Fig. 1
Action of ten-eleven translocation (TET) and Jumonji C (JmjC) enzymes. a Cytosine is converted to 5-methylcytosine (5mC) by the addition of a methyl group by DNA methyltransferase enzymes (DNMTs). TET enzymes successively oxidise 5mC to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Base excision repair (BER) machinery excise and replace the intermediates with unmethylated cytosine. b TET enzymes require 2-oxoglutarate (2-OG), Fe2+ and molecular oxygen (O2) for their DNA demethylase activity. c Histone methyltransferases (HMTs) can deposit either repressive or activating methyl marks depending on which site is methylated and to what extent (mono/di/trimethylation). This results in a ‘closed’ and ‘open’ conformation of chromatin, respectively. Hence, the removal of methyl groups by JmjCs can result in the activation or repression of a gene. d JmjC enzymes require 2-oxoglutarate (2-OG), Fe2+ and molecular oxygen (O2) for their histone lysine demethylase activity