Miklavič Špela, Kogovšek Polona, Hodnik Vesna, Korošec Jernej, Kladnik Aleš, Anderluh Gregor, Gutierrez-Aguirre Ion, Maček Peter, Butala Matej
Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
Department of Biotechnology and Systems Biology, National Institute of Biology, 1000 Ljubljana, Slovenia.
FEMS Microbiol Lett. 2015 May;362(10). doi: 10.1093/femsle/fnv069. Epub 2015 Apr 28.
The opportunistic pathogen Pseudomonas aeruginosa uses quorum-sensing systems to regulate collective behaviour in response to the environment, by linking the expression of particular genes to population density. The quorum-sensing transcription factors LasR and RhlR and their cognate N-acyl-homoserine lactone (HSL) signals N-3-oxo-dodecanoyl-L-HSL (3OC12-HSL) and N-butanoyl-L-HSL (C4-HSL) control the expression of several hundred genes, which include those involved in virulence and biofilm formation. Here, we have focused on regulation of the expression of the putative virulence factor gene, rahU. We show that the intact las-rhl box immediately upstream of the -35 promoter element is needed for rahU expression in P. aeruginosa. Using β-galactosidase assays and quantification of the mRNA levels for rahU, lasR and rhlR, we provide evidence that for rahU promoter activity, 3OC12-HSL-LasR is not sufficient, and instead C4-HSL-RhlR is the trigger. Furthermore, surface plasmon resonance analysis revealed that RahU binds the biosurfactant rhamnolipids. Thus, this is the first report of a bacterial molecule that interacts with RahU.
机会致病菌铜绿假单胞菌利用群体感应系统，通过将特定基因的表达与种群密度联系起来，来调节其对环境的集体行为。群体感应转录因子LasR和RhlR以及它们对应的N-酰基高丝氨酸内酯（HSL）信号N-3-氧代十二烷酰-L-高丝氨酸内酯（3OC12-HSL）和N-丁酰-L-高丝氨酸内酯（C4-HSL）控制着数百个基因的表达，这些基因包括那些参与毒力和生物膜形成的基因。在这里，我们重点研究了假定的毒力因子基因rahU的表达调控。我们发现，在铜绿假单胞菌中，rahU表达需要位于-35启动子元件上游的完整las-rhl框。通过β-半乳糖苷酶分析以及对rahU、lasR和rhlR的mRNA水平进行定量，我们提供了证据表明，对于rahU启动子活性，3OC12-HSL-LasR并不足够，相反，C4-HSL-RhlR才是触发因素。此外，表面等离子体共振分析表明，RahU与生物表面活性剂鼠李糖脂结合。因此，这是关于一种与RahU相互作用的细菌分子的首次报道。
