Permeabilizing action of an antimicrobial lactoferricin-derived peptide onbacterial and artificial membranes

A synthetic peptide (23 residues) that includes the antibacterial and lipop olysaccharide-binding regions of human lactoferricin, an antimicrobial sequ ence of lactoferrin, was used to study its action on cytoplasmic membrane o f Escherichia coli 0111 and E, coli phospholipid vesicles. The peptide caus ed a depolarization of the bacterial cytoplasmic membrane, loss of the pH g radient, and a bactericidal effect on E, coli, Similarly, the binding of th e peptide to liposomes dissipated previously created transmembrane electric al and pH gradients. The dramatic consequences of the transmembrane ion flu x during the peptide exposure indicate that the adverse effect on bacterial cells occurs at the bacterial inner membrane. (C) 1999 Federation of Europ ean Biochemical Societies.