title: Mode of action of the antimicrobial peptide aureocin A53 from Staphylococcus aureus.
abstract: We investigated the mode of action of aureocin A53 on living bacterial cells and model membranes. Aureocin A53 acted bactericidally against Staphylococcus simulans 22, with >90% of the cells killed within a few minutes. Cell death was followed by lysis, as indicated by a clearing of the cell suspension and Gram staining. Aureocin A53 rapidly dissipated the membrane potential and simultaneously stopped biosynthesis of DNA, polysaccharides, and protein. Aureocin A53 induced a rapid release of preaccumulated glutamate and Rb(+). Experiments on model membranes demonstrated that aureocin A53 provoked significant leakage of carboxyfluorescein (CF) exclusively from acidic liposomes but only at relatively high concentrations (0.5 to 8 mol%). Thus, the bactericidal activity of aureocin A53 derives from membrane permeation via generalized membrane destruction rather than by formation of discrete pores within membranes. Tryptophan emission fluorescence spectroscopy demonstrated interaction of aureocin A53 with both acidic and neutral membranes, as indicated by similar blue shifts. Since there was no significant aureocin A53-induced CF leakage from neutral liposomes, its appears that the peptide does interact with neutral lipids without provoking membrane damage.
authors.affiliation: Departamento de Microbiologia Geral, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Daili Jacqueline Aguilar
authors.initials: DJ
authors.lastname: Netz
authors.forename: Maria do Carmo de Freire
authors.initials: Mdo C
authors.lastname: Bastos
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Sahl
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D001692:Biological Transport / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects*; D016984:Enterococcus faecium / Q000187:drug effects; D008081:Liposomes / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D016982:Micrococcus luteus / Q000187:drug effects; D010455:Peptides / Q000302:isolation & purification / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D008081:Liposomes; D010455:Peptides; C469333:aureocin A53, Staphylococcus aureus; D014364:Tryptophan