This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mangenot, S. Articles by Livolant, F. Search for Related Content PubMed PubMed Citation Articles by Mangenot, S. Articles by Livolant, F.

X-Ray Diffraction Characterization of the Dense Phases Formed by Nucleosome Core Particles

Stéphanie Mangenot, Amélie Leforestier, Dominique Durand and Françoise Livolant

Laboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay Cédex, France; and Laboratoire LURE, Université Paris-Sud, 91898 Orsay Cédex, France

Correspondence: Address reprint requests to Dominique Durand, E-mail: durand{at}lure.u-psud.fr.

Multiple dense phases of nucleosome core particles (NCPs) were formed in controlled ionic conditions (15–160 mM monovalent salt, no divalent ions), under osmotic pressures ranging from 4.7 x 10⁵ to 2.35 x 10⁶ Pa. We present here the x-ray diffraction analysis of these phases. In the lamello-columnar phase obtained at low salt concentration (<25 mM), NCPs stack into columns that align to form bilayers, kept separated from one another by a layer of solvent. NCPs form a monoclinic lattice in the plane of the bilayer. For high salt concentration (>50 mM), NCPs order into either a two-dimensional columnar hexagonal phase or into three-dimensional orthorhombic (quasi-hexagonal) crystals. The lamellar and hexagonal (or quasi-hexagonal) organizations coexist in the intermediate salt range; their demixing requires a long time. For an applied pressure P = 4.7 10⁵ Pa, the calculated NCPs concentration ranges from 280 to 320 mg/ml in the lamello-columnar phase to 495 to 585 mg/ml in the three-dimensional orthorhombic phase. These concentrations cover the concentration of the living cell.