The ABC of Biofilm Drug Tolerance: the MerR-Like Regulator BrlR Is an Activator of ABC Transport Systems, with PA1874-77 Contributing to the Tolerance of Pseudomonas aeruginosa Biofilms to Tobramycin
The ABC of Biofilm Drug Tolerance: the MerR-Like Regulator BrlR Is an Activator of ABC Transport Systems, with PA1874-77 Contributing to the Tolerance of Pseudomonas aeruginosa Biofilms to Tobramycin
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DOI：
10.1128/aac.01981-17
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发表时间：
2018-02-01
影响因子：
4.9
通讯作者：
Sauer, Karin
中科院分区：
文献类型：
--
作者：
Poudyal, Bandita;Sauer, Karin
生物膜的一个标志是它们对抗菌剂杀灭的耐受性。在铜绿假单胞菌中，生物膜药物耐受性需要c-di-GMP响应性MerR转录调节因子BrlR。然而，BrlR介导生物膜药物耐受性的机制尚未阐明。在这里，我们证明，BrlR激活至少7个ABC运输系统，包括PA 1874-PA 1875-PA 1876-PA 1877（PA 1874 -77）操纵子的表达，染色质免疫沉淀和DNA结合试验证实BrlR结合到PA 1874 -77的启动子区域。7个ABC转运系统的插入失活使铜绿假单胞菌PAO 1生物膜对妥布霉素或诺氟沙星敏感。敏感性与药物蓄积有关，BrlR以依赖于多药外排泵和PA 1874 -77 ABC转运系统的方式促进诺氟沙星蓄积。此外，相应ABC转运系统的失活消除了生物膜对妥布霉素而不是诺氟沙星的杀伤的抑制，表明药物积累与生物膜药物耐受性无关。我们的研究结果首次表明，BrlR，MerR型转录激活因子，激活基因编码的几个ABC运输系统，除了多个多药外排泵基因。此外，我们的数据证实了BrlR靶点有助于药物耐受性，可能与生物膜耐受性由多种因素引起的流行教条相反。
A hallmark of biofilms is their tolerance to killing by antimicrobial agents. In Pseudomonas aeruginosa, biofilm drug tolerance requires the c-di-GMP-responsive MerR transcriptional regulator BrlR. However, the mechanism by which BrlR mediates biofilm drug tolerance has not been elucidated. Here, we demonstrate that BrlR activates the expression of at least 7 ABC transport systems, including the PA1874-PA1875PA1876- PA1877 (PA1874-77) operon, with chromatin immunoprecipitation and DNA binding assays confirming BrlR binding to the promoter region of PA1874-77. Insertional inactivation of the 7 ABC transport systems rendered P. aeruginosa PAO1 biofilms susceptible to tobramycin or norfloxacin. Susceptibility was linked to drug accumulation, with BrlR contributing to norfloxacin accumulation in a manner dependent on multidrug efflux pumps and the PA1874-77 ABC transport system. Inactivation of the respective ABC transport system, furthermore, eliminated the recalcitrance of biofilms to killing by tobramycin but not norfloxacin, indicating that drug accumulation is not linked to biofilm drug tolerance. Our findings indicate for the first time that BrlR, a MerR-type transcriptional activator, activates genes encoding several ABC transport systems, in addition to multiple multidrug efflux pump genes. Moreover, our data confirm a BrlR target contributing to drug tolerance, likely countering the prevailing dogma that biofilm tolerance arises from a multiplicity of factors.