Document Type
Article
Publication Date
6-13-2024
Abstract
Antimicrobial peptides (AMPs) are being explored as a potential strategy to combat antibiotic resistance due to their ability to reduce susceptibility to antibiotics. This study explored whether the [R4W4] peptide mode of action is bacteriostatic or bactericidal using modified two-fold serial dilution and evaluating the synergism between gentamicin and [R4W4] against Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) by a checkered board assay. [R4W4] exhibited bactericidal activity against bacterial isolates (MBC/MIC ≤ 4), with a synergistic effect with gentamicin against E. coli (FICI = 0.3) but not against MRSA (FICI = 0.75). Moreover, we investigated the mechanism of action of [R4W4] against MRSA by applying biophysical assays to evaluate zeta potential, cytoplasmic membrane depolarization, and lipoteichoic acid (LTA) binding affinity. [R4W4] at a 16 mg/mL concentration stabilized the zeta potential of MRSA −31 ± 0.88 mV to −8.37 mV. Also, [R4W4] at 2 × MIC and 16 × MIC revealed a membrane perturbation process associated with concentration-dependent effects. Lastly, in the presence of BODIPY-TR-cadaverine (BC) fluorescence dyes, [R4W4] exhibited binding affinity to LTA comparable with melittin, the positive control. In addition, the antibacterial activity of [R4W4] against MRSA remained unchanged in the absence and presence of LTA, with an MIC of 8 µg/mL. Therefore, the [R4W4] mechanism of action is deemed bactericidal, involving interaction with bacterial cell membranes, causing concentration-dependent membrane perturbation. Additionally, after 30 serial passages, there was a modest increment of MRSA strains resistant to [R4W4] and a change in antibacterial effectiveness MIC [R4W4] and vancomycin by 8 and 4 folds with a slight change in Levofloxacin MIC 1 to 2 µg/mL. These data suggest that [R4W4] warrants further consideration as a potential AMP.
Recommended Citation
Akinwale, A.D.; Parang, K.; Tiwari, R.K.; Yamaki, J. Mechanistic Study of Antimicrobial Effectiveness of Cyclic Amphipathic Peptide [R4W4] against Methicillin-Resistant Staphylococcus aureus Clinical Isolates. Antibiotics 2024, 13, 555. https://doi.org/10.3390/antibiotics13060555
Copyright
The authors
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Included in
Amino Acids, Peptides, and Proteins Commons, Bacterial Infections and Mycoses Commons, Medicinal and Pharmaceutical Chemistry Commons, Other Pharmacy and Pharmaceutical Sciences Commons, Therapeutics Commons
Comments
This article was originally published in Antibiotics, volume 13, issue 6, in 2024. https://doi.org/10.3390/antibiotics13060555