Related Experiment Videos
Aggregation of small oligonucleosomal chains into 300-A globular particles
Summary
Chicken erythrocyte chromatin, specifically oligonucleosomes, self-assemble into globular particles via lysine-rich histones H1 and H5. These dynamic structures are sensitive to salt concentration and remain in equilibrium with their components.
Area of Science:
- Molecular Biology
- Chromatin Structure
- Biophysics
Background:
- Chromatin is the complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells.
- Histones are key proteins involved in chromatin packaging, with lysine-rich histones (H1 and H5) playing a role in higher-order structure.
Purpose of the Study:
- To investigate the self-assembly of chicken erythrocyte oligonucleosomes into higher-order structures.
- To characterize the properties and stability of these assembled particles.
Main Methods:
- Micrococcal nuclease digestion of chicken erythrocyte chromatin.
- Analysis of chromatin self-assembly in the presence of 30 mM NaCl.
- Determination of particle size and sensitivity to ionic strength.
Main Results:
- Oligonucleosomes (trimers to 20-mers) spontaneously form heterogeneous globular particles (approx. 300 A diameter) containing ~25 nucleosomes.
- Particle formation is mediated by lysine-rich histones H1 and H5.
- These particles are dynamic, sensitive to ionic strength, and can be reconstituted by adjusting salt concentration.
Conclusions:
- Lysine-rich histones facilitate the self-assembly of oligonucleosomes into dynamic, globular higher-order structures.
- The stability of these particles is dependent on both ionic strength and the concentration of oligonucleosomal components.