Krishnamoorthy Ganesh, Wolloscheck David, Weeks Jon W, Croft Cameron, Rybenkov Valentin V, Zgurskaya Helen I
University of Oklahoma, Department of Chemistry and Biochemistry, Norman, Oklahoma, USA.
University of Oklahoma, Department of Chemistry and Biochemistry, Norman, Oklahoma, USA
Antimicrob Agents Chemother. 2016 Nov 21;60(12):7372-7381. doi: 10.1128/AAC.01882-16. Print 2016 Dec.
In Gram-negative bacteria, a synergistic relationship between slow passive uptake of antibiotics across the outer membrane and active efflux transporters creates a permeability barrier, which efficiently reduces the effective concentrations of antibiotics in cells and, hence, their activities. To analyze the relative contributions of active efflux and the passive barrier to the activities of antibiotics, we constructed Escherichia coli strains with controllable permeability of the outer membrane. The strains expressed a large pore that does not discriminate between compounds on the basis of their hydrophilicity and sensitizes cells to a variety of antibacterial agents. We found that the efficacies of antibiotics in these strains were specifically affected by either active efflux or slow uptake, or both, and reflect differences in the properties of the outer membrane barrier, the repertoire of efflux pumps, and the inhibitory activities of antibiotics. Our results identify antibiotics which are the best candidates for the potentiation of activities through efflux inhibition and permeabilization of the outer membrane.
在革兰氏阴性菌中，抗生素通过外膜的缓慢被动摄取与主动外排转运体之间的协同关系形成了一个通透性屏障，这有效地降低了细胞内抗生素的有效浓度，从而降低了它们的活性。为了分析主动外排和被动屏障对抗生素活性的相对贡献，我们构建了外膜通透性可控的大肠杆菌菌株。这些菌株表达了一种大孔，该大孔不会根据化合物的亲水性对其进行区分，并使细胞对多种抗菌剂敏感。我们发现，这些菌株中抗生素的疗效受到主动外排、缓慢摄取或两者的特异性影响，反映了外膜屏障特性、外排泵种类和抗生素抑制活性的差异。我们的结果确定了哪些抗生素是通过抑制外排和使外膜通透化来增强活性的最佳候选药物。
