title: The plasticins: membrane adsorption, lipid disorders, and biological activity.
abstract: The present study investigates the relationships between structural polymorphism, adsorption onto membrane mimetic support, lipid disturbance, and biological activity of bactericidal 23-residue, glycine-leucine-rich dermaseptin orthologues from the Phyllomedusinae frog skin, the "plasticins". Biological activities were evaluated using the membrane models DMPG (1,2-dimyristoyl-sn-glycero-3-phosphatidylglycerol) for prokaryotic membranes and DMPC (1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine) for eukaryotic membranes. We performed a conformational analysis of plasticins by molecular simulations and spectroscopic methods and analyzed phospholipid perturbations by infrared spectroscopy. Adsorption onto synthetic model membranes was quantified by surface plasmon resonance. Biological assays including antimicrobial and membrane potential-dissipating activities, together with hemolytic tests and imaging analysis of cytotoxicity, were carried out to clarify the peptide-membrane interactions. Two major groups were distinguished: (i) Neutral plasticins revealed the presence of strong beta-structures with the zwitterionic or anionic phospholipid vesicles. They were weakly adsorbed in the range of antibacterial activity concentrations (micromolar). Nevertheless, for millimolar concentrations, they caused perturbations at the interface peptide-DMPG vesicles and in the bilayer alkyl chains, suggesting insertion into bacterial membranes. (ii) Cationic plasticins revealed multiple conformational transitions, including destabilized helix states, beta-structures, and disordered states. Peptide-lipid complex densities depended on hydrophobic bond strengths. The most soluble cationic plasticins were strongly adsorbed, with stable peptide-lipid interactions inducing noticeable perturbations of bilayer alkyl chains, pointing out possible insertion into bacterial membranes. In contrast, cytotoxic plasticins were less adsorbed, with less stable peptide-lipid interactions causing membrane dehydration, formation of peptide-membrane hydrogen bonds, and little disturbances of lipid alkyl chains. These characteristics could be compatible with their putative action on intracellular targets leading to apoptosis.
authors.affiliation: Peptidome de la Peau d'Amphibiens, FRE 2852, CNRS, Université Pierre et Marie Curie (Paris-6), Tour 43, 2 Place Jussieu, 75251 Paris Cedex 05, France. elamri@ccr.jussieu.fr
authors.forename: Chahrazade
authors.initials: C
authors.lastname: El Amri
authors.forename: Claire
authors.initials: C
authors.lastname: Lacombe
authors.forename: Karel
authors.initials: K
authors.lastname: Zimmerman
authors.forename: Ali
authors.initials: A
authors.lastname: Ladram
authors.forename: Mohamed
authors.initials: M
authors.lastname: Amiche
authors.forename: Pierre
authors.initials: P
authors.lastname: Nicolas
authors.forename: Francine
authors.initials: F
authors.lastname: Bruston
mesh_terms: D000327:Adsorption; D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D002942:Circular Dichroism; D003198:Computer Simulation; D004926:Escherichia coli / Q000187:drug effects; D005136:Eye Proteins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D006367:HeLa Cells; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008055:Lipids / Q000737:chemistry*; D008564:Membrane Potentials; D008567:Membranes, Artificial; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D020349:Surface Plasmon Resonance
chemical_list: D000900:Anti-Bacterial Agents; D005136:Eye Proteins; D008055:Lipids; D008567:Membranes, Artificial; D009419:Nerve Tissue Proteins; D012996:Solutions; C076104:plasticin