title: The lateral diffusion of selectively aggregated peptides in giant unilamellar vesicles.
abstract: We have systematically investigated the effect of aggregation of a transmembrane peptide on its diffusion in dimyristoylphosphatidylcholine and in palmitoyloleoylphosphatidylcholine model membranes. The hydrophobic segment of the b subunit from E. coli F(1)F(0)-ATP synthase was modified with a histidine tag at the carbonyl terminus and was aggregated selectively by using a series of multivalent, dendritic chelating agents with nitrilotriacetic acid functional groups. Peptide complexes ranging from monomers to hexamers were formed and studied in giant unilamellar vesicles. The rate of diffusion for the transmembrane peptide complexes were found to depend on the size of the complex. The results agree with predictions from the free area model for monomers and dimers, and the hydrodynamic continuum model for tetramers, pentamers, and hexamers. Comparisons with diffusion of lipids confirm that the diffusion of a transmembrane peptide is enhanced by coupling of density fluctuations between the two monolayers.
authors.affiliation: Department of Chemistry, The University of Western Ontario, London, Canada.
authors.forename: Clarence C
authors.initials: CC
authors.lastname: Lee
authors.forename: Matthew
authors.initials: M
authors.lastname: Revington
authors.forename: Stanley D
authors.initials: SD
authors.lastname: Dunn
authors.forename: Nils O
authors.initials: NO
authors.lastname: Petersen
mesh_terms: D000595:Amino Acid Sequence; D025243:Bacterial Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004058:Diffusion; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D046911:Macromolecular Substances; D008560:Membrane Fluidity; D008565:Membrane Proteins / Q000737:chemistry*; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012680:Sensitivity and Specificity
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes; D046911:Macromolecular Substances; D008565:Membrane Proteins; D010455:Peptides; D021122:Protein Subunits; D011994:Recombinant Proteins; D025243:Bacterial Proton-Translocating ATPases