Zhang Chuan-Zhen, Chen Pin-Xian, Yang Lei, Li Wan, Chang Man-Xia, Jiang Hong-Xia
Microb Drug Resist. 2018 Mar;24(2):120-125. doi: 10.1089/mdr.2017.0086. Epub 2017 Jun 26.
The aim of this study was to determine the expression of eight other functional transporter genes upon acrAB inactivation and also the expression of acrAB when the function of eight other transporters are impaired in Salmonella enterica. We used single- or multigene deletion mutants (i.e., ΔacrA, ΔacrB, ΔtolC, ΔacrAB, ΔacrEF, ΔacrD, ΔmdsABC, ΔmdtABC, ΔemrAB, ΔmacAB, ΔmdfA, ΔmdtK, ΔacrABramA, ΔacrABmarA, and ΔacrABsoxS) and real time (RT)-PCR to quantify the expression of different pump and regulator genes; infection ability was characterized by adhesion and invasion assays. The expression of acrAB operon was increased upon acrB inactivation. Single deletion of acrA or tolC also increased expression of acrB. The deletion of acrAB increased expression of eight other functional efflux pumps genes and vice versa, in which increased expression of ramA and marA was also detected. Mutants containing single deletions of functional pump genes were attenuated in cells. In conclusion, there is a feedback mechanism that coordinates regulation of AcrAB-TolC and eight other functional efflux pumps through the global transcriptional regulators ramA and marA in S. enterica serovar Typhimurium.
本研究的目的是确定在鼠伤寒沙门氏菌中acrAB失活时其他八个功能性转运蛋白基因的表达情况，以及其他八个转运蛋白功能受损时acrAB的表达情况。我们使用单基因或多基因缺失突变体（即ΔacrA、ΔacrB、ΔtolC、ΔacrAB、ΔacrEF、ΔacrD、ΔmdsABC、ΔmdtABC、ΔemrAB、ΔmacAB、ΔmdfA、ΔmdtK、ΔacrABramA、ΔacrABmarA和ΔacrABsoxS）以及实时（RT）-PCR来定量不同泵和调节基因的表达；通过黏附试验和侵袭试验来表征感染能力。acrB失活后acrAB操纵子的表达增加。单独缺失acrA或tolC也会增加acrB的表达。缺失acrAB会增加其他八个功能性外排泵基因的表达，反之亦然，其中还检测到ramA和marA的表达增加。含有功能性泵基因单缺失的突变体在细胞中减毒。总之，在鼠伤寒沙门氏菌中存在一种反馈机制，通过全局转录调节因子ramA和marA来协调AcrAB-TolC和其他八个功能性外排泵的调节。
