Probing DNA - Transcription Factor Interactions Using Single-Molecule Fluorescence Detection in Nanofluidic Devices

Area of Science:

• Biophysics
• Molecular Biology
• Plant Science

Background:

• Single-molecule fluorescence detection is crucial for studying biomolecular interactions.
• Plant transcription factors, like auxin response factors (ARFs), regulate gene expression through DNA binding.
• Understanding ARF-DNA interactions is key to deciphering plant growth and development pathways.

Purpose of the Study:

• To investigate the interactions between plant ARF DNA binding domains (ARF-DBDs) and their target DNA response elements.
• To utilize nanofluidic devices and single-molecule Förster resonance energy transfer (smFRET) for high-resolution analysis.
• To determine the oligomeric state of ARF-DBDs during DNA binding.

Main Methods:

• Integration of nanofluidic devices with camera-based single-molecule Förster resonance energy transfer (smFRET) detection.
• Monitoring changes in FRET efficiency and diffusion coefficients of DNA oligonucleotides upon ARF-DBD binding.
• Utilizing fluorescently labeled ARF-DBDs and DNA oligonucleotides.

Main Results:

• Successfully detected the binding of unlabeled ARF-DBDs to labeled DNA via smFRET.
• Observed changes in FRET efficiency and DNA diffusion coefficient indicating ARF-DBD binding.
• Data suggests ARF-DBDs exist exclusively as monomers at nanomolar concentrations.
• Demonstrated the ability to study ARF-DBD monomer-DNA interactions.

Conclusions:

• Nanofluidic smFRET is a powerful technique for studying transcription factor-DNA interactions.
• ARF-DBDs function as monomers when interacting with their DNA response elements.
• The freely diffusing molecule approach in nanofluidics minimizes artifacts and enables high-throughput analysis of molecular interactions.