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Updated: Jun 22, 2026
09:47
Visualization of DNA Compaction in Cyanobacteria by High-voltage Cryo-electron Tomography
Published on: July 17, 2018
Structure of toroidal DNA collapsed inside the phage capsid
Amélie Leforestier1, Françoise Livolant
1Laboratoire de Physique des Solides, Centre Nationale de la Recherche Scientifique, Unité Mixte de Recherche 8502, Bât 510, Université Paris-Sud XI, Centre d'Orsay, Orsay Cedex, France.
Summary
DNA toroids formed hexagonal packing, leading to twist walls and altered DNA pitch. This study reveals how DNA structure is influenced by capsid confinement and cation condensation.
Area of Science:
- Structural biology
- Biophysics
- Molecular biology
Background:
- DNA condensation is crucial for packaging within viral capsids.
- Understanding DNA toroidal structures informs genome organization principles.
Purpose of the Study:
- To investigate the structural organization of DNA toroids within bacteriophage capsids.
- To explore the impact of spermine condensation on DNA packing and helical structure.
Main Methods:
- Cryoelectron microscopy was used to visualize DNA structures.
- Partially filled bacteriophage capsids served as confinement environments.
- Spermine was used as a tetravalent cation to condense DNA.
Main Results:
- DNA toroids exhibited hexagonal packing under specific conditions.
- Frustration between DNA chirality and hexagonal packing induced twist walls.
- DNA helical pitch varied due to helix curvature and correlations.
Conclusions:
- Chirality and hexagonal packing are key factors in DNA toroid formation.
- Twist walls are a consequence of competing structural constraints.
- DNA structure is adaptable within confined viral environments.
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