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Structure and Dynamics of Compact Dinucleosomes: Analysis by Electron Microscopy and spFRET
Maria E Stefanova1, Olesya I Volokh1, Oleg V Chertkov1
1Biology Faculty, Lomonosov Moscow State University, Moscow 119234, Russia.
International Journal of Molecular Sciences
|August 12, 2023
Summary
Compact dinucleosomes (CODIs) are dynamic structures where nucleosomal DNA can uncoil from histone octamers. This destabilization, influenced by spacing, suggests CODIs may be intermediates in chromatin disruption.
Area of Science:
- Molecular biology
- Chromatin dynamics
- Epigenetics
Background:
- Compact dinucleosomes (CODIs) form at active regulatory DNA regions.
- The structural heterogeneity and dynamics of CODIs remain poorly understood.
Purpose of the Study:
- To investigate the structure and dynamics of CODIs.
- To determine the role of internucleosomal spacing in chromatin stability.
Main Methods:
- Single-particle Förster resonance energy transfer (spFRET) microscopy in solution and gel.
- Electron microscopy analysis.
Main Results:
- A fraction of CODIs exhibit significant uncoiling of nucleosomal DNA from the histone octamer.
- Electron microscopy suggests up to 30 bp of DNA transiently uncoil/recoil on the histone octamer.
- The histone chaperone Spt6 does not stabilize the more open nucleosome structure in CODIs.
Conclusions:
- CODIs display structural heterogeneity and dynamics, with some nucleosomes being destabilized.
- Proper internucleosomal spacing is crucial for maintaining chromatin stability.
- CODIs may serve as intermediates in chromatin disruption processes.
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