摘要

基于生物膜的细菌感染非常难以根除，因为细菌在生物膜群落中表现出高度的抗生素顽固性。在机会性病原体铜绿假单胞菌中，生物膜顽固性是多因素的，并且部分源于生物膜中抗性基因的优先表达，与指数相浮游细胞相比。一种这样的机制涉及ndvB，我们之前已经证明这是在生物膜中特异性表达的。在这项研究中，我们通过开发不稳定的GFP转录记者来观察ndvB的表达模式，调查了这种生活方式特异性表达的调控基础。我们发现，除了在生物膜中的表达之外，ndvB在浮游细胞中也进入稳定期。 ndvB在两个生长阶段中的转录均显示依赖于稳定期西格玛因子RpoS，并且ndvB启动子中推定的RpoS结合位点的突变废除了稳定期细胞中启动子的活性。总体而言，我们扩大了对铜绿假单胞菌中ndvB时间表达的理解，并揭示了其生长相依赖性表达的调控基础。

Chronic, biofilm-based bacterial infections are exceptionally difficult to eradicate due to the high degree of antibiotic recalcitrance exhibited by cells in biofilm communities. In the opportunistic pathogen Pseudomonas aeruginosa, biofilm recalcitrance is multifactorial and arises in part from the preferential expression of resistance genes in biofilms compared to exponential phase planktonic cells. One such mechanism involves ndvB, which we have previously shown to be expressed specifically in biofilms. In this study, we investigated the regulatory basis of this lifestyle-specific expression by developing an unstable GFP transcriptional reporter to observe the expression pattern of ndvB. We found that, in addition to its expression in biofilms, ndvB was also upregulated in planktonic cells as they enter stationary phase. The transcription of ndvB in both growth phases was shown to be dependent on the stationary phase sigma factor RpoS, and mutation of a putative RpoS binding site in the ndvB promoter abolished the activity of the promoter in stationary phase cells. Overall, we have expanded our understanding of the temporal expression of ndvB in P. aeruginosa and have uncovered a regulatory basis for its growth phase-dependent expression.

http://aem.asm.org/content/early/2018/01/15/AEM.02762-17.abstract