title: Phase behavior and the partitioning of caveolin-1 scaffolding domain peptides in model lipid bilayers.
abstract: The membrane binding and model lipid raft interaction of synthetic peptides derived from the caveolin scaffolding domain (CSD) of the protein caveolin-1 have been investigated. CSD peptides bind preferentially to liquid-disordered domains in model lipid bilayers composed of cholesterol and an equimolar ratio of dioleoylphosphatidylcholine (DOPC) and brain sphingomyelin. Three caveolin-1 peptides were studied: the scaffolding domain (residues 83-101), a water-insoluble construct containing residues 89-101, and a water-soluble construct containing residues 89-101. Confocal and fluorescence microscopy investigation shows that the caveolin-1 peptides bind to the more fluid cholesterol-poor phase. The binding of the water-soluble peptide to lipid bilayers was measured using fluorescence correlation spectroscopy (FCS). We measured molar partition coefficients of 10(4) M(-1) between the soluble peptide and phase-separated lipid bilayers and 10(3) M(-1) between the soluble peptide and bilayers with a single liquid phase. Partial phase diagrams for our phase-separating lipid mixture with added caveolin-1 peptides were measured using fluorescence microscopy. The water-soluble peptide did not change the phase morphology or the miscibility transition in giant unilamellar vesicles (GUVs); however, the water-insoluble and full-length CSD peptides lowered the liquid-liquid melting temperature.
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. mhorton@mit.edu
authors.forename: Margaret R
authors.initials: MR
authors.lastname: Horton
authors.forename: Joachim
authors.initials: J
authors.lastname: Rädler
authors.forename: Alice P
authors.initials: AP
authors.lastname: Gast
mesh_terms: D000327:Adsorption; D001665:Binding Sites; D051242:Caveolin 1 / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008954:Models, Biological; D008958:Models, Molecular; D010316:Particle Size; D010455:Peptides / Q000737:chemistry*; D044367:Phase Transition; D013499:Surface Properties
chemical_list: D051242:Caveolin 1; D008051:Lipid Bilayers; D010455:Peptides