Abstract
Antibiotic resistance poses an immediate and growing threat to human health. Multidrug efflux pumps are promising targets for overcoming antibiotic resistance with small-molecule therapeutics. Previously, we identified a diaminoquinoline acrylamide, NSC-33353, as a potent inhibitor of the AcrAB-TolC efflux pump in Escherichia coli. This inhibitor potentiates the antibacterial activities of novobiocin and erythromycin upon binding to the membrane fusion protein AcrA. It is also a substrate for efflux and lacks appreciable intrinsic antibacterial activity of its own in wild-type cells. Here, we have modified the substituents of the cinnamoyl group of NSC-33353, giving rise to analogs that retain the ability to inhibit efflux, lost the features of the efflux substrates, and gained antibacterial activity in wild-type cells. The replacement of the cinnamoyl group with naphthyl isosteres generated compounds that lack antibacterial activity but are both excellent efflux pump inhibitors and substrates. Surprisingly, these inhibitors potentiate the antibacterial activity of novobiocin but not erythromycin. Surface plasmon resonance experiments and molecular docking suggest that the replacement of the cinnamoyl group with naphthyl shifts the affinity of the compounds away from AcrA to the AcrB transporter, making them better efflux substrates and changing their mechanism of inhibition. These results provide new insights into the duality of efflux substrate/inhibitor features in chemical scaffolds that will facilitate the development of new efflux pump inhibitors.
| Original language | English |
|---|---|
| Pages (from-to) | 2650-2665 |
| Number of pages | 16 |
| Journal | ACS Infectious Diseases |
| Volume | 7 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 10 2021 |
Funding
The authors thank the National Institute of Health, AI052293 (H.I.Z.) and AI136799 (H.I.Z., G.M., E.M., A.V.V., P.R., V.V.R., and J.K.W.), who supported this work. G.M., E.M., A.V.V., and P.R. acknowledge technical support by Giovanni Serra and Andrea Bosin (University of Cagliari). C.J.C. was supported by a National Science Foundation Graduate Research Fellowship under Grant No. 2017219379. This research used resources of the Compute and Data Environment for Science (CADES) at Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. We also gratefully acknowledge Dr. Fahu He and the St. Louis University NMR facility for acquiring C samples on the 700 MHz NMR. 13 The authors thank the National Institute of Health AI052293 (H.I.Z.) and AI136799 (H.I.Z., G.M., E.M., A.V.V., P.R. V.V.R., and J.K.W.), who supported this work. G.M., E.M., A.V.V. and P.R. acknowledge technical support by Giovanni Serra and Andrea Bosin (University of Cagliari). C.J.C. was supported by a National Science Foundation Graduate Research Fellowship under Grant No. 2017219379. This research used resources of the Compute and Data Environment for Science (CADES) at Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. We also gratefully acknowledge Dr. Fahu He and the St. Louis University NMR facility for acquiring 13C samples on the 700 MHz NMR.
| Funders | Funder number |
|---|---|
| National Science Foundation | 2017219379 |
| National Institutes of Health | AI136799 |
| U.S. Department of Energy | DE-AC05-00OR22725 |
| National Institute of Allergy and Infectious Diseases | R01AI052293 |
| Office of Science | |
| Oak Ridge National Laboratory | |
| Università degli Studi di Cagliari |
Keywords
- AcrAB-TolC
- Escherichia coli
- antibiotic permeation
- antibiotic potentiation
- efflux pump inhibitors
