Direct visualization of membrane leakage induced by the antibiotic peptides: Maculatin, citropin, and aurein

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dc.contributor.authorAmbroggio, E.
dc.contributor.authorSeparovic, F.
dc.contributor.authorBowie, J.
dc.contributor.authorFidelio, G.
dc.contributor.authorBagatolli, L.
dc.date.issued2005
dc.descriptionCopyright © 2005 The Biophysical Society The document attached has been archived with permission from the publisher.
dc.description.abstractMembrane lysis caused by antibiotic peptides is often rationalized by means of two different models: the so-called carpet model and the pore-forming model. We report here on the lytic activity of antibiotic peptides from Australian tree frogs, Maculatin 1.1, Citropin 1.1, and Aurein 1.2, on POPC or POPC/POPG model membranes. Leakage experiments using fluorescence spectroscopy indicated that the peptide/lipid mol ratio necessary to induce 50% of probe leakage was smaller for Maculatin compared with Aurein or Citropin, regardless of lipid membrane composition. To gain further insight into the lytic mechanism of these peptides we performed single vesicle experiments using confocal fluorescence microscopy. In these experiments, the time course of leakage for different molecular weight (water soluble) fluorescent markers incorporated inside of single giant unilamellar vesicles is observed after peptide exposure. We conclude that Maculatin and its related peptides demonstrate a pore-forming mechanism (differential leakage of small fluorescent probe compared with high molecular weight markers). Conversely, Citropin and Aurein provoke a total membrane destabilization with vesicle burst without sequential probe leakage, an effect that can be assigned to a carpeting mechanism of lytic action. Additionally, to study the relevance of the proline residue on the membrane-action properties of Maculatin, the same experimental approach was used for Maculatin-Ala and Maculatin-Gly (Pro-15 was replaced by Ala or Gly, respectively). Although a similar peptide/lipid mol ratio was necessary to induce 50% of leakage for POPC membranes, the lytic activity of Maculatin-Ala and Maculatin-Gly decreased in POPC/POPG (1:1 mol) membranes compared with that observed for the naturally occurring Maculatin sequence. As observed for Maculatin, the lytic action of Maculatin-Ala and Maculatin-Gly is in keeping with the formation of pore-like structures at the membrane independently of lipid composition.
dc.description.statementofresponsibilityErnesto E. Ambroggio, Frances Separovic, John H. Bowie, Gerardo D. Fidelio and Luis A. Bagatolli
dc.identifier.citationBiophysical Journal, 2005; 89(3):1874-1881
dc.identifier.doi10.1529/biophysj.105.066589
dc.identifier.issn0006-3495
dc.identifier.issn1542-0086
dc.identifier.urihttp://hdl.handle.net/2440/17885
dc.language.isoen
dc.publisherBiophysical Society
dc.source.urihttp://www.biophysj.org/cgi/reprint/89/3/1874
dc.subjectMembranes
dc.subjectCell Membrane
dc.subjectAnimals
dc.subjectRanidae
dc.subjectFluoresceins
dc.subjectLipids
dc.subjectMembrane Lipids
dc.subjectLipid Bilayers
dc.subjectPhosphatidylcholines
dc.subjectPhosphatidylglycerols
dc.subjectPeptides
dc.subjectAntimicrobial Cationic Peptides
dc.subjectAmphibian Proteins
dc.subjectAnti-Bacterial Agents
dc.subjectMicroscopy, Confocal
dc.subjectMicroscopy, Fluorescence
dc.subjectMutagenesis
dc.subjectTime Factors
dc.titleDirect visualization of membrane leakage induced by the antibiotic peptides: Maculatin, citropin, and aurein
dc.typeJournal article
pubs.publication-statusPublished

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