title: Membrane interaction of antimicrobial peptides using E. coli lipid extract as model bacterial cell membranes and SFG spectroscopy.
abstract: Supported lipid bilayers are used as a convenient model cell membrane system to study biologically important molecule-lipid interactions in situ. However, the lipid bilayer models are often simple and the acquired results with these models may not provide all pertinent information related to a real cell membrane. In this work, we use sum frequency generation (SFG) vibrational spectroscopy to study molecular-level interactions between the antimicrobial peptides (AMPs) MSI-594, ovispirin-1 G18, magainin 2 and a simple 1,2-dipalmitoyl-d62-sn-glycero-3-phosphoglycerol (dDPPG)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) bilayer. We compared such interactions to those between the AMPs and a more complex dDPPG/Escherichia coli (E. coli) polar lipid extract bilayer. We show that to fully understand more complex aspects of peptide-bilayer interaction, such as interaction kinetics, a heterogeneous lipid composition is required, such as the E. coli polar lipid extract. The discrepancy in peptide-bilayer interaction is likely due in part to the difference in bilayer charge between the two systems since highly negative charged lipids can promote more favorable electrostatic interactions between the peptide and lipid bilayer. Results presented in this paper indicate that more complex model bilayers are needed to accurately analyze peptide-cell membrane interactions and demonstrates the importance of using an appropriate lipid composition to study AMP interaction properties.
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: Soblosky
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA; Biophysics, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Ayyalusamy
authors.initials: A
authors.lastname: Ramamoorthy
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA; Biophysics, University of Michigan, Ann Arbor, MI 48109, USA. Electronic address: zhanc@umich.edu.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Chen
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D040761:Biomimetic Materials / Q000138:chemical synthesis*; D002462:Cell Membrane / Q000737:chemistry*; D002474:Cell-Free System; D004926:Escherichia coli / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008422:Materials Testing; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers
keywords: Antimicrobial peptide; Bacterial cell; Membrane mimetics; Peptide–lipid interactions; Sum frequency generation; Vibrational spectroscopy