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Updated: Jul 10, 2026
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Single-Molecule Real-Time Visualization of DNA Unwinding by CMG Helicase
Published on: September 27, 2024
Double-stranded DNA dissociates into single strands when dragged into a poor solvent.
Shuxun Cui1, Jin Yu, Ferdinand Kühner
1State Key Lab of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, People's Republic of China. cuisx@scu.edu.cn
Journal of the American Chemical Society
|November 7, 2007
Summary
Dragging double-stranded DNA (dsDNA) into a poor solvent causes strand separation. This unwinding mechanism in low-polarity environments may be key to helicase function.
Area of Science:
- Biochemistry
- Molecular Biology
- Biophysics
Background:
- DNA exhibits diverse supramolecular structures influenced by sequence and environment.
- The structural response of double-stranded DNA (dsDNA) to poor solvents remains poorly understood due to condensation effects.
Purpose of the Study:
- To investigate structural and mechanical changes in DNA when transitioning from water to a poor solvent.
- To elucidate the mechanism of DNA strand separation under altered ambient conditions.
Main Methods:
- Single-molecule atomic force microscopy (AFM) was employed to observe DNA behavior.
- Molecular dynamics (MD) simulations were utilized to model and confirm the observed phenomena.
Main Results:
- Pulling dsDNA from water into a poor solvent induced the separation of its two strands.
- MD simulations corroborated these findings, detailing strand separation at the water/poor solvent interface.
Conclusions:
- DNA's high polarity makes it susceptible to unwinding/splitting in low-polarity (hydrophobic) environments.
- This spontaneous dsDNA splitting mechanism may be exploited by helicases for catalysis.
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