Near-atomic resolution structures of interdigitated nucleosome fibres

Area of Science:

• Molecular Biology
• Epigenetics
• Structural Biology

Background:

• Chromosome structure at the multi-nucleosomal level is crucial for epigenetic regulation and genome dynamics.
• Existing models of chromatin architecture lack atomic-level resolution for nucleosome fiber interactions.

Purpose of the Study:

• To elucidate the atomic-level structure of nucleosome fibers.
• To understand how nucleosome chain interactions contribute to higher-order chromosome organization.

Main Methods:

• Near-atomic resolution crystal structures were determined for nucleosome fibers.
• Fibers were assembled from cohesive-ended dinucleosomes, with and without linker histone.

Main Results:

• Nucleosome fibers adopt open zigzag conformations, not folded helical structures.
• These zigzag fibers interdigitate, with linker DNA length dictating fiber configuration and packing.
• Linker histone binding modulates fiber-fibre packing.

Conclusions:

• Nucleosome chains exhibit a predisposition for interdigitation under condensing conditions.
• The zigzag conformation explains local chromosome architecture and chromatin heterogeneity.
• This finding provides atomic insights into epigenetic regulation and genome dynamics.