Pronounced sequence specificity of the TET enzyme catalytic domain guides its cellular function

Area of Science:

• Epigenetics
• Molecular Biology
• Biochemistry

Background:

• Ten-eleven translocation (TET) enzymes are crucial for active and passive DNA demethylation.
• DNA demethylation is a key epigenetic mechanism regulating gene expression.

Purpose of the Study:

• To investigate the sequence preferences of mammalian TET enzymes.
• To understand the molecular basis and physiological relevance of TET sequence specificity.

Main Methods:

• In vitro biochemical assays to determine enzyme preference.
• Crystal structures and molecular dynamics simulations to elucidate mechanism.
• Analysis of TET-rescue experiments in cell culture and in vivo.

Main Results:

• Mammalian TET enzymes exhibit a significant preference (up to 250-fold) for CGs within basic helix-loop-helix and basic leucine zipper transcription factor binding sites.
• Sequence preference is driven by intrasubstrate interactions and indirect effects of flanking sequences on enzyme conformation.
• TET sequence preferences correlate with DNA demethylation rates in various experimental systems, including zygotes and germ lines.

Conclusions:

• TET enzyme sequence specificity is a critical determinant of DNA demethylation patterns.
• Favorable TET motifs are associated with methylation-sensitive transcription factors, while least favorable motifs bind OCT4.
• These findings illuminate TET enzyme roles in transcriptional regulation and maintaining pluripotency.