title: Interaction of hydrophobic and amphipathic antimicrobial peptides with lipid bicelles.
abstract: Bicelles are model membrane systems that can be macroscopically oriented in a magnetic field at physiological temperature. The macroscopic orientation of bicelles allows to detect, by means of magnetic resonance spectroscopies, small changes in the order of the bilayer caused by solutes interacting with the membrane. These changes would be hardly detectable in isotropic systems such as vesicles or micelles. The aim of this work is to show that bicelles represent a convenient tool to investigate the behavior of antimicrobial peptides (AMPs) interacting with membranes, using electron paramagnetic resonance (EPR) spectroscopy. We performed the EPR experiments on spin-labeled bicelles using various AMPs of different length, charge, and amphipathicity: alamethicin, trichogin GA IV, magainin 2, HP(2-20), and HPA3. We evaluated the changes in the order parameter of the spin-labeled lipids as a function of the peptide-to-lipid ratio. We show that bicelles labeled at position 5 of the lipid chains are very sensitive to the perturbation induced by the AMPs even at low peptide concentrations. Our study indicates that peptides that are known to disrupt the membrane by different mechanisms (i.e., alamethicin vs magainin 2) show very distinct trends of the order parameter as a function of peptide concentration. Therefore, spin-labeled bicelles proved to be a good system to evaluate the membrane disruption mechanism of new AMPs.
authors.affiliation: Department of Chemistry, University of Padova, via Marzolo 1, Padova, 35131, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Bortolus
authors.forename: Annalisa
authors.initials: A
authors.lastname: Dalzini
authors.forename: Claudio
authors.initials: C
authors.lastname: Toniolo
authors.forename: Kyung-Soo
authors.initials: KS
authors.lastname: Hahm
authors.forename: Anna Lisa
authors.initials: AL
authors.lastname: Maniero
mesh_terms: D000408:Alamethicin / Q000737:chemistry; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D055666:Lipopeptides / Q000737:chemistry*; D008823:Micelles; D010742:Phospholipid Ethers / Q000737:chemistry*
chemical_list: C052298:1,2-dihexadecyl-sn-glycero-3-phosphocholine; D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers; D055666:Lipopeptides; D008823:Micelles; D010742:Phospholipid Ethers; C116419:trichogin GA IV; D000408:Alamethicin; D004134:Dimyristoylphosphatidylcholine
keywords: EPR; antimicrobial peptides; bicelles; membrane interaction; order parameter; peptaibiotics