Michael J Wilhelm, Mohammad Sharifian Gh, Bruk Mensa, Gabriella L Howell, William F DeGrado, Hai-Lung Dai
{"title":"Antimicrobial Activity of Brilacidin against <i>E. coli</i>.","authors":"Michael J Wilhelm, Mohammad Sharifian Gh, Bruk Mensa, Gabriella L Howell, William F DeGrado, Hai-Lung Dai","doi":"10.1021/acsinfecdis.5c00023","DOIUrl":null,"url":null,"abstract":"<p><p>Brilacidin (BRI) is a potent small-molecule mimic of antimicrobial peptides that has demonstrated efficacy against various pathogens. To better understand its antimicrobial mechanism of action, we investigated the interactions of BRI with the membranes of <i>Escherichia coli</i>. Specifically, the surface-sensitive nonlinear optical technique, second harmonic laser scattering (SHS), was used to monitor BRI-induced changes in the permeabilities of the dual phospholipid membranes of <i>E. coli</i> by measuring the adsorption and transport of a membrane-permeable indicator molecule (the quaternary ammonium cation, malachite green). Following exposure to 0.6 to 12× MIC BRI, the permeability of the outer membrane was shown to increase 2-fold. Conversely, the permeability of the inner membrane was shown to exhibit more complicated behavior: Permeability increased for near-MIC doses (≤3× MIC) of BRI but was significantly reduced for higher concentrations. The latter is consistent with the depolarization of the inner membrane, which was previously predicted in a computational study. The interpretation of the SHS results was corroborated with complementary assays that measure the permeability of small polar molecules to periplasmic versus cytosolic enzymes, as well as ATP luminescence and Western blot assays (for accumulation of secreted protein precursors). It is suggested that the mechanism of action of BRI against <i>E. coli</i> consists of a sequential and complementary attack on both membranes, beginning with an immediate and persistent increase in the permeability of the outer membrane and followed by likely depolarization of the inner membrane. This study also illustrates a new quantitative capability for monitoring antimicrobial interactions by using time-resolved SHS.</p>","PeriodicalId":17,"journal":{"name":"ACS Infectious Diseases","volume":" ","pages":"1486-1496"},"PeriodicalIF":3.8000,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Infectious Diseases","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1021/acsinfecdis.5c00023","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/6/3 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"CHEMISTRY, MEDICINAL","Score":null,"Total":0}
引用次数: 0
Abstract
Brilacidin (BRI) is a potent small-molecule mimic of antimicrobial peptides that has demonstrated efficacy against various pathogens. To better understand its antimicrobial mechanism of action, we investigated the interactions of BRI with the membranes of Escherichia coli. Specifically, the surface-sensitive nonlinear optical technique, second harmonic laser scattering (SHS), was used to monitor BRI-induced changes in the permeabilities of the dual phospholipid membranes of E. coli by measuring the adsorption and transport of a membrane-permeable indicator molecule (the quaternary ammonium cation, malachite green). Following exposure to 0.6 to 12× MIC BRI, the permeability of the outer membrane was shown to increase 2-fold. Conversely, the permeability of the inner membrane was shown to exhibit more complicated behavior: Permeability increased for near-MIC doses (≤3× MIC) of BRI but was significantly reduced for higher concentrations. The latter is consistent with the depolarization of the inner membrane, which was previously predicted in a computational study. The interpretation of the SHS results was corroborated with complementary assays that measure the permeability of small polar molecules to periplasmic versus cytosolic enzymes, as well as ATP luminescence and Western blot assays (for accumulation of secreted protein precursors). It is suggested that the mechanism of action of BRI against E. coli consists of a sequential and complementary attack on both membranes, beginning with an immediate and persistent increase in the permeability of the outer membrane and followed by likely depolarization of the inner membrane. This study also illustrates a new quantitative capability for monitoring antimicrobial interactions by using time-resolved SHS.
期刊介绍:
ACS Infectious Diseases will be the first journal to highlight chemistry and its role in this multidisciplinary and collaborative research area. The journal will cover a diverse array of topics including, but not limited to:
* Discovery and development of new antimicrobial agents — identified through target- or phenotypic-based approaches as well as compounds that induce synergy with antimicrobials.
* Characterization and validation of drug target or pathways — use of single target and genome-wide knockdown and knockouts, biochemical studies, structural biology, new technologies to facilitate characterization and prioritization of potential drug targets.
* Mechanism of drug resistance — fundamental research that advances our understanding of resistance; strategies to prevent resistance.
* Mechanisms of action — use of genetic, metabolomic, and activity- and affinity-based protein profiling to elucidate the mechanism of action of clinical and experimental antimicrobial agents.
* Host-pathogen interactions — tools for studying host-pathogen interactions, cellular biochemistry of hosts and pathogens, and molecular interactions of pathogens with host microbiota.
* Small molecule vaccine adjuvants for infectious disease.
* Viral and bacterial biochemistry and molecular biology.