Abstract
Liposomes constructed from Escherichia coli membrane lipids were used as a pseudo-stationary phase in capillary electrophoresis and immobilised liposome chromatography to evaluate the interaction between antibacterial peptide (ABP) Apep10 and bacterial membrane lipids. The peptide mobility decreased as the concentration of liposomes increased, providing evidence for the existence of this interaction. The binding constant between Apep10 and the Escherichia coli membranes lipid liposome was higher than that of Apep10 with a mixed phospholipids liposome at the same temperature. The capillary electrophoresis results indicate that the binding ability of Apep10 with a liposome was dependent on the liposome’s lipid compositions. Thermodynamic analysis by immobilised liposome chromatography indicated that hydrophobic and electrostatic effects contributed to the partitioning of Apep10 in the membrane lipids. The liposomes constructed from bacterial membrane lipid were more suitable as the model membranes used to study dynamic ABP/membrane interactions than those constructed from specific ratios of particular phospholipids, with its more biomimetic phospholipid composition and contents. This study provides an appropriate model for the evaluation of ABP-membrane interactions.
Highlights
Antibacterial peptides (ABPs) have attracted much attention due to their potential to overcome bacterial resistance and are promising candidates for novel antibiotics [1], [2]
We developed an effective method of Escherichia coli cell membrane chromatography for the separation of ABPs, based on the affinity interaction between ABPs and bacterial cell membrane liposomes [18]
Some ABPs may penetrate the lipid bilayer, and others may bind to the head group region parallel to the plane of the bilayer; they may further perturb the hydrophobic region and induce a rapid flip-flopping of the phospholipids
Summary
Antibacterial peptides (ABPs) have attracted much attention due to their potential to overcome bacterial resistance and are promising candidates for novel antibiotics [1], [2]. It is well established that the first stage of ABPs’ action is to combine with the bacterial cell membrane [3–5]. Knowledge of this interaction is vital to understand their antibacterial mechanism. The natural cell membrane has a very short lifespan, which makes it an imperfect candidate for research. To overcome this shortcoming, self-assembled vesicles known as liposomes have been widely used as model membranes, due to the structural similarities between liposomes and the natural cell membrane, both of which are phospholipid bilayers [6–9].
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