TET (ten-eleven translocation) enzymes catalyze the oxidation of 5-methylcytosine bases in DNA, thus driving active and passive DNA demethylation.

The scientists from the Laboratory of Structural Biology at IIMCB report that the catalytic domains of mammalian TET enzymes preferentially oxidize (up to 250-fold) 5mC in certain CG flanking sequences (e.g. CACGTG). Preferred sequences (e.g. E-BOX motif) represent binding sites of basic helix-loop-helix and basic leucine zipper domain transcription factors. They explain the sequence preference in structural terms and show that it influences demethylation rates. "We believe that our findings help to understand the demethylation dynamics in the zygote and  germline - says Prof. Matthias Bochtler, Head of the Laboratory of Structural Biology at IIMCB.

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