title: Molecular Insight into the Line Tension of Bilayer Membranes Containing Hybrid Polyunsaturated Lipids.
abstract: Line tension (γ) is a key parameter for the structure and dynamics of membrane domains. It was proposed that hybrid lipids, with mixed saturated and unsaturated acyl chains, participate in the relaxation of γ through different mechanisms. In this work, we used molecular dynamics simulations of the coarse-grained MARTINI model to measure γ in liquid-ordered-liquid-disordered (Lo-Ld) membranes, with increasingly larger relative proportion of the hybrid polyunsaturated lipid PAPC (4:0-5:4PC) to DAPC (di5:4PC) (i.e., XH). We also calculated an elastic contribution to γ by the Lo-Ld thickness mismatch, tilt moduli, and bending moduli, as predicted by theory. We found that an increase in XHdecreased the overall γ value and the elastic contribution to line tension. The effect on the elastic line tension is driven by a reduced hydrophobic mismatch. Changes in the elastic constants of the phases due to an increase in XHproduced a slightly larger elastic γ term. In addition to this elastic energy, other major contributions to γ are found in these model membranes. Increasing XHdecreases both elastic and nonelastic contributions to γ. Finally, PAPC also behaves as a linactant, relaxing γ through an interfacial effect, as predicted by theoretical results. This study gives insight into the actual contribution of distinct energy terms to γ in bilayers containing polyunsaturated hybrid lipids.
authors.affiliation: Centro de Química Biológica de Córdoba, CIQUIBIC, Departamento de Química Biológica, Facultad de Ciencias Químicas, CONICET, Universidad Nacional de Córdoba, Ciudad Universitaria , X5000HUA, Córdoba, Argentina.
authors.forename: Carla M
authors.identifier: 0000-0002-0733-2935
authors.initials: CM
authors.lastname: Rosetti
authors.affiliation: Centro de Química Biológica de Córdoba, CIQUIBIC, Departamento de Química Biológica, Facultad de Ciencias Químicas, CONICET, Universidad Nacional de Córdoba, Ciudad Universitaria , X5000HUA, Córdoba, Argentina.
authors.forename: Guillermo G
authors.initials: GG
authors.lastname: Montich
authors.affiliation: Departamento de Física, Centro Atómico Constituyentes CNEA , Av. Gral. Paz 1499, 1650 San Martín, Buenos Aires, Argentina.|CONICET , Avda. Rivadavia 1917, C1033AAJ Cdad. de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Claudio
authors.initials: C
authors.lastname: Pastorino
mesh_terms: D002784:Cholesterol / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D021962:Membrane Microdomains / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D010713:Phosphatidylcholines / Q000737:chemistry*; D013696:Temperature
chemical_list: C468114:1-palmitoyl-2-arachidonyl-3-phosphorylcholine; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; C044819:1,2-diarachidonoyl-glycero-3-phosphocholine; D002784:Cholesterol