title: Structure and internal organization of overcharged cationic-lipid/peptide/DNA self-assembly complexes.
abstract: The combination of cationic lipids with cationic peptides and DNA vectors can produce synergistic effects in gene delivery to eukaryotic cells. Binary complexes of cationic lipids with DNA are well-studied whereas little information is available about the structure of the ternary lipid/peptide/DNA (LPD) complexes and mechanisms defining DNA protection and delivery. Here we use synchrotron small angle X-ray scattering and dynamic light scattering zeta-potential measurements to determine structure and the net charge of supramolecular aggregates of complexes in mixtures of plasmid DNA, cationic liposomes formed from DOTAP, plus a linear cationic epsilon-oligolysine with the pendant alpha-amino acids Leu-Tyr-Arg (LYR), epsilon-(LYR)K10. These ternary complexes display multilamellar structures with relatively constant separation between DOTAP bilayers, accommodating a hydrated monolayer of parallel DNA rods. The DNA-DNA distance in the complexes varies as a function of the net positive to negative (lipid + peptide)/DNA charge ratio. An explanation for the observed dependence of DNA-DNA distance on charge ratio was proposed based on general polyelectrolyte properties of non-stoichiometric polycation-DNA mixtures.
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
authors.forename: Jiang
authors.initials: J
authors.lastname: Yan
authors.forename: Nikolay V
authors.initials: NV
authors.lastname: Berezhnoy
authors.forename: Nikolay
authors.initials: N
authors.lastname: Korolev
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Su
authors.forename: Lars
authors.initials: L
authors.lastname: Nordenskiöld
mesh_terms: D000595:Amino Acid Sequence; D002412:Cations / Q000737:chemistry; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004553:Electric Conductivity; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D005822:Genetic Vectors / Q000737:chemistry / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics; D008055:Lipids / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010957:Plasmids / Q000737:chemistry / Q000235:genetics; D011107:Polylysine / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D053838:Scattering, Small Angle; D017356:Synchrotrons; D014162:Transfection / Q000379:methods; D014961:X-Ray Diffraction
chemical_list: C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D002412:Cations; D005229:Fatty Acids, Monounsaturated; D005456:Fluorescent Dyes; D008055:Lipids; D046911:Macromolecular Substances; D010455:Peptides; D010714:Phosphatidylethanolamines; D000644:Quaternary Ammonium Compounds; D049452:Green Fluorescent Proteins; D011107:Polylysine; D004247:DNA; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane