Near-atomistic simulations reveal the molecular principles that control chromatin structure and phase separation

Area of Science:

• Biophysics
• Molecular Biology
• Genomics

Background:

• Chromatin organization is crucial for genome function.
• Understanding the physicochemical basis of chromatin structure is essential.
• Current simulation methods are limited in scale and detail.

Purpose of the Study:

• To develop a high-performance coarse-grained model for simulating large chromatin systems.
• To link molecular-level interactions to emergent chromatin organization.
• To investigate the role of linker DNA and histone tails in chromatin structure and dynamics.

Main Methods:

• Development of the OpenCGChromatin model for near-atomistic simulations.
• Simulating chromatin systems orders of magnitude larger than previously possible.
• Investigating histone tail dynamics, interaction networks, and acetylation effects.

Main Results:

• OpenCGChromatin accurately predicts linker-DNA-dependent chromatin structures and condensate stability.
• The model elucidates how linker DNA length influences histone tail accessibility and chromatin structure.
• Acetylation, particularly at H4K16 and H3K9, was shown to disrupt chromatin compaction by weakening specific interactions.

Conclusions:

• OpenCGChromatin provides a powerful framework for bridging molecular detail and emergent chromatin organization.
• The study explains the multiscale structure of chromatin condensates based on physicochemical principles.
• Findings offer insights into epigenetic regulation and genome function.