Light-Activatable TET-Dioxygenases Reveal Dynamics of 5-Methylcytosine Oxidation and Transcriptome Reorganization.

Ten-eleven-translocation (TET) dioxygenases catalyze the oxidation of 5-methylcytosine (5mC), the central epigenetic regulator of mammalian DNA. This activity dynamically reshapes the epigenome and transcriptome by depositing oxidized 5mC derivatives and initiating active DNA demethylation. However, studying this dynamic is hampered by the inability to selectively activate individual TETs with temporal control in cells. We report activation of TETs in mammalian cells by incorporation of genetically encoded 4,5-dimethoxy-2-nitrobenzyl-l-serine as a transient active-site block, and its subsequent deprotection with light. Our approach enables precise insights into the impact of cancer-associated TET2 mutations on the kinetics of TET2 catalysis