Helical Coiled Nucleosome Chromosome Architectures during Cell Cycle Progression.

Area of Science:

• Molecular Biology
• Cell Biology
• Structural Biology

Background:

• Recent studies identified an interphase chromosome architecture characterized by a specific coiled nucleosome structure.
• This structure, derived from cryo-preserved electron microscopy (cryo-EM) tomograms, is dispersed throughout the nucleus.
• Computational processing enhanced the resolution of these tomographic images, enabling the extension of the proposed architecture to mitotic chromosomes.

Approach:

• Detailed insights and specific information into coiled nucleosome chromosome architectures were provided.
• The study built upon defined chromosome time-dependent structures to investigate their dynamics.
• Variants of coiled chromosome structures were discussed, potentially defining specific chromosomal regions.

Key Points:

• A helical nucleosome coiled structure, discerned from cryo-EM tomography, was used to model all 46 sequenced human chromosomes.
• These chromosomes, filled with nucleosomes, were placed within micron-sized chromosome territories inside average-sized nuclei.
• The chromosome architecture was modeled for dynamic structures, variations, and centromere complications during chromosome replication.

Conclusions:

• The study proposes a large-scale reorganization of interphase chromosomes based on the uncoiling of mitotic chromosomes during telophase.
• Chromosome territories are organized as micron-sized patches, accommodating complex volume considerations within the nucleus.
• The structures of replicated coiled chromosomes, still attached to centromeres, were unveiled as part of the overall chromosome architecture, allowing seamless cell cycle transitions.