title: N-acylated peptides derived from human lactoferricin perturb organization of cardiolipin and phosphatidylethanolamine in cell membranes and induce defects in Escherichia coli cell division.
abstract: Two types of recently described antibacterial peptides derived from human lactoferricin, either nonacylated or N-acylated, were studied for their different interaction with membranes of Escherichia coli in vivo and in model systems. Electron microscopy revealed striking effects on the bacterial membrane as both peptide types induced formation of large membrane blebs. Electron and fluorescence microscopy, however demonstrated that only the N-acylated peptides partially induced the generation of oversized cells, which might reflect defects in cell-division. Further a different distribution of cardiolipin domains on the E. coli membrane was shown only in the presence of the N-acylated peptides. The lipid was distributed over the whole bacterial cell surface, whereas cardiolipin in untreated and nonacylated peptide-treated cells was mainly located at the septum and poles. Studies with bacterial membrane mimics, such as cardiolipin or phosphatidylethanolamine revealed that both types of peptides interacted with the negatively charged lipid cardiolipin. The nonacylated peptides however induced segregation of cardiolipin into peptide-enriched and peptide-poor lipid domains, while the N-acylated peptides promoted formation of many small heterogeneous domains. Only N-acylated peptides caused additional severe effects on the main phase transition of liposomes composed of pure phosphatidylethanolamine, while both peptide types inhibited the lamellar to hexagonal phase transition. Lipid mixtures of phosphatidylethanolamine and cardiolipin revealed anionic clustering by all peptide types. However additional strong perturbation of the neutral lipids was only seen with the N-acylated peptides. Nuclear magnetic resonance demonstrated different conformational arrangement of the N-acylated peptide in anionic and zwitterionic micelles revealing possible mechanistic differences in their action on different membrane lipids. We hypothesized that both peptides kill bacteria by interacting with bacterial membrane lipids but only N-acylated peptides interact with both charged cardiolipin and zwitterionic phosphatidylethanolamine resulting in remodeling of the natural phospholipid domains in the E. coli membrane that leads to defects in cell division.
authors.affiliation: Institute of Molecular Biosciences, Biophysics Division, University of Graz, Graz, Austria.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Zweytick
authors.affiliation: Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia.
authors.forename: Bostjan
authors.initials: B
authors.lastname: Japelj
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical School-Houston, Houston, Texas, United States of America.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Mileykovskaya
authors.affiliation: Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia.
authors.forename: Mateja
authors.initials: M
authors.lastname: Zorko
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical School-Houston, Houston, Texas, United States of America.
authors.forename: William
authors.initials: W
authors.lastname: Dowhan
authors.affiliation: Department of Biochemistry, Torrey Pines Institute for Molecular Studies, San Diego, California, United States of America.
authors.forename: Sylvie E
authors.initials: SE
authors.lastname: Blondelle
authors.affiliation: Institute of Molecular Biosciences, Biophysics Division, University of Graz, Graz, Austria.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Riedl
authors.affiliation: Department of Biotechnology, National Institute of Chemistry, Ljubljana, Slovenia; Centre of Excellence EN-FIST, Ljubljana, Slovenia.
authors.forename: Roman
authors.initials: R
authors.lastname: Jerala
authors.affiliation: Institute of Molecular Biosciences, Biophysics Division, University of Graz, Graz, Austria.
authors.forename: Karl
authors.initials: K
authors.lastname: Lohner
mesh_terms: D000215:Acylation; D002152:Calorimetry, Differential Scanning; D066241:Carbon-13 Magnetic Resonance Spectroscopy; D002308:Cardiolipins / Q000378:metabolism*; D002455:Cell Division; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D007781:Lactoferrin / Q000737:chemistry*; D008823:Micelles; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D010446:Peptide Fragments / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D066244:Proton Magnetic Resonance Spectroscopy
chemical_list: D002308:Cardiolipins; D008823:Micelles; D010446:Peptide Fragments; D010714:Phosphatidylethanolamines; D007781:Lactoferrin