PDF(Pubmed)
Abstract：
The transcription factor PsrA regulates fatty acid metabolism, the type III secretion system, and quinolone signaling quorum sensing system in Pseudomonas aeruginosa. To explore additional roles of PsrA in P. aeruginosa, this study engineered a P. aeruginosa PAO1 strain to carry a recombinant plasmid with the psrA gene (pMMBpsrA) and examined the impact of elevated psrA expression to the bacterium. Transcriptomic analysis revealed that PsrA significantly downregulated genes encoding the master quorum-sensing regulators, RhlR and LasR, and influenced many quorum-sensing-associated genes. The role of PsrA in quorum sensing was further corroborated by testing autoinducer synthesis in PAO1 [pMMBpsrA] using two reporter bacteria strains Chromobacterium violaceum CV026 and Escherichia coli [pSB1075], which respond to short- and long-chain acyl homoserine lactones, respectively. Phenotypic comparisons of isogenic ΔpsrA, ΔlasR, and ΔpsrAΔlasR mutants revealed that the reduced elastase, caseinase, and swarming activity in PAO1 [pMMBpsrA] were likely mediated through LasR. Additionally, electrophoretic mobility shift assays demonstrated that recombinant PsrA could bind to the lasR promoter at a 5\'-AAACGTTTGCTT-3\' sequence, which displays moderate similarity to the previously reported consensus PsrA binding motif. Furthermore, the PsrA effector molecule oleic acid inhibited PsrA binding to the lasR promoter and restored several quorum sensing-related phenotypes to wild-type levels. These findings suggest that PsrA regulates certain quorum-sensing phenotypes by negatively regulating lasR expression, with oleic acid acting as a crucial signaling molecule.
摘要：
转录因子PsrA调节脂肪酸代谢，III型分泌系统，铜绿假单胞菌的喹诺酮信号传导群体感应系统。探讨PsrA在铜绿假单胞菌中的其他作用，这项研究改造了铜绿假单胞菌PAO1菌株，使其携带具有psrA基因（pMMBpsrA）的重组质粒，并检查了psrA表达升高对细菌的影响。转录组分析显示，PsrA显着下调编码主群体感应调节因子的基因，RhlR和LasR,并影响了许多群体感应相关基因。PsrA在群体感应中的作用通过使用两种报告细菌菌株绿色细菌CV026和大肠杆菌[pSB1075]测试PAO1[pMMBpsrA]中的自诱导合成来进一步证实，响应短链和长链酰基高丝氨酸内酯，分别。等基因ΔpsrA的表型比较，ΔlasR,和ΔpsrAΔlasR突变体揭示了减少的弹性蛋白酶，酪蛋白蛋白酶,PAO1[pMMBpsrA]中的成群活动可能是通过LasR介导的。此外,电泳迁移率转移试验表明，重组PsrA可以在5'-AAACGTTGCTT-3'序列上与lasR启动子结合，与先前报道的共有PsrA结合基序显示中等相似性。此外，PsrA效应分子油酸抑制了PsrA与lasR启动子的结合，并将几种群体感应相关的表型恢复到野生型水平。这些发现表明，PsrA通过负调节lasR表达来调节某些群体感应表型，油酸作为一个重要的信号分子。
