Atomic Force Microscopy Imaging of DNA under Macromolecular Crowding Conditions

David Pastre (1) , Loic Hamon (1) , Alain Mechulam (1) , Isabelle Sorel (1) , Sonia Baconnais (2) , Patrick Curmi (1) , Eric Le Cam (2) , Olivier Piétrement (2)

1 SABNP - Structure et activité des biomolécules normales et pathologiques
2 UMR8126 - Signalisation, noyaux et innovations en cancérologie

Studying the influence of macromolecular crowding at high ionic strengths on assemblies of biomolecules is of particular interest because these are standard intracellular conditions. However, up to now, no techniques offer the possibility of studying the effect of molecular crowding at the single molecule scale and at high resolution. We present a method to observe double-strand DNA under macromolecular crowding conditions on a flat mica surface by atomic force microscope. By using high concentrations of monovalent salt ([NaCl] > 100 mM), we promote DNA adsorption onto NiCl2 pretreated muscovite mica. It therefore allows analysis of DNA conformational changes and DNA compaction induced by polyethylene glycol (PEG), a neutral crowding agent, at physiological concentrations of monovalent salt.

Keywords: Molecules; Genetics; Salts; Adsorption; Cations

Domains: Life Sciences [q-bio]

David Pastre, Loic Hamon, Alain Mechulam, Isabelle Sorel, Sonia Baconnais, et al.. Atomic Force Microscopy Imaging of DNA under Macromolecular Crowding Conditions. Biomacromolecules, 2007, 8 (12), pp.3712-3717. ⟨10.1021/bm700856u⟩. ⟨hal-02295397⟩