Structural analysis of DNA complexation with cationic lipids

• Published in: Nucleic acids research Vol. 37; no. 3; pp. 849 - 857
• Main Authors: Marty, Regis, N'soukpoé-Kossi, Christophe N, Charbonneau, David, Weinert, Carl Maximilian, Kreplak, Laurent, Tajmir-Riahi, Heidar-Ali
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.02.2009; Oxford Publishing Limited (England)
• Subjects: A-DNA; atomic force microscopy; Cations - chemistry; Chemistry and Synthetic Biology; cholesterol; Cholesterol - chemistry; Circular Dichroism; circular dichroism spectroscopy; Deoxyribonucleic acid; DNA; DNA - chemistry; DNA - ultrastructure; electrostatic interactions; Fatty Acids, Monounsaturated - chemistry; Fourier transform infrared spectroscopy; Fourier transforms; gene therapy; Hydrophobic and Hydrophilic Interactions; hydrophobic bonding; lipid content; Lipids; Lipids - chemistry; Microscopy, Atomic Force; Nucleic Acid Conformation; phosphates; Phosphates - chemistry; Phosphatidylethanolamines - chemistry; Quaternary Ammonium Compounds - chemistry; Spectroscopy, Fourier Transform Infrared; Structural analysis; vaccines
• ISSN: 0305-1048; 1362-4962; 1362-4962
• DOI: 10.1093/nar/gkn1003

Complexes of cationic liposomes with DNA are promising tools to deliver genetic information into cells for gene therapy and vaccines. Electrostatic interaction is thought to be the major force in lipid-DNA interaction, while lipid-base binding and the stability of cationic lipid-DNA complexes have been the subject of more debate in recent years. The aim of this study was to examine the complexation of calf-thymus DNA with cholesterol (Chol), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), dioctadecyldimethylammoniumbromide (DDAB) and dioleoylphosphatidylethanolamine (DOPE), at physiological condition, using constant DNA concentration and various lipid contents. Fourier transform infrared (FTIR), UV-visible, circular dichroism spectroscopic methods and atomic force microscopy were used to analyse lipid-binding site, the binding constant and the effects of lipid interaction on DNA stability and conformation. Structural analysis showed a strong lipid-DNA interaction via major and minor grooves and the backbone phosphate group with overall binding constants of KChol = 1.4 (±0.5) x 10⁴ M⁻¹, KDDAB = 2.4 (±0.80) x 10⁴ M⁻¹, KDOTAP = 3.1 (±0.90) x 10⁴ M⁻¹ and KDOPE = 1.45 (± 0.60) x 10⁴ M⁻¹. The order of stability of lipid-DNA complexation is DOTAP>DDAB>DOPE>Chol. Hydrophobic interactions between lipid aliphatic tails and DNA were observed. Chol and DOPE induced a partial B to A-DNA conformational transition, while a partial B to C-DNA alteration occurred for DDAB and DOTAP at high lipid concentrations. DNA aggregation was observed at high lipid content.