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Author Spotlight: Evaluation of Protein-Condensate Dynamics in Live Human Cells
Published on: January 5, 2024
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Loop extrusion driven volume phase transition of entangled chromosomes.
Tetsuya Yamamoto1, Helmut Schiessel2
1Institute for Chemical Reaction Design and Discovery, Hokkaido University, Sapporo, Japan.
Biophysical Journal
|June 16, 2022
Summary
Condensin
Area of Science:
- Molecular Biology
- Biophysics
Background:
- Mitotic chromosome assembly can occur without nucleosomes.
- Depletion of topoisomerase II (topo II) from reconstituted chromosomes results in undisentangled structures called "sparklers."
Purpose of the Study:
- To elucidate the mechanism behind "sparkler" formation.
- To investigate the role of condensin-mediated loop extrusion in chromosome assembly.
Main Methods:
- Theoretical modeling extending the theory of entangled polymer gels.
- Incorporation of condensin loop extrusion into the theoretical framework.
Main Results:
- Loop extrusion by condensin stiffens entangled DNA networks.
- This stiffening drives a volume phase transition, causing collapse of swollen DNA gels.
- Condensin localization at the periphery and DNA/histone condensation in the core of "sparklers" are explained.
Conclusions:
- Condensin-driven loop extrusion is a key factor in mitotic chromosome assembly.
- The proposed mechanism provides insight into the formation of compact chromosomal structures.
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