Hydroxylation of methylated CpG dinucleotides reverses stabilisation of DNA duplexes by cytosine 5-methylation.
Thalhammer A., Hansen AS., El-Sagheer AH., Brown T., Schofield CJ.
Cytosine-5-methylation stabilises DNA duplexes and is associated with transcriptional repression; 5-methylcytosine undergoes hydroxylation to 5-hydroxymethylcytosine, a modification of unknown biological function. Spectroscopic and calorimetric analyses show that 5-hydroxymethylcytosine introduction reverses the stabilising effect of 5-methylcytosine, suggesting that in some contexts, 5-methylcytosine hydroxylation may, along with other factors, contribute to the alleviation of transcriptional repression.