title: Synergistic effects of the membrane actions of cecropin-melittin antimicrobial hybrid peptide BP100.
abstract: BP100 (KKLFKKILKYL-NH(2)) is a short cecropin A-melittin hybrid peptide, obtained through a combinatorial chemistry approach, which is highly effective in inhibiting both the in vitro and in vivo growth of economically important plant pathogenic Gram-negatives. The intrinsic Tyr fluorescence of BP100 was taken advantage of to study the peptide's binding affinity and damaging effect on phospholipid bilayers modeling the bacterial and mammalian cytoplasmic membranes. In vitro cytotoxic effects of this peptide were also studied on mammalian fibroblast cells. Results show a stronger selectivity of BP100 toward anionic bacterial membrane models as indicated by the high obtained partition constants, one order of magnitude greater than for the neutral mammalian membrane models. For the anionic systems, membrane saturation was observed at high peptide/lipid ratios and found to be related with BP100-induced vesicle permeabilization, membrane electroneutrality, and vesicle aggregation. Occurrence of BP100 translocation was unequivocally detected at both high and low peptide/lipid ratios using a novel and extremely simple method. Moreover, cytotoxicity against mammalian models was reached at a concentration considerably higher than the minimum inhibitory concentration. Our findings unravel the relationships among the closely coupled processes of charge neutralization, permeabilization, and translocation in the mechanism of action of antimicrobial peptides.
authors.affiliation: Laboratori d'Innovació en Processos i Productes de Síntesi Orgànica, Departament de Química, Universitat de Girona, Girona, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Ferre
authors.forename: Manuel N
authors.initials: MN
authors.lastname: Melo
authors.forename: Ana D
authors.initials: AD
authors.lastname: Correia
authors.forename: Lidia
authors.initials: L
authors.lastname: Feliu
authors.forename: Eduard
authors.initials: E
authors.lastname: Bardají
authors.forename: Marta
authors.initials: M
authors.lastname: Planas
authors.forename: Miguel
authors.initials: M
authors.lastname: Castanho
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D002463:Cell Membrane Permeability; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D006224:Cricetinae; D005347:Fibroblasts / Q000378:metabolism; D005453:Fluorescence; D008027:Light; D008051:Lipid Bilayers / Q000378:metabolism*; D017711:Nonlinear Dynamics; D009842:Oligopeptides / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D012044:Regression Analysis; D012542:Scattering, Radiation
chemical_list: D000900:Anti-Bacterial Agents; D008051:Lipid Bilayers; D009842:Oligopeptides; C540525:lysyl-lysyl-leucyl-phenylalanyl-lysyl-lysyl-isoleucyl-leucyl-lysyl-tyrosyl-leucinamide