolerance to stresses, such as ciprofloxacin, by limiting pyocin production.