title: Exploring the structure and stability of cholesterol dimer formation in multicomponent lipid bilayers.
abstract: For 40 years, the existence and possible functional importance of cholesterol dimer formation has been discussed. Due to challenges associated with structural studies of membrane lipids, there has as yet been no direct experimental verification of the existence and relevance of the cholesterol dimer. Building on recent advances in lipid force fields for molecular simulation, in this work the structure and stability of the cholesterol dimer is characterized in POPC bilayers in absence and presence of sphingomyelin. The cholesterol dimer structural ensemble is found to consist of sub-states that reflect, but also differ from, previously proposed dimer structures. While face-to-face dimer structures predominate, no evidence is found for the existence of tail-to-tail dimers in POPC lipid bilayers. Near stoichiometric complex formation of cholesterol with sphingomyelin is found to effect cholesterol dimer structure without impacting population. Comparison with NMR-derived order parameters provide validation for the simulation model employed and conclusions drawn related to the structure and stability of cholesterol dimers in multicomponent lipid bilayers. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Chemistry, Boston University, 590 Commonwealth Ave, Boston, Massachusetts, 02215.
authors.forename: Asanga
authors.identifier: 0000-0003-1264-7330
authors.initials: A
authors.lastname: Bandara
authors.affiliation: Department of Chemistry, Boston University, 590 Commonwealth Ave, Boston, Massachusetts, 02215.
authors.forename: Afra
authors.initials: A
authors.lastname: Panahi
authors.affiliation: Department of Chemistry, Boston University, 590 Commonwealth Ave, Boston, Massachusetts, 02215.
authors.forename: George A
authors.initials: GA
authors.lastname: Pantelopulos
authors.affiliation: Department of Chemistry, Boston University, 590 Commonwealth Ave, Boston, Massachusetts, 02215.
authors.forename: John E
authors.initials: JE
authors.lastname: Straub
mesh_terms: D002784:Cholesterol / Q000737:chemistry*; D019281:Dimerization; D008051:Lipid Bilayers / Q000737:chemistry*; D008962:Models, Theoretical; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D013109:Sphingomyelins / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D013109:Sphingomyelins; D002784:Cholesterol
keywords: cholesterol; cholesterol dimer; lipid aggregation; lipid bilayers; membrane domain formation; sphingomyelin