title: Coupling between pore formation and phase separation in charged lipid membranes.
abstract: We investigated the effect of charge on the membrane morphology of giant unilamellar vesicles (GUVs) composed of various mixtures containing charged lipids. We observed the membrane morphologies by fluorescent and confocal laser microscopy in lipid mixtures consisting of a neutral unsaturated lipid [dioleoylphosphatidylcholine (DOPC)], a neutral saturated lipid [dipalmitoylphosphatidylcholine (DPPC)], a charged unsaturated lipid [dioleoylphosphatidylglycerol (DOPG((-)))], a charged saturated lipid [dipalmitoylphosphatidylglycerol (DPPG((-)))], and cholesterol (Chol). In binary mixtures of neutral DOPC-DPPC and charged DOPC-DPPG((-))), spherical vesicles were formed. On the other hand, pore formation was often observed with GUVs consisting of DOPG((-))) and DPPC. In a DPPC-DPPG((-)))-Chol ternary mixture, pore-formed vesicles were also frequently observed. The percentage of pore-formed vesicles increased with the DPPG((-))) concentration. Moreover, when the head group charges of charged lipids were screened by the addition of salt, pore-formed vesicles were suppressed in both the binary and ternary charged lipid mixtures. We discuss the mechanisms of pore formation in charged lipid mixtures and the relationship between phase separation and the membrane morphology. Finally, we reproduce the results seen in experimental systems by using coarse-grained molecular dynamics simulations.
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.|Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu 761-0395, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Himeno
authors.affiliation: Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ito
authors.affiliation: Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Higuchi
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hamada
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
authors.forename: Naofumi
authors.initials: N
authors.lastname: Shimokawa
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takagi
mesh_terms: D002462:Cell Membrane / Q000737:chemistry*; D008563:Membrane Lipids / Q000737:chemistry; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D016062:Porosity; D013696:Temperature; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D008563:Membrane Lipids; D053835:Unilamellar Liposomes