Molecular Dynamics Study of Surfactin Interaction with Lipid Bilayer Membranes

Background: Surfactin is a cyclic heptapeptide that is closed by a β-hydroxy fatty acid chain. This potent biosurfactant is produced by different Bacillus subtilis strains. This lipopeptide has numerous attractive biological activities, including antibacterial, antiviral, antimycoplasma, hemolytic, and other different and powerful surface and interface activities. Methods: Understanding how surfactin binds to different membranes and its mechanism of action can help us modify and optimize its structure to improve the potential efficacy of this lipopeptide in the future. For this purpose, we studied the interaction of this lipopeptide with two types of lipid bilayer models, including palmitoyl-oleoyl-glycero- phosphocholine (POPC) and palmitoyl-oleoyl-phosphtidylglycerol (POPG) as the prokaryotic and eukaryotic membrane models, respectively. Results: The obtained data have shown that the tendency of surfactin for these membranes is different. According to the analysis, this molecule binds to both membranes peripherally, and its interaction with the negative membrane is also more potent compared to the zwitterionic membrane. Moreover, we found that surfactin destabilized POPG more than POPC. This suggests that surfactin may act by modifying the membrane’s bulk physical properties. Conclusions: As a final point, this study has shown that surfactin has different behaviors in the eukaryotic and prokaryotic cell membranes and can modify and amplify its action in order to use it for antibacterial drugs.