title: Dye-release assay for investigation of antimicrobial peptide activity in a competitive lipid environment.
abstract: A dye-release method for investigating the effect of a competitive lipid environment on the activity of two membrane-disrupting antimicrobial peptides (AMP), maculatin 1.1 and aurein 1.2, is presented. The results support the general conclusion that AMP have greater affinity for negatively charged membranes, for example bacterial membranes, than for the neutral membrane surface found in eukaryotic cells, but only within a competitive lipid environment. Indeed, in a single-model membrane environment, both peptides were more potent against neutral vesicles than against charged vesicles. The approach was also used to investigate the effect of pre-incubating the peptides in a neutral lipid environment then introducing charged lipid vesicles. Maculatin was shown to migrate from the neutral lipid bilayers, where pores had already formed, to the charged membrane bilayers. This result was also observed for charged-to-charged bilayers but, interestingly, not for neutral-to-neutral lipid interfaces. Aurein was able to migrate from either lipid environment, indicating weaker binding to lipid membranes, and a different molecular mechanism for lysis of lipid bilayers. Competitive lipid environments could be used to assess other critical conditions that modulate the activity of membrane peptides or proteins.
authors.affiliation: School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC, 3010, Australia, msani@unimelb.edu.au.
authors.forename: Marc-Antoine
authors.initials: MA
authors.lastname: Sani
authors.forename: Eve
authors.initials: E
authors.lastname: Gagne
authors.forename: John D
authors.initials: JD
authors.lastname: Gehman
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Whitwell
authors.forename: Frances
authors.initials: F
authors.lastname: Separovic
mesh_terms: D000595:Amino Acid Sequence; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000378:metabolism*; D001667:Binding, Competitive; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D004396:Coloring Agents / Q000737:chemistry*; D008563:Membrane Lipids / Q000378:metabolism*; D008969:Molecular Sequence Data
chemical_list: D023181:Antimicrobial Cationic Peptides; D004396:Coloring Agents; D008563:Membrane Lipids