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Updated: Jun 4, 2026

Analyzing and Building Nucleic Acid Structures with 3DNA

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Published on: April 26, 2013

Deciphering the structure of DNA toroids.

Laurence R Brewer¹

¹The Voiland School of Chemical Engineering and Bioengineering, Center for Reproductive Biology, Washington State University, Pullman, WA 99164-2710, USA. brewerl@wsu.edu

Integrative Biology : Quantitative Biosciences From Nano to Macro

|February 16, 2011

Summary

This summary is machine-generated.

Toroids, donut-shaped DNA structures in sperm and viruses, are now understood to form via stepwise DNA loop incorporation. This process increases DNA tension, influencing toroid structure and genome organization.

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Area of Science:

Structural Biology
Biophysics
Genomics

Background:

Toroids are organizational units in sperm chromatin and viruses, housing DNA and proteins.
Previous microscopy techniques limited understanding of toroid assembly and biomechanics.
Bulk DNA studies were hindered by aggregation issues.

Purpose of the Study:

To investigate the structure and formation of DNA toroids.
To understand the biomechanical forces involved in toroid assembly.
To explore DNA organization within sperm and viruses.

Main Methods:

Transmission electron microscopy (TEM)
Atomic force microscopy (AFM)
Cryo-electron microscopy (Cryo-EM)
Optical and magnetic traps for single DNA molecule manipulation

Main Results:

Observed hexagonal DNA organization in viruses and DNA-cobalt hexammine toroids.
Demonstrated toroids consist of DNA loops incorporated stepwise.
Showed toroid formation increases DNA tension, reducing loop size.

Conclusions:

Single-molecule techniques provide new insights into toroid structure and assembly.
Understanding toroid formation is crucial for genomic DNA organization in cells and viruses.
Emerging technologies hold potential for answering remaining questions about toroids.