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Updated: Jul 13, 2026

Direct Observation of Enzymes Replicating DNA Using a Single-molecule DNA Stretching Assay
Published on: March 23, 2010
Fast dynamics of supercoiled DNA revealed by single-molecule experiments
Aurélien Crut1, Daniel A Koster, Ralf Seidel
1Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Abstract:
The dynamics of supercoiled DNA play an important role in various cellular processes such as transcription and replication that involve DNA supercoiling. We present experiments that enhance our understanding of these dynamics by measuring the intrinsic response of single DNA molecules to sudden changes in tension or torsion. The observed dynamics can be accurately described by quasistatic models, independent of the degree of supercoiling initially present in the molecules. In particular, the dynamics are not affected by the continuous removal of the plectonemes. These results set an upper bound on the hydrodynamic drag opposing plectoneme removal, and thus provide a quantitative baseline for the dynamics of bare DNA.
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