铜绿假单胞菌中III型分泌系统受Rhl和PQS群体感应系统调节

摘要：【目的】研究铜绿假单胞菌中群体感应系统（Quorum sensing, QS）与III型分泌系统（Type III secretion system, T3SS）的关系。【方法】通过基因敲除的方法破坏铜绿假单胞菌QS系统相关基因，将T3SS相关基因exoS、exoY、exoT、exsD-pscA-L启动子-报道子luxCDABE融合体整合到野生型菌株及QS系统突变菌株的染色体组上，通过检测启动子活性，比较这些基因在不同菌株中的表达情况。【结果】研究结果表明，T3SS中的exoS与exoT在pqsR基因突变体中的表达有明显的增强，Rhl系统对这四种基因的表达具有抑制作用，而Las系统存在与否对T3SS基本没有影响。【结论】铜绿假单胞菌中的Rhl系统和奎诺酮信号（Pseudomonas Quinolone Signal, PQS）系统对T3SS相关基因的表达具有重要的调节作用。

Regulation of type III secretion system by Rhl and PQS quorum sensing systems in Pseudomonas aeruginosa

Abstract: Objective] To investigate the relationship between quorum sensing (QS) and type III secretion system (T3SS) in Pseudomonas aeruginosa. Methods] We constructed several gene knockout mutants of QS systems. The promoters of the T3SS genes, exoS , exoY, exoT and exsD-pscA-L were cloned and fused upstream of the luminescence reporter gene cluster, luxCDABE. The reporter constructs were integrated on the chromosome in the wild type strain PAO1 and the QS mutants respectively, and the expression of the T3SS genes in these strains was compared. Results] The expression of exoS and exoT in pqsR mutant was increased significantly. The Rhl system repressed the activities of the four T3SS genes and the Las system had no effect. Conclusion] The results indicate that the Rhl and Pseudomonas Quinolone Signal (PQS) systems play an important role in regulating T3SS gene expression in Pseudomonas aeruginosa.