title: Aggregation and organization of pardaxin in phospholipid membranes. A fluorescence energy transfer study.
abstract: Fluorescence resonance energy transfer has been used to study the aggregation and organization of pardaxin and its analogues within lipid membranes. Peptide molecules labeled with 5- (and 6-) carboxyfluorescein at their N-terminal amino acid served as donors in these energy transfer measurements, whereas peptides labeled with 5- (and 6-) carboxytetramethylrhodamine at either their N- or C-terminal amino acid, served as acceptors. The membrane-permeating activity of the native molecule was maintained in the labeled peptides. Upon aggregation of the labeled peptides, fluorescence energy transfer was detected as a quenching of the donor fluorescence (520 nm), as well as an enhancement of the acceptor fluorescence (575 nm). Correlation exists between self-aggregation of the different analogues within membranes and their poreforming abilities. A comparison of the degrees of fluorescence energy transfer from N1-donor-labeled pardaxin to N1-acceptor-labeled pardaxin with the transfer efficiency observed in the interaction between the same donor and C1-acceptor-labeled pardaxin suggests that aggregates are formed in an ordered manner, with a preferentially parallel orientation of monomers within the aggregate. The extent of hetero-oligomer formation, i.e. complexes composed of two different analogue species, revealed that complementary charges contribute to peptide-peptide recognition within the lipid bilayer. Taken together, these results provide further support for the barrel stave model, involving parallel organization of monomers within the aggregate, as a description of the pore formation mechanism of pardaxin and its analogues.
authors.affiliation: Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: D
authors.initials: D
authors.lastname: Rapaport
authors.forename: Y
authors.initials: Y
authors.lastname: Shai
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D004396:Coloring Agents; D005397:Fish Venoms / Q000737:chemistry*; D005452:Fluoresceins / Q000737:chemistry; D005453:Fluorescence; D008051:Lipid Bilayers; D008081:Liposomes; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry
chemical_list: D004396:Coloring Agents; D005397:Fish Venoms; D005452:Fluoresceins; D008051:Lipid Bilayers; D008081:Liposomes; D010455:Peptides; D010743:Phospholipids; D012235:Rhodamines; C024098:6-carboxyfluorescein; C005358:tetramethylrhodamine; C017603:pardaxin