title: Identification of the initial binding sites of alphas2-casein f(183-207) and effect on bacterial membranes and cell morphology.
abstract: The aim of this work was to identify the initial binding sites to the bacterial membranes of the antimicrobial peptide alphas2-casein f(183-207) and also to acquire further insight into membrane permeabilization of this peptide. Furthermore, cell morphology was studied by transmission electron microscopy. In all the experiments, bovine LFcin was employed as a comparison. Results showed that initial binding sites of alphas2-casein f(183-207) peptide were lipoteichoic acid in Gram-positive bacteria and lipopolysaccharide in Gram-negative. The peptide was able to permeabilize the outer and inner membranes. Moreover, the alphas2-casein peptide f(183-207) generated pores in the outer membrane of Gram-negative bacteria and in the cell wall of Gram-positive bacteria. In the Gram-negative bacteria, f(183-207) originated cytoplasm condensation, and in the Gram-positive bacteria the cytoplasmic content leaked into the extracellular medium. Furthermore, the experiments of inner and outer membrane permeabilization performed with LFcin-B showed that this peptide also has the ability to permeabilize both the inner and outer membranes.
authors.affiliation: Instituto de Fermentaciones Industriales (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
authors.forename: Iván
authors.initials: I
authors.lastname: López-Expósito
authors.forename: Lourdes
authors.initials: L
authors.lastname: Amigo
authors.forename: Isidra
authors.initials: I
authors.lastname: Recio
mesh_terms: D000818:Animals; D001665:Binding Sites; D002364:Caseins / Q000378:metabolism / Q000494:pharmacology; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D048430:Cell Shape; D004926:Escherichia coli / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D013210:Staphylococcus / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D013682:Teichoic Acids / Q000378:metabolism
chemical_list: D002364:Caseins; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D013682:Teichoic Acids; C121341:alpha(S2)-casein (183-207); C009900:lipoteichoic acid