DNA binding to zwitterionic model membranes

M L Ainalem, N Kristen, Karen Edler, F Hook, E Sparr, T Nylander

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)

Abstract

This study shows that DNA (linearized plasmid, 4331 base pairs and salmon sperm, 2000 base pairs, respectively) adsorbs to model membranes of zwitterionic liquid crystalline phospholipid bilayers in solutions containing divalent Ca2+ rations, and also in solutions containing monovalent Na+. The interaction between DNA and surface-supported model membranes was followed in situ using null ellipsometry, quartz crystal microbalance with dissipation, as well as neutron reflectometry. In the presence of Na+ (in the absence Of multivalent ions), DNA adopts an extended coil conformation upon adsorption. The solvent content in the adsorbed layer is high, and DNA is positioned on top of the membrane. In the presence of divalent Ca2+. the driving force for the adsorption of DNA is electrostatic, and the adsorbed DNA film is not as dilute its in a solution containing Na+. Cryo-TEM and SANS were further used to investigate the interaction in bulk solution using vesicles as model membrane systems. DNA adsorption could not be identified in the presence of Na+ using SANS, but cryo-TEM indicates the presence of DNA between neighboring unilamellar vesicles. In the presence of Ca2+. DNA induces the formation of multilamellar vesicles in which DNA intercalates the lamellae. Possible electrostatic and hydrophobic mechanisms for the adsorption of DNA in solutions containing monovalent salt are discussed and compared to the observations in divalent salt.
Original languageEnglish
Pages (from-to)4965-4976
Number of pages12
JournalLangmuir
Volume26
Issue number7
DOIs
Publication statusPublished - 6 Apr 2010

Keywords

  • quartz crystal microbalance with dissipation
  • zwitterionic liquids
  • cryo-TEM
  • hydrophobic mechanisms
  • model membranes
  • base pairs
  • multivalent ions
  • monovalent salt
  • DNA films
  • null ellipsometry
  • adsorbed layers
  • DNA binding
  • multi-lamellar vesicles
  • bulk solutions
  • phospholipid bilayer
  • model membrane systems
  • in-situ
  • driving forces
  • neutron reflectometry
  • unilamellar vesicle
  • solvent content
  • coil conformations

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