title: Lactoferrin-derived antimicrobial peptide induces a micellar cubic phase in a model membrane system.
abstract: The observation of a micellar cubic phase is reported for a mixture of an antimicrobial peptide from the Lactoferrin family, LFampin 265-284, and a model membrane system of dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol (3:1), as derived from small-angle x-ray diffraction (SAXD) measurements. The system shows remarkable thermotropic polymorphism: the peptide disrupts the lipid bilayer, forming a cubic phase of the space group Pm3n (t < 28°C), and as the temperature increases it shows a complex phase behavior (not fully clarified by SAXD). The onset, volume fraction of each phase, and phase parameters are seen to vary with peptide/lipid ratio and temperature. The obtained SAXD data represent the first experimental evidence, to our knowledge, of a micellar cubic phase in the context of antimicrobial peptide/membrane interaction. We propose that the micellization of the membrane according to the carpet model, for long proposed as a possible mechanism of action, can go through the formation of a cubic micellar phase.
authors.affiliation: Centro de Investigação em Química (UP), Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Porto, Portugal. mbastos@fc.up.pt
authors.forename: Margarida
authors.initials: M
authors.lastname: Bastos
authors.forename: Tânia
authors.initials: T
authors.lastname: Silva
authors.forename: Vitor
authors.initials: V
authors.lastname: Teixeira
authors.forename: Kamran
authors.initials: K
authors.lastname: Nazmi
authors.forename: Jan G M
authors.initials: JG
authors.lastname: Bolscher
authors.forename: Sérgio S
authors.initials: SS
authors.lastname: Funari
authors.forename: Daniela
authors.initials: D
authors.lastname: Uhríková
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology*; D002462:Cell Membrane / Q000737:chemistry* / Q000187:drug effects*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D007781:Lactoferrin / Q000737:chemistry*; D008823:Micelles; D010715:Phosphatidylglycerols / Q000737:chemistry; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D023181:Antimicrobial Cationic Peptides; D008823:Micelles; D010715:Phosphatidylglycerols; C002773:dimyristoylphosphatidylglycerol; D007781:Lactoferrin; D004134:Dimyristoylphosphatidylcholine