Quantifying transcription factor specificity with advanced DNA universal microarrays featuring long and modified...

Area of Science:

• Molecular Biology
• Genomics
• Epigenetics

Background:

• Transcription factor (TF) DNA binding specificity is crucial for gene regulation.
• Universal protein-binding microarrays (uPBMs) are used to study TF specificity but are limited to short DNA motifs and canonical bases.
• Existing methods cannot resolve the impact of extended sequence context or epigenetic modifications on TF binding.

Purpose of the Study:

• To develop enhanced platforms for TF-DNA binding analysis that overcome the limitations of conventional uPBMs.
• To enable direct measurement of longer DNA motifs and the effects of modified bases on TF binding specificity.
• To provide a more comprehensive understanding of TF binding dynamics in gene regulation.

Main Methods:

• Development of Ex-uPBM (extended higher-order de Bruijn sequences) for longer motif analysis.
• Development of Mod-uPBM (de Bruijn sequences with modified bases) for epigenetic modification studies.
• Application of Ex-uPBM and Mod-uPBM to measure TF binding to extended and modified DNA sequences.

Main Results:

• Ex-uPBM allowed direct measurement of motifs up to 10 bp and revealed specificity to flanking regions.
• Mod-uPBM quantified the energetic effects of 5-methylcytosine (5mC) in all sequence contexts.
• A full energetic position weight matrix (PWM) revealed context-specific 5mC effects at single-nucleotide resolution.

Conclusions:

• Ex-uPBM and Mod-uPBM offer robust and scalable strategies for TF binding quantification.
• These platforms capture sequence and modification complexity beyond standard uPBM capabilities.
• The enhanced methods provide deeper insights into the mechanisms of gene regulation by TFs.