摘要

由于生物膜群落中的细胞表现出高度的抗药性，因此很难根除基于生物膜的慢性细菌感染。在机会性病原体铜绿假单胞菌中，生物膜顽固是多因素的，部分原因是与指数期浮游细胞相比，生物膜中抗性基因的优先表达。其中一种机制涉及ndvB，我们先前已证明它在生物膜中特异性表达。在这项研究中，我们通过开发不稳定的绿色荧光蛋白（GFP）转录报告基因来观察ndvB的表达模式，研究了这种生活方式特异性表达的调控基础。我们发现，除了其在生物膜中的表达外，ndvB在进入稳定期的浮游细胞中也被上调。已显示ndvB在两个生长期的转录均依赖于固定相sigma因子RpoS，并且ndvB启动子中假定的RpoS结合位点的突变消除了该启动子在固定相细胞中的活性。总体而言，我们扩展了对绿脓杆菌中ndvB瞬时表达的理解，并发现了其生长阶段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 green fluorescent protein (GFP) transcriptional reporter to observe the expression pattern of ndvB. We found that in addition to its expression in biofilms, ndvB was 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.

https://aem.asm.org/content/84/7/e02762-17.short