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Related Experiment Video

Updated: May 11, 2026

Studying DNA Looping by Single-Molecule FRET

Studying DNA Looping by Single-Molecule FRET

Published on: June 28, 2014

Measuring shape-dependent looping probability of DNA.

Tung T Le¹, Harold D Kim

¹School of Physics, Georgia Institute of Technology, Atlanta, Georgia, USA.

Biophysical Journal

|May 14, 2013

Summary

Short DNA loops form faster than predicted, suggesting current models don't fully capture DNA's intrinsic shape and its effect on looping dynamics.

Area of Science:

Molecular Biology
Biophysics
Structural Biology

Background:

Short DNA loops form more readily than predicted by the wormlike chain model.
The intrinsic curvature of double-stranded DNA (dsDNA) can significantly impact looping dynamics but is often overlooked.
Previous experiments did not fully account for dsDNA's inherent shape.

Purpose of the Study:

To investigate how the intrinsic shape of dsDNA influences its looping dynamics.
To characterize the shapes of synthetic dsDNA molecules with varying sequences but equal lengths.
To compare measured looping rates with theoretical predictions based on DNA shape.

Main Methods:

Gel electrophoresis was used to characterize the shapes of synthetic dsDNA molecules.
Förster resonance energy transfer (FRET)-based assays measured DNA looping rates.

Related Experiment Videos

Last Updated: May 11, 2026

Studying DNA Looping by Single-Molecule FRET

Studying DNA Looping by Single-Molecule FRET

Published on: June 28, 2014

The J factor (jM), a measure of looping probability, was extracted from experimental data.

Dinucleotide angular parameters derived from gel mobility were used to predict jM via the wormlike chain model.

Main Results:

A strong correlation was observed between DNA curvature and the measured J factor (jM).
Measured jM values were consistently higher than predictions from most dinucleotide models.
Discrepancies suggest limitations in reconciling looping probability with gel mobility using the wormlike chain model.

Conclusions:

The intrinsic shape of dsDNA is crucial for accurately analyzing looping dynamics.
Current models struggle to reconcile observed looping probabilities with DNA shape data derived from gel electrophoresis.
Further research is needed to integrate intrinsic DNA shape into theoretical models of DNA looping.