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Phase diagram of nucleosome core particles
S Mangenot1, A Leforestier, D Durand
1Laboratoire de Physique des Solides, CNRS UMR 8502, Bât 510, Université Paris-Sud, 91405 Orsay Cedex, France.
Journal of Molecular Biology
|October 30, 2003
Summary
Nucleosome core particles (NCPs) form diverse structures like columns and hexagonal phases under varying salt and pressure. These self-assembly behaviors are driven by NCP surface charges and may influence cellular chromatin organization.
Area of Science:
- Biophysics
- Structural Biology
- Materials Science
Background:
- Nucleosome core particles (NCPs) are fundamental units of chromatin.
- Understanding NCPs' supramolecular organization is crucial for comprehending cellular processes.
Purpose of the Study:
- To map the phase diagram of nucleosome core particles (NCPs).
- To investigate the influence of salt concentration and osmotic pressure on NCP self-assembly.
- To explore the relationship between NCP organization and potential cellular functions.
Main Methods:
- Systematic variation of monovalent salt concentration and applied osmotic pressure.
- Observation and characterization of NCP phase behavior.
- Analysis of NCP surface charge distribution and its impact on interactions.
Main Results:
- NCPs form columns above a critical pressure, organizing into isotropic, nematic, lamello-columnar, inverse hexagonal, 2D hexagonal, or 3D orthorhombic phases.
- Microphase separation occurs at intermediate salt concentrations.
- NCP phase behavior is highly sensitive to ionic environment due to heterogeneous surface charges.
Conclusions:
- The study reveals a rich phase diagram for NCPs, demonstrating complex self-assembly under varying physical conditions.
- The observed polymorphism in NCP supramolecular organization may play a role in chromatin dynamics within cells.
- NCPs' sensitivity to ionic variations highlights their adaptability in biological systems.