title: Interaction of a two-transmembrane-helix peptide with lipid bilayers and dodecyl sulfate micelles.
abstract: To probe structural changes that occur when a membrane protein is transferred from lipid bilayers to SDS micelles, a fragment of bacteriorhodopsin containing transmembrane helical segments A and B was studied by fluorescence spectroscopy, molecular dynamics (MD) simulation, and stopped flow kinetics. In lipid bilayers, Förster resonance energy transfer (FRET) was observed between tyrosine 57 on helix B and tryptophans 10 and 12 on helix A. FRET efficiency decreased substantially when the peptide was transferred to SDS. MD simulation showed no evidence for significant disruption of helix-helix interactions in SDS micelles. However, a cluster of water molecules was observed to form a hydrogen-bonded network with the phenolic hydroxyl group of tyrosine 57, which probably causes the disappearance of tyrosine-to-tryptophan FRET in SDS. The tryptophan quantum yield decreased in SDS, and the change occurred at nearly the same rate as membrane solubilization. The results provide a clear example of the importance of corroborating distance changes inferred from FRET by using complementary methods.
authors.affiliation: Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA. Robert.Renthal@UTSA.edu
authors.forename: Robert
authors.initials: R
authors.lastname: Renthal
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Brancaleon
authors.forename: Isaac
authors.initials: I
authors.lastname: Peña
authors.forename: Frances
authors.initials: F
authors.lastname: Silva
authors.forename: Liao Y
authors.initials: LY
authors.lastname: Chen
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry*; D001436:Bacteriorhodopsins / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D019617:Halobacterium salinarum / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008823:Micelles; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D019843:Archaeal Proteins; D008051:Lipid Bilayers; D008823:Micelles; D010455:Peptides; D012967:Sodium Dodecyl Sulfate; D001436:Bacteriorhodopsins; C028913:dodecyl sulfate