Abstract
Resistance or tolerance to traditional antibiotics is a challenging issue in antimicrobial chemotherapy. Moreover, traditional bactericidal antibiotics kill only actively growing bacterial cells, whereas nongrowing metabolically inactive cells are tolerant to and therefore “persist” in the presence of legacy antibiotics. Here, we report that the diarylurea derivative PQ401, previously characterized as an inhibitor of the insulin-like growth factor I receptor, kills both antibiotic-resistant and nongrowing antibiotic-tolerant methicillin-resistant Staphylococcus aureus (MRSA) by lipid bilayer disruption. PQ401 showed several beneficial properties as an antimicrobial lead compound, including rapid killing kinetics, low probability for resistance development, high selectivity to bacterial membranes compared to mammalian membranes, and synergism with gentamicin. In contrast to well-studied membrane-disrupting cationic antimicrobial low-molecular-weight compounds and peptides, molecular dynamic simulations supported by efficacy data demonstrate that the neutral form of PQ401 penetrates and subsequently embeds into bacterial lipid bilayers more effectively than the cationic form. Lastly, PQ401 showed efficacy in both the Caenorhabditis elegans and Galleria mellonella models of MRSA infection. These data suggest that PQ401 may be a lead candidate for repurposing as a membrane-active antimicrobial and has potential for further development as a human antibacterial therapeutic for difficult-to-treat infections caused by both drug-resistant and-tolerant S. aureus. IMPORTANCE Membrane-damaging antimicrobial agents have great potential to treat multidrug-resistant or multidrug-tolerant bacteria against which conventional antibiotics are not effective. However, their therapeutic applications are often hampered due to their low selectivity to bacterial over mammalian membranes or their potential for cross-resistance to a broad spectrum of cationic membrane-active antimicrobial agents. We discovered that the diarylurea derivative compound PQ401 has antimicrobial potency against multidrug-resistant and multidrug-tolerant Staphylococcus aureus. PQ401 selectively disrupts bacterial membrane lipid bilayers in comparison to mammalian membranes. Unlike cationic membrane-active antimicrobials, the neutral form of PQ401 rather than its cationic form exhibits maximum membrane activity. Overall, our results demonstrate that PQ401 could be a promising lead compound that overcomes the current limitations of membrane selectivity and cross-resistance. Also, this work provides deeper insight into the design and development of new noncharged membrane-targeting therapeutics to combat hard-to-cure bacterial infections..
| Original language | English (US) |
|---|---|
| Article number | e01140-20 |
| Pages (from-to) | 1-18 |
| Number of pages | 18 |
| Journal | mBio |
| Volume | 11 |
| Issue number | 3 |
| DOIs | |
| State | Published - 2020 |
Funding
This study was supported by National Institutes of Health grant P01AI083214 to F.M.A. and E.M. W.K. is supported by the National Research Foundation of Korea grants funded by the South Korean government (MSIT) (2020R1C1C1008842, 2018R1A5A2025286, and 2017M3A9E4077234). G.Z. and H.G. acknowledge support from a start-up grant from the Nanyang Technological University and Institute of High Performance Computing, A*STAR, Singapore. Molecular dynamics simulations reported were performed on resources of the National Supercomputing Centre, Singapore (http://www.nscc.sg). W.K. conducted compound screening. W.K., W.P., S.M.K., R.K., S.L., K.L., and I.E. designed, performed, and analyzed MIC assays, time-kill assays, membrane permeability assays, hemolysis assays, and animal infection assays. W.K., N.F., H.A.F., and P.M.V. designed, performed, and analyzed GUV experiments. G.Z. and H.G. designed, performed, and analyzed MD simulation. W.K., P.M.V., H.G., F.M.A., and E.M. contributed reagents/materials/analysis tools. F.M.A. provided strategic guidance. E.M. supervised the project. W.K., G.Z., H.G., F.M.A., and E.M. wrote the manuscript. F.M.A. and E.M. have financial interests in Genma Biosciences, Inc., and Octagon Therapeutics, Inc., companies that were previously engaged in developing antimicrobial compounds. E.M.’s and F.M.A.’s interests were reviewed and are managed by Rhode Island Hospital (E.M.) and Massachusetts General Hospital and Partners HealthCare (F.M.A.) in accordance with their conflict of interest policies. The remaining authors declare no competing financial interests. This study was supported by National Institutes of Health grant P01AI083214 to F.M.A. and E.M. W.K. is supported by the National Research Foundation of Korea grants funded by the South Korean government (MSIT) (2020R1C1C1008842, 2018R1A5A2025286, and 2017M3A9E4077234). G.Z. and H.G. acknowledge support from a start-up grant from the Nanyang Technological University and Institute of High Performance Computing, A*STAR, Singapore. Molecular dynamics simulations reported were performed on resources of the National Supercomputing Centre, Singapore (http://www.nscc.sg).
Keywords
- Antibiotic
- Antibiotic tolerance
- Antimicrobial resistance
- Bacterial persister
- Caenorhabditis elegans
- MRSA
- Membrane-active agent
- Membrane-active antimicrobials
- Persisters
ASJC Scopus subject areas
- Virology
- Microbiology