title: Nonadditive Compositional Curvature Energetics of Lipid Bilayers.
abstract: The unique properties of the individual lipids that compose biological membranes together determine the energetics of the surface. The energetics of the surface, in turn, govern the formation of membrane structures and membrane reshaping processes, and thus they will underlie cellular-scale models of viral fusion, vesicle-dependent transport, and lateral organization relevant to signaling. The spontaneous curvature, to the best of our knowledge, is always assumed to be additive. We describe observations from simulations of unexpected nonadditive compositional curvature energetics of two lipids essential to the plasma membrane: sphingomyelin and cholesterol. A model is developed that connects molecular interactions to curvature stress, and which explains the role of local composition. Cholesterol is shown to lower the number of effective Kuhn segments of saturated acyl chains, reducing lateral pressure below the neutral surface of bending and favoring positive curvature. The effect is not observed for unsaturated (flexible) acyl chains. Likewise, hydrogen bonding between sphingomyelin lipids leads to positive curvature, but only at sufficient concentration, below which the lipid prefers negative curvature.
authors.affiliation: National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, 20892 Maryland, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Sodt
authors.affiliation: National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, 20892 Maryland, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Venable
authors.affiliation: Department of Physics and Astronomy and Department of Chemistry and Biochemistry, University of Delaware, Newark, 19716 Delaware, USA.
authors.forename: E
authors.initials: E
authors.lastname: Lyman
authors.affiliation: National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, 20892 Maryland, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Pastor
mesh_terms: D002462:Cell Membrane / Q000737:chemistry*; D002784:Cholesterol / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008563:Membrane Lipids / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D013109:Sphingomyelins / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D008563:Membrane Lipids; D013109:Sphingomyelins; D002784:Cholesterol