van Veen H W, Callaghan R, Soceneantu L, Sardini A, Konings W N, Higgins C F
Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
Nature. 1998 Jan 15;391(6664):291-5. doi: 10.1038/34669.
Bacteria have developed many fascinating antibiotic-resistance mechanisms. A protein in Lactococcus lactis, LmrA, mediates antibiotic resistance by extruding amphiphilic compounds from the inner leaflet of the cytoplasmic membrane. Unlike other known bacterial multidrug-resistance proteins, LmrA is an ATP-binding cassette (ABC) transporter. The human multidrug-resistance P-glycoprotein, encoded by the MDR1 gene, is also an ABC transporter, overexpression of which is one of the principal causes of resistance of human cancers to chemotherapy. We expressed lmrA in human lung fibroblast cells. Surprisingly, LmrA was targeted to the plasma membrane and conferred typical multidrug resistance on these human cells. The pharmacological characteristics of LmrA and P-glycoprotein-expressing lung fibroblasts were very similar, and the affinities of both proteins for vinblastine and magnesium-ATP were indistinguishable. Blockers of P-glycoprotein-mediated multidrug resistance also inhibited LmrA-dependent drug resistance. Kinetic analysis of drug dissociation from LmrA expressed in plasma membranes of insect cells revealed the presence of two allosterically linked drug-binding sites indistinguishable from those of P-glycoprotein. These findings have implications for the reversal of antibiotic resistance in pathogenic microorganisms. Taken together, they demonstrate that bacterial LmrA and human P-glycoprotein are functionally interchangeable and that this type of multidrug-resistance efflux pump is conserved from bacteria to man.
细菌已经形成了许多迷人的抗生素耐药机制。乳酸乳球菌中的一种蛋白质LmrA通过从细胞质膜内小叶挤出两亲性化合物来介导抗生素耐药性。与其他已知的细菌多药耐药蛋白不同，LmrA是一种ATP结合盒（ABC）转运蛋白。由MDR1基因编码的人类多药耐药P-糖蛋白也是一种ABC转运蛋白，其过表达是人类癌症对化疗耐药的主要原因之一。我们在人肺成纤维细胞中表达了lmrA。令人惊讶的是，LmrA定位于质膜，并赋予这些人类细胞典型的多药耐药性。表达LmrA和P-糖蛋白的肺成纤维细胞的药理学特性非常相似，并且这两种蛋白对长春碱和镁-ATP的亲和力无法区分。P-糖蛋白介导的多药耐药性的阻滞剂也抑制LmrA依赖性耐药性。对昆虫细胞质膜中表达的LmrA的药物解离动力学分析表明，存在两个与P-糖蛋白无法区分的变构连接药物结合位点。这些发现对致病微生物抗生素耐药性的逆转具有启示意义。综上所述，它们表明细菌LmrA和人类P-糖蛋白在功能上是可互换的，并且这种类型的多药耐药性外排泵从细菌到人类都是保守的。
