The membrane – peptide insertion behavior of an artificial antimicrobial peptide analogue in liposomes, planar free-standing
bilayer and planar lipid membranes supported by a crystalline bacterial surface layer, termed S-layer, was investigated. The template for
this peptide was peptidyl-glycine-leucine-carboxyamide (PGLa) where all lysine residues were replaced by glutamic acid resulting in a
negatively charged analogue termed PGLa(-). Zeta potential measurements and calcein release experiments on liposomes revealed that
the insertion of PGLa(-) can be compared to that of native antimicrobial peptides. Patch clamp recordings on free-standing lipid membranes
provided evidence of pore formation at a lipid to peptide ratio (L/P) of 1600 with a single pore conductance of 25 pS. However,
also a lower conductance at a high L/P (3200) was observed which might be explained by membrane disordering effects caused by
PGLa(-) interaction. In line with other studies on the action of membrane active peptides, the rupture of the lipid membrane was strongly
influenced by the peptide concentration. S-layer supported lipid membranes were utilized to perform combined surface-sensitive (quartz
crystal microbalance with dissipation measurements) and electrical (impedance spectroscopy) measurements. These data evidenced not
only the attachment and/or insertion of PGLa(-) in the supported lipid membrane but also indicated toroidal pore formation in a concentration
dependent fashion. Hence, S-layer supported lipid membranes constitute a promising platform for studying the interaction and insertion
of antimicrobial peptides.
Keywords: Antimicrobial peptide, electrochemical quartz crystal microbalance with dissipation monitoring, model lipid membranes, nanobiotechnology,
patch-clamp, peptidyl-glycine-leucine-carboxyamide, S-layer supported bilayer.
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