title: Comparative functional properties of engineered cationic antimicrobial peptides consisting exclusively of tryptophan and either lysine or arginine.
abstract: We previously reported a series of de novo engineered cationic antibiotic peptides (eCAPs) consisting exclusively of arginine and tryptophan (WR) that display potent activity against diverse multidrug-resistant (MDR) bacterial strains. In this study, we sought to examine the influence of arginine compared to lysine on antibacterial properties by direct comparison of the WR peptides (8-18 residues) with a parallel series of engineered peptides containing only lysine and tryptophan. WR and WK series were compared for antibacterial activity by bacterial killing and growth inhibition assays and for mechanism of peptide-bacteria interactions by surface plasmon resonance and flow cytometry. Mammalian cytotoxicity was also assessed by flow cytometry, haemolytic and tetrazolium-based assays. The shortest arginine-containing peptides (8 and 10 mers) displayed a statistically significant increase in activity compared to the analogous lysine-containing peptides. The WR and WK peptides achieved maximum antibacterial activity at the 12-mer peptide (WK12 or WR12). Further examination of antibacterial mechanisms of the optimally active 12-mer peptides using surface plasmon resonance and flow cytometry demonstrates stronger interactions with Pseudomonasaeruginosa, greater membrane permeabilizing activity, and lower inhibitory effects of divalent cations on activity and membrane permeabilization properties of WR12 compared to WK12 (P < 0.05). Importantly, WK12 and WR12 displayed similar negligible haemolytic and cytotoxic effects at peptide concentrations up to ten times the MIC or 20 times the minimum bactericidal concentration. Thus, arginine, compared to lysine, can indeed yield enhanced antibacterial activity to minimize the required length to achieve functional antimicrobial peptides.
authors.affiliation: Center for Vaccine Research and Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Berthony
authors.initials: B
authors.lastname: Deslouches
authors.affiliation: Center for Vaccine Research and Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Mary L
authors.initials: ML
authors.lastname: Hasek
authors.affiliation: Center for Vaccine Research and Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Jodi K
authors.initials: JK
authors.lastname: Craigo
authors.affiliation: Center for Vaccine Research and Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Steckbeck
authors.affiliation: Center for Vaccine Research and Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Montelaro
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology*; D001120:Arginine / Q000737:chemistry*; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D008239:Lysine / Q000737:chemistry*; D008264:Macrophages / Q000187:drug effects; D011485:Protein Binding; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D023181:Antimicrobial Cationic Peptides; D014364:Tryptophan; D001120:Arginine; D008239:Lysine