Antibiotic-Dependent Induction of Pseudomonas putida DOT-T1E TtgABC Efflux Pump Is Mediated by the Drug Binding Repressor TtgR
Antibiotic-Dependent Induction of Pseudomonas putida DOT-T1E TtgABC Efflux Pump Is Mediated by the Drug Binding Repressor TtgR
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DOI：
10.1128/aac.47.10.3067-3072.2003
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发表时间：
2003-10
影响因子：
4.9
通讯作者：
Wilson Terán;A. Felipe;A. Segura;Antonia Rojas;J. Ramos;M. Gallegos
中科院分区：
文献类型：
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作者：
Wilson Terán;A. Felipe;A. Segura;Antonia Rojas;J. Ramos;M. Gallegos
恶臭假单胞菌以其代谢能力著称，但近年来已显示出对多种抗生素的耐药性。在恶臭假单胞菌DOT-T1E中，TtgABC外排泵具有广泛的底物专一性，排出抗生素如氨苄西林、甲氧西林、四环素、奈利地酸和氯霉素。我们已经在转录水平上分析了ttgABC外排泵操纵子及其调控基因ttgR在转录水平上对几种结构无关抗生素的响应，并探讨了TtgR蛋白在这一过程中的作用。TtgABC和ttgR在体内以中等基础水平表达，在氯霉素和四环素等疏水抗生素存在时表达增加。体外实验表明，在没有诱导剂的情况下，TtgR与ttgABC和ttgR启动子重叠的回文操作位点结合，并在氯霉素和四环素存在的情况下与之解离。这些结果表明，TtgR阻遏物能够与不同结构的抗生素结合，从而诱导TtgABC多药外排泵对这些抗菌剂的响应。这是第一例耐药结节分裂家族的药物转运蛋白的表达被证明直接受抗生素调节的情况。
ABSTRACT Pseudomonas putida is well known for its metabolic capabilities, but recently, it has been shown to exhibit resistance to a wide range of antibiotics. In P. putida DOT-T1E, the TtgABC efflux pump, which has a broad substrate specificity, extrudes antibiotics such as ampicillin, carbenicillin, tetracycline, nalidixic acid, and chloramphenicol. We have analyzed the expression of the ttgABC efflux pump operon and its regulatory gene, ttgR, in response to several structurally unrelated antibiotics at the transcriptional level and investigated the role of the TtgR protein in this process. ttgABC and ttgR are expressed in vivo at a moderate basal level, which increases in the presence of hydrophobic antibiotics like chloramphenicol and tetracycline. In vitro experiments show that, in the absence of inducers, TtgR binds to a palindromic operator site which overlaps both ttgABC and ttgR promoters and dissociates from it in the presence of chloramphenicol and tetracycline. These results suggest that the TtgR repressor is able to bind to structurally different antibiotics, which allows induction of TtgABC multidrug efflux pump expression in response to these antimicrobial agents. This is the first case in which the expression of a drug transporter of the resistance-nodulation-division family has been shown to be regulated directly by antibiotics.