Lee Li-Fong, Huang Yi-Jiun, Chen Carton W
Institute of Genetics, National Yang-Ming University, Shih-Pai, Taipei 112, Taiwan.
Arch Microbiol. 2003 Sep;180(3):176-84. doi: 10.1007/s00203-003-0574-z. Epub 2003 Jul 9.
Multidrug resistance (MDR) systems are ubiquitously present in prokaryotes and eukaryotes and defend both types of organisms against toxic compounds in the environment. Four families of MDR systems have been described, each family removing a broad spectrum of compounds by a specific membrane-bound active efflux pump. In the present study, at least four MDR systems were identified genetically in the soil bacterium Streptomyces lividans. The resistance genes of three of these systems were cloned and sequenced. Two of them are accompanied by a repressor gene. These MDR gene sequences are found in most other Streptomyces species investigated. Unlike the constitutively expressed MDR genes in Escherichia coli and other gram-negative bacteria, all of the Streptomyces genes were repressed under laboratory conditions, and resistance arose by mutations in the repressor genes.
多药耐药（MDR）系统普遍存在于原核生物和真核生物中，保护这两类生物体免受环境中有毒化合物的侵害。已描述了四类MDR系统，每个家族通过特定的膜结合活性外排泵去除广谱化合物。在本研究中，在土壤细菌天蓝色链霉菌中通过基因鉴定出至少四种MDR系统。其中三个系统的抗性基因被克隆并测序。其中两个伴随着一个阻遏基因。这些MDR基因序列在大多数其他被研究的链霉菌物种中都能找到。与大肠杆菌和其他革兰氏阴性细菌中组成型表达的MDR基因不同，所有链霉菌基因在实验室条件下均被抑制，并且抗性是由阻遏基因突变产生的。
