title: Influence of antimicrobial peptides on the formation of nonlamellar lipid mesophases.
abstract: We have studied the influence of four antimicrobial peptides of different secondary and ternary structure--melittin (Mel), protegrin-1 (PG-1), peptidyl-glycylleucine-carboxyamide (PGLa), and gramicidin S (GS)--on the lamellar-to-nonlamellar transition of palmitoyloleoyl phosphatidylethanolamine (POPE) applying differential scanning calorimetry and small-angle X-ray diffraction. None of the peptides studied led to the formation of an inverted hexagonal phase observed for pure POPE at high temperatures. Instead either cubic or lamellar phases were stabilized to different degrees. GS was most effective in inducing a cubic phase, whereas Mel fully stabilized the lamellar phase. The behavior of POPE in the presence of PG-1 and PGLa was intermediate to GS and Mel. In addition to the known role of membrane elasticity we propose two mechanisms, which cause stabilization of the lamellar phase: electrostatic repulsion and lipid/peptide pore formation. Both mechanisms prevent transmembrane contact required to form either an inverted hexagonal phase or fusion pores, as precursors of the cubic phase.
authors.affiliation: Institute of Biophysics and Nanosystems Research, Austrian Academy of Sciences, Schmiedlstrasse 6, A 8042 Graz, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Hickel
authors.forename: Sabine
authors.initials: S
authors.lastname: Danner-Pongratz
authors.forename: Heinz
authors.initials: H
authors.lastname: Amenitsch
authors.forename: Gabor
authors.initials: G
authors.lastname: Degovics
authors.forename: Michael
authors.initials: M
authors.lastname: Rappolt
authors.forename: Karl
authors.initials: K
authors.lastname: Lohner
authors.forename: Georg
authors.initials: G
authors.lastname: Pabst
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D006096:Gramicidin / Q000737:chemistry; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D008555:Melitten / Q000737:chemistry; D008958:Models, Molecular; D044367:Phase Transition; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D011498:Protein Precursors / Q000737:chemistry; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014961:X-Ray Diffraction
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D008055:Lipids; D008081:Liposomes; C088254:PGLa prepropeptide; D010714:Phosphatidylethanolamines; D011498:Protein Precursors; C094880:protegrin-1; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine; D006096:Gramicidin; D008555:Melitten