Sequencing the Sixth Base (5-Hydroxymethylcytosine): Selective DNA Oxidation Enables Base-Pair Resolution


  • We thank the Helmholtz Drug Research Initiative for funding (P.S.) and the program “epigenetics@dkfz”.


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Sodium bisulfite promotes both the deformylative deamination of 5-formylcytosine (5fC) and the decarboxylative deamination of 5-carboxylcytosine (5caC; see picture). By coupling this bisulfite chemistry with selective oxidations of individual DNA bases, new methods allow, for the first time, the sequencing of 5-hydroxymethylcytosine (5hmC) with single-base-pair resolution.