Eur. Phys. J. E 7, 221-231 (2002)
DOI: 10.1140/epje/i200101151

Interactions between isolated nucleosome core particles: A tail-bridging effect?

S. Mangenot¹, E. Raspaud¹, C. Tribet², L. Belloni³ and F. Livolant<sup>1

1</sup>  Laboratoire de Physique des Solides, UMR 8502, Université Paris-Sud, 91405 Orsay cedex, France
²  Laboratoire de Physico-Chimie Macromoléculaire, CNRS UMR 7615, Université Paris 6, UMR 7615, ESPCI, 10 rue Vauquelin, 75231 Paris cedex 05, France
³  Service de Chimie Moléculaire, CEA/Saclay, 91191 Gif-sur-Yvette, France

raspaud@lps.u-psud.fr

(Received 4 October 2001)

Abstract
Interactions between isolated nucleosome core particles are studied as a function of the monovalent salt concentration by osmometry and by electrophoretic mobility measurements. The data are compared to the measurements performed on the protein-free DNA fragments and also analysed using the conventional theoretical approach. At low salt, an electrostatic screening effect accounts for the variation of the second virial coefficient whereas the simple hard-core contribution becomes predominant at high salt. In the intermediate range, an attraction occurs. In the light of previous results (Mangenot et al. , Biophys. J. 82, 345 (2002)), we show that the flexible basic proteic tails are responsible for this attraction. A tail-bridging effect is discussed.

PACS
82.35.Rs - Polyelectrolytes.
87.14.Gg - DNA, RNA.
87.15.Kg - Molecular interactions; membrane-protein interactions.
87.15.Tt - Electrophoresis.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002