N-Acylhomoserine lactones involved in quorum sensing control the type VI secretion system, biofilm formation, protease production, and in vivo virulence in a clinical isolate of Aeromonas hydrophila
N-Acylhomoserine lactones involved in quorum sensing control the type VI secretion system, biofilm formation, protease production, and in vivo virulence in a clinical isolate of Aeromonas hydrophila
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DOI：
10.1099/mic.0.031575-0
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发表时间：
2009-11-01
期刊：
影响因子：
2.8
通讯作者：
Chopra, Ashok K.
中科院分区：
文献类型：
--
作者：
Khajanchi, Bijay K.;Sha, Jian;Chopra, Ashok K.
在这项研究中，我们通过产生一个双基因敲除的Delta ahyRI突变体，研究了N-酰基高丝氨酸内酯(AHLS)(AHLS)介导的群体感应(QS)在嗜水气单胞菌腹泻分离株SSU毒力中的作用。与野生型(WT)菌株相比，Delta ahyRI突变株的蛋白水解酶产量显著降低。重要的是，根据Western印迹分析，Delta ahyR1突变体不能分泌与VI型分泌系统(T6SS)相关的效应物，即溶血素共调节蛋白和Valine-甘氨酸重复蛋白家族，而在WT A.嗜水菌的培养上清液中检测到显著水平的这些效应物。相反，当ahyRI基因缺失时，人结肠上皮细胞中III型分泌系统(T3SS)效应物AexU的产生和易位没有受到影响。结晶紫染色试验表明，与WT株相比，Delta ahyRI突变体的固体表面相关生物膜的形成显著减少。扫描电子显微镜观察表明，与WT菌株相比，Delta ahyRI突变体在形成结构生物膜方面也存在缺陷，因为它的丝状结构较少，表面产生了明显的胞外多糖。AhyRI的这些作用可以通过在反式表达ahyRI基因或在Delta ahyRI/ahyR(+)互补菌株中外源添加AHLS来补充。在小鼠致死性实验中，当我们从亲本菌株中删除ahyRI基因时，观察到50%的衰减。综上所述，我们的数据表明，AHL介导的OS通过调节T6SS、金属蛋白酶、产物和生物膜的形成来调节嗜水气单胞菌的毒力。
In this study, we delineated the role of N-acylhomoserine lactone(s) (AHLs)-mediated quorum sensing (QS) in the virulence of diarrhoeal isolate SSU of Aeromonas hydrophila by generating a double knockout Delta ahyRI mutant. Protease production was substantially reduced in the Delta ahyRI mutant when compared with that in the wild-type (WT) strain. Importantly, based on Western blot analysis, the Delta ahyR1 mutant was unable to secrete type VI secretion system (T6SS)-associated effectors, namely haemolysin coregulated protein and the valine-glycine repeat family of proteins, while significant levels of these effectors were detected in the culture supernatant of the WT A. hydrophila. In contrast, the production and translocation of the type III secretion system (T3SS) effector AexU in human colonic epithelial cells were not affected when the ahyRI genes were deleted. Solid surface-associated biofilm formation was significantly reduced in the Delta ahyRI mutant when compared with that in the WT strain, as determined by a crystal violet staining assay. Scanning electron microscopic observations revealed that the Delta ahyRI mutant was also defective in the formation of structured biofilm, as it was less filamentous and produced a distinct exopolysaccharide on its surface when compared with the structured biofilm produced by the WT strain. These effects of AhyRI could be complemented either by expressing the ahyRI genes in trans or by the exogeneous addition of AHLs to the Delta ahyRI/ahyR(+) complemented strain. In a mouse lethality experiment, 50% attenuation was observed when we deleted the ahyRI genes from the parental strain of A. hydrophila. Together, our data suggest that AHL-mediated OS modulates the virulence of A. hydrophila SSU by regulating the T6SS, metalloprotease, production and biofilm formation.