Structural analysis of DNA complexation with cationic lipids

Nucleic Acids Res. 2009 Feb;37(3):849-57. doi: 10.1093/nar/gkn1003. Epub 2008 Dec 22.

Abstract

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 K(Chol) = 1.4 (+/-0.5) x 10(4) M(-1), K(DDAB) = 2.4 (+/-0.80) x 10(4) M(-1), K(DOTAP) = 3.1 (+/-0.90) x 10(4) M(-1) and K(DOPE) = 1.45 (+/- 0.60) x 10(4) 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cations / chemistry
  • Cholesterol / chemistry
  • Circular Dichroism
  • DNA / chemistry*
  • DNA / ultrastructure
  • Fatty Acids, Monounsaturated / chemistry
  • Hydrophobic and Hydrophilic Interactions
  • Lipids / chemistry*
  • Microscopy, Atomic Force
  • Nucleic Acid Conformation
  • Phosphates / chemistry
  • Phosphatidylethanolamines / chemistry
  • Quaternary Ammonium Compounds / chemistry
  • Spectroscopy, Fourier Transform Infrared

Substances

  • Cations
  • Fatty Acids, Monounsaturated
  • Lipids
  • Phosphates
  • Phosphatidylethanolamines
  • Quaternary Ammonium Compounds
  • didodecyldimethylammonium
  • dioleoyl phosphatidylethanolamine
  • DNA
  • calf thymus DNA
  • Cholesterol
  • 1,2-dioleoyloxy-3-(trimethylammonium)propane