Transcription Factor Binding in Embryonic Stem Cells Is Constrained by DNA Sequence Repeat Symmetry

Area of Science:

• Molecular Biology
• Genetics
• Biophysics

Background:

• Transcription factor (TF) recognition traditionally relies on specific DNA motif sequences.
• The role of broader DNA sequence features, like repeat symmetry, in TF binding remains less understood.
• Understanding TF-DNA interactions is crucial for deciphering gene regulation.

Purpose of the Study:

• To investigate the role of DNA sequence repeat symmetry in defining transcription factor-DNA binding preferences.
• To explore how these symmetry patterns influence gene expression during cellular differentiation.
• To identify novel regulatory elements beyond canonical TF motifs.

Main Methods:

• Analysis of TF-DNA binding preferences across different developmental contexts.
• In vivo reporter assays to assess the impact of DNA sequences on gene expression in embryonic stem cells.
• Solution NMR experiments to evaluate DNA duplex stability associated with repetitive sequences.

Main Results:

• DNA sequence repeat symmetry is a key determinant of TF-DNA binding preferences, often overriding specific motif sequences.
• Similar symmetry patterns are recognized by different TFs and are conserved across developmental layers, with some changes during differentiation.
• Nonconsensus-repetitive DNA elements can functionally modulate gene expression, and their stability correlates with TF binding.
• Histone modifications also show distinct preferences for specific DNA repeat symmetry patterns.

Conclusions:

• DNA sequence repeat symmetry provides a fundamental framework for understanding the complex TF-DNA binding landscape.
• Beyond canonical motifs, repetitive DNA elements possess regulatory functions and influence gene expression.
• The concept of DNA repeat symmetry offers a simplified, quantitative approach to characterizing TF-DNA interactions.