title: Oligomerization of daptomycin on membranes.
abstract: Daptomycin is a lipopeptide antibiotic that kills Gram-positive bacteria by membrane depolarization. While it has long been assumed that the mode of action of daptomycin involves the formation of membrane-associated oligomers, this has so far not been experimentally demonstrated. We here use FRET between native daptomycin and an NBD-labeled daptomycin derivative to show that such oligomerization indeed occurs. The oligomers are observed in the presence of calcium ions on membrane vesicles isolated from Bacillus subtilis, as well as on model membranes containing the negatively charged phospholipid phosphatidylglycerol. In contrast, oligomerization does not occur on membranes containing phosphatidylcholine only, nor in solution at micromolar daptomycin concentrations. The requirements for oligomerization of daptomycin resemble those previously reported for antibacterial activity, suggesting that oligomerization is necessary for the activity.
authors.affiliation: Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Jawad K
authors.initials: JK
authors.lastname: Muraih
authors.forename: Andre
authors.initials: A
authors.lastname: Pearson
authors.forename: Jared
authors.initials: J
authors.lastname: Silverman
authors.forename: Michael
authors.initials: M
authors.lastname: Palmer
mesh_terms: D009327:4-Chloro-7-nitrobenzofurazan / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects / Q000254:growth & development; D002118:Calcium / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry*; D017576:Daptomycin / Q000737:chemistry* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D031541:Fluorescence Resonance Energy Transfer; D008956:Models, Chemical; D015394:Molecular Structure; D010715:Phosphatidylglycerols / Q000737:chemistry; D055503:Protein Multimerization; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D010715:Phosphatidylglycerols; D053835:Unilamellar Liposomes; D009327:4-Chloro-7-nitrobenzofurazan; D017576:Daptomycin; D002118:Calcium