Daury Laetitia, Orange François, Taveau Jean-Christophe, Verchère Alice, Monlezun Laura, Gounou Céline, Marreddy Ravi K R, Picard Martin, Broutin Isabelle, Pos Klaas M, Lambert Olivier
Université de Bordeaux, CBMN UMR 5248, Bordeaux INP, IECB, Pessac F-33600, France.
CNRS, CBMN UMR 5248, Pessac F-33600, France.
Nat Commun. 2016 Feb 12;7:10731. doi: 10.1038/ncomms10731.
Tripartite multidrug efflux systems of Gram-negative bacteria are composed of an inner membrane transporter, an outer membrane channel and a periplasmic adaptor protein. They are assumed to form ducts inside the periplasm facilitating drug exit across the outer membrane. Here we present the reconstitution of native Pseudomonas aeruginosa MexAB-OprM and Escherichia coli AcrAB-TolC tripartite Resistance Nodulation and cell Division (RND) efflux systems in a lipid nanodisc system. Single-particle analysis by electron microscopy reveals the inner and outer membrane protein components linked together via the periplasmic adaptor protein. This intrinsic ability of the native components to self-assemble also leads to the formation of a stable interspecies AcrA-MexB-TolC complex suggesting a common mechanism of tripartite assembly. Projection structures of all three complexes emphasize the role of the periplasmic adaptor protein as part of the exit duct with no physical interaction between the inner and outer membrane components.
革兰氏阴性菌的三方多药外排系统由内膜转运蛋白、外膜通道和周质适配蛋白组成。它们被认为在周质内形成管道，促进药物穿过外膜排出。在此，我们展示了在脂质纳米盘系统中对天然铜绿假单胞菌MexAB - OprM和大肠杆菌AcrAB - TolC三方耐药结瘤和细胞分裂（RND）外排系统的重构。通过电子显微镜进行的单颗粒分析揭示了内膜和外膜蛋白组分通过周质适配蛋白连接在一起。天然组分的这种自组装内在能力还导致形成稳定的种间AcrA - MexB - TolC复合物，表明三方组装存在共同机制。所有三种复合物的投影结构强调了周质适配蛋白作为排出管道一部分的作用，内膜和外膜组分之间没有物理相互作用。
