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Updated: Aug 18, 2026

High Sensitivity Measurement of Transcription Factor-DNA Binding Affinities by Competitive Titration Using Fluorescence Microscopy
Published on: February 7, 2019
Mechanics of binding of a single integration-host-factor protein to DNA
Sanhita Dixit1, Mukta Singh-Zocchi, Jeungphill Hanne
1Department of Physics and Astronomy, University of California-Los Angeles, Los Angeles, CA 90095-1547, USA.
Abstract:
We report on a single-molecule experiment where we directly observe local bending of a 76 base pair DNA oligomer caused by specific binding of a single integration-host-factor (IHF) protein. The conformational change of the DNA is detected by optically monitoring the displacement of a micron size bead tethered to a surface by the DNA. Since in the bound state the DNA loops around the IHF, a mechanical tension on the DNA tends to eject the protein. We measure how the rate for the protein to fall off the DNA depends on the mechanical tension in the DNA, gaining insight into the energy landscape for this molecular bond. Our method further demonstrates a new paradigm of molecular detection, where ligand binding is detected through the conformational change induced in the probe molecule. Here this allows the detection of single, unlabeled proteins.
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Single-Strand DNA Binding Proteins
Cooperative Binding of Transcription Regulators
Cooperative Binding of Transcription Regulators
Activation of Integrins
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
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