title: Structure of DNA-cationic liposome complexes: DNA intercalation in multilamellar membranes in distinct interhelical packing regimes.
abstract: Cationic liposomes complexed with DNA (CL-DNA) are promising synthetically based nonviral carriers of DNA vectors for gene therapy. The solution structure of CL-DNA complexes was probed on length scales from subnanometer to micrometer by synchrotron x-ray diffraction and optical microscopy. The addition of either linear lambda-phage or plasmid DNA to CLs resulted in an unexpected topological transition from liposomes to optically birefringent liquid-crystalline condensed globules. X-ray diffraction of the globules revealed a novel multilamellar structure with alternating lipid bilayer and DNA monolayers. The lambda-DNA chains form a one-dimensional lattice with distinct interhelical packing regimes. Remarkably, in the isoelectric point regime, the lambda-DNA interaxial spacing expands between 24.5 and 57.1 angstroms upon lipid dilution and is indicative of a long-range electrostatic-induced repulsion that is possibly enhanced by chain undulations.
authors.affiliation: Materials Department, University of California, Santa Barbara, CA 93106, USA.
authors.forename: J O
authors.initials: JO
authors.lastname: Rädler
authors.forename: I
authors.initials: I
authors.lastname: Koltover
authors.forename: T
authors.initials: T
authors.lastname: Salditt
authors.forename: C R
authors.initials: CR
authors.lastname: Safinya
mesh_terms: D010582:Bacteriophage lambda; D002412:Cations; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004247:DNA / Q000737:chemistry*; D004279:DNA, Viral / Q000737:chemistry*; D005229:Fatty Acids, Monounsaturated; D007526:Isoelectric Point; D008027:Light; D008051:Lipid Bilayers; D008081:Liposomes; D008856:Microscopy, Fluorescence; D008857:Microscopy, Interference; D009690:Nucleic Acid Conformation; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010957:Plasmids; D000644:Quaternary Ammonium Compounds; D012542:Scattering, Radiation; D014961:X-Ray Diffraction
chemical_list: D002412:Cations; D004279:DNA, Viral; D005229:Fatty Acids, Monounsaturated; D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D000644:Quaternary Ammonium Compounds; C020888:1,2-dielaidoylphosphatidylethanolamine; D004247:DNA; C017251:1,2-oleoylphosphatidylcholine; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane