X-ray diffraction characterization of the dense phases formed by nucleosome core particles.
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 10(5) to 2.35 x 10(6) 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 10(5) Pa, the calculated NCPs concentration ranges from approximately 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.
Mangenot
Stéphanie
S
Laboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay Cédex, France.
Leforestier
Amélie
A
Durand
Dominique
D
Livolant
Françoise
F
D003460:Crystallization / Q000379:methods*; D006657:Histones / Q000737:chemistry; D046911:Macromolecular Substances; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000737:chemistry*; D011312:Pressure; D011487:Protein Conformation; D012965:Sodium Chloride / Q000737:chemistry*; D014961:X-Ray Diffraction
D006657:Histones; D046911:Macromolecular Substances; D009707:Nucleosomes; D012965:Sodium Chloride