Supramolecular Organization in Self-Assembly of Chromatin and Cationic Lipid Bilayers is Controlled by Membrane Charge Density

Research output: Contribution to journalArticle

Abstract

In this work we have investigated the structures of aggregates formed in model systems of dilute aqueous mixtures of "model chromatin" consisting of either recombinant nucleosome core particles (NCPs) or nucleosome arrays consisting of 12 NCPs connected with 30 bp linker DNA, and liposomes made from different mixtures of cationic and zwitterionic lipids, 1,2-dioleoyl-3-trimethylammonium-propane chloride salt (DOTAP) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). The aggregates formed were characterized using different optical microscopy methods and small-angle X-ray scattering (SAXS), and the results are discussed in terms of the competing intermolecular interactions among the components. For a majority of the samples, the presence of lamellar structures could be identified. Ir. samples with high fractions of DOTAP in the liposomes, well-defined lamellar structures very similar to those formed by the corresponding lipid mixtures and DNA alone (i.e., without histone proteins) were observed; in these aggregates, the histones are expelled from the model chromatin. The findings suggest that, with liposomes containing large fractions of cationic lipid, the dominating driving force for aggregation is the increase in translational entropy from the release of counterions, whereas with lower fractions of the cationic lipid, the entropy of mixing of the lipids within the bilayers results in a decreased DNA-lipid attraction.

Details

Authors
  • Nikolay V. Berezhnoy
  • Dan Lundberg
  • Nikolay Korolev
  • Chenning Lu
  • Jiang Yan
  • Maria Miguel
  • Björn Lindman
  • Lars Nordenskioeld
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Chemistry
Original languageEnglish
Pages (from-to)4146-4157
JournalBiomacromolecules
Volume13
Issue number12
Publication statusPublished - 2012
Publication categoryResearch
Peer-reviewedYes