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Viral Nucleosome-Like Particles Exhibit Dynamic Flexibility and Reduced Thermodynamic Stability
Melanie Melo1,2, Jeff Wereszczynski1,2
1Department of Physics, Illinois Institute of Technology, Chicago, USA.
Biorxiv : the Preprint Server for Biology
|August 8, 2025
Summary
Large DNA viruses package their genomes differently than eukaryotes. Viral nucleosomes show increased DNA unwrapping and weaker histone-DNA contacts due to altered histone structures, revealing unique viral chromatin dynamics.
Area of Science:
- Structural biology
- Biophysics
- Genomics
Background:
- Eukaryotic DNA is packaged by nucleosomes, involving histones with flexible tails for compaction and gene accessibility.
- Large DNA viruses utilize nucleosome-like particles with distinct histone architectures, lacking canonical tails and featuring fused domains.
Purpose of the Study:
- To investigate the biophysical properties and structural dynamics of viral chromatin using the Melbournevirus nucleosome as a model.
- To understand how viral histone fusion, tail loss, and connector architecture influence DNA packaging and accessibility.
Main Methods:
- Multi-microsecond all-atom molecular dynamics simulations were employed.
- Analysis focused on structural and thermodynamic behavior of the Melbournevirus nucleosome.
Main Results:
- Viral nucleosomes exhibit enhanced DNA unwrapping compared to eukaryotic counterparts.
- Histone-DNA contacts in viral systems are weaker and more transient.
- Localized flexibility at histone connector regions and conformational adaptation at histone junctions were observed.
Conclusions:
- Viral chromatin organization differs significantly from eukaryotic nucleosomes due to unique histone structures.
- These differences impact DNA dynamics and accessibility, reflecting evolutionary adaptations in viral genome packaging.
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