Single-molecule multiplexed profiling of protein-DNA complexes using magnetic tweezers

Area of Science:

• Epigenetics
• Molecular Biology
• Biophysics

Background:

• DNA methylation and demethylation are crucial epigenetic mechanisms.
• Enzyme recruitment and DNA recognition by epigenetic enzymes remain poorly understood.
• DNA-binding epigenetic enzymes are underexploited therapeutic targets.

Purpose of the Study:

• To develop a single-molecule technique for multiplexed profiling of protein-DNA interactions.
• To investigate the binding preferences of the TET1 CXXC domain to CpG motifs.
• To understand how DNA sequence and methylation influence enzyme binding dynamics.

Main Methods:

• Development of a single-molecule magnetic tweezers assay.
• Utilizing DNA hairpins with multiple binding sites for multiplexed analysis.
• Measuring site-specific binding probabilities and dissociation times.

Main Results:

• TET1 CXXC domain exhibits distinct binding preferences for CpG motifs based on flanking nucleotides.
• CpG methylation enhances TET1 CXXC recruitment but minimally impacts dissociation.
• The assay successfully distinguished binding to five distinct CpG clusters in a CpG island.

Conclusions:

• The developed single-molecule assay enables high-resolution characterization of protein-DNA interactions.
• This method provides novel insights into the specificity of epigenetic enzyme recognition.
• The technique holds potential for understanding epigenetic regulation and drug target discovery.