title: Two interdependent mechanisms of antimicrobial activity allow for efficient killing in nylon-3-based polymeric mimics of innate immunity peptides.
abstract: Novel synthetic mimics of antimicrobial peptides have been developed to exhibit structural properties and antimicrobial activity similar to those of natural antimicrobial peptides (AMPs) of the innate immune system. These molecules have a number of potential advantages over conventional antibiotics, including reduced bacterial resistance, cost-effective preparation, and customizable designs. In this study, we investigate a family of nylon-3 polymer-based antimicrobials. By combining vesicle dye leakage, bacterial permeation, and bactericidal assays with small-angle X-ray scattering (SAXS), we find that these polymers are capable of two interdependent mechanisms of action: permeation of bacterial membranes and binding to intracellular targets such as DNA, with the latter necessarily dependent on the former. We systemically examine polymer-induced membrane deformation modes across a range of lipid compositions that mimic both bacteria and mammalian cell membranes. The results show that the polymers' ability to generate negative Gaussian curvature (NGC), a topological requirement for membrane permeation and cellular entry, in model Escherichia coli membranes correlates with their ability to permeate membranes without complete membrane disruption and kill E. coli cells. Our findings suggest that these polymers operate with a concentration-dependent mechanism of action: at low concentrations permeation and DNA binding occur without membrane disruption, while at high concentrations complete disruption of the membrane occurs. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, CA 90095, United States.
authors.forename: Michelle W
authors.initials: MW
authors.lastname: Lee
authors.affiliation: Department of Chemistry, University of Wisconsin, Madison, WI 53706, United States.
authors.forename: Saswata
authors.initials: S
authors.lastname: Chakraborty
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, CA 90095, United States.
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Schmidt
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, CA 90095, United States.
authors.forename: Rajan
authors.initials: R
authors.lastname: Murgai
authors.affiliation: Department of Chemistry, University of Wisconsin, Madison, WI 53706, United States.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Gellman
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, CA 90095, United States; Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, United States; California NanoSystems Institute, University of California, Los Angeles, CA 90095, United States. Electronic address: gclwong@seas.ucla.edu.
authors.forename: Gerard C L
authors.initials: GC
authors.lastname: Wong
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D001424:Bacterial Infections / Q000188:drug therapy; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects*; D008051:Lipid Bilayers / Q000737:chemistry; D009757:Nylons / Q000737:chemistry; D011108:Polymers / Q000737:chemistry
chemical_list: D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers; D009757:Nylons; D011108:Polymers
keywords: antimicrobial peptides; innate immunity; membrane curvature; membrane permeation; peptide–lipid interactions; pore formation
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