title: Structure and mechanism of action of a de novo antimicrobial detergent-like peptide.
abstract: The K4 peptide (KKKKPLFGLFFGLF) was recently demonstrated to display good antimicrobial activities against various bacterial strains and thus represents a candidate for the treatment of multiple-drug resistant infections. In this study, we use various techniques to study K4 behaviour in different media: water, solutions of detergent micelles, phospholipid monolayers and suspension of phospholipid vesicles. First, self-assembly of the peptide in water is observed, leading to the formation of spherical objects around 10nm in diameter. The addition of micelles induces partial peptide folding to an extent depending on the charge of the detergent headgroups. The NMR structure of the peptide in the presence of SDS displays a helical character of the hydrophobic moiety, whereas only partial folding is observed in DPC micelles. This peptide is able to destabilize the organization of monolayer membranes or bilayer liposomes composed of anionic lipids. When added on small unilamellar vesicles it generates larger objects attributed to mixed lipid-peptide vesicles and aggregated vesicles. The absence of calcein leakage from liposomes, when adding K4, underlines the original mechanism of this linear amphipathic peptide. Our results emphasize the importance of the electrostatic effect for K4 folding and lipid destabilization leading to the microorganisms' death with a high selectivity for the eukaryotic cells at the MIC. Interestingly, the micrographs obtained by electronic microscopy after addition of peptide on bacteria are also consistent with the formation of mixed lipid-peptide objects. Overall, this work supports a detergent-like mechanism for the antimicrobial activity of this peptide.
authors.affiliation: RMN-ILP, UMR CNRS 6026, PRISM, Université de Rennes 1, CS 34317, Campus de Villejean, 35043 Rennes Cedex, France.
authors.forename: Baptiste
authors.initials: B
authors.lastname: Legrand
authors.forename: Mathieu
authors.initials: M
authors.lastname: Laurencin
authors.forename: Joe
authors.initials: J
authors.lastname: Sarkis
authors.forename: Emilie
authors.initials: E
authors.lastname: Duval
authors.forename: Liza
authors.initials: L
authors.lastname: Mouret
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Hubert
authors.forename: Murielle
authors.initials: M
authors.lastname: Collen
authors.forename: Véronique
authors.initials: V
authors.lastname: Vié
authors.forename: Céline
authors.initials: C
authors.lastname: Zatylny-Gaudin
authors.forename: Joël
authors.initials: J
authors.lastname: Henry
authors.forename: Michèle
authors.initials: M
authors.lastname: Baudy-Floc'h
authors.forename: Arnaud
authors.initials: A
authors.lastname: Bondon
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry*; D002942:Circular Dichroism; D003902:Detergents / Q000737:chemistry*; D005452:Fluoresceins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D018625:Microscopy, Atomic Force / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008958:Models, Molecular; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D011522:Protons; D014867:Water / Q000737:chemistry
chemical_list: D000890:Anti-Infective Agents; D003902:Detergents; D005452:Fluoresceins; D008055:Lipids; D010455:Peptides; D011522:Protons; D014867:Water; C007740:fluorexon