Bisulfite-Free Sequencing of 5-Hydroxymethylcytosine with APOBEC-Coupled Epigenetic Sequencing (ACE-Seq)

Here, we provide a detailed protocol for our previously published technique, APOBEC-Coupled Epigenetic Sequencing (ACE-Seq), which localizes 5-hydroxymethylcytosine at single nucleotide resolution using nanogram quantities of input genomic DNA. In addition to describing suggested troubleshooting workflows, these methods include four important updates which should facilitate widespread implementation of the technique: (1) additionally optimized reaction conditions; (2) redesigned quality controls which can be performed prior to resource-consumptive deep sequencing; (3) confirmation that the less active, uncleaved APOBEC3A (A3A) fusion protein, which is easier to purify, can be used to perform ACE-Seq ; and (4) an example bioinformatic pipeline with suggested filtering strategies. Finally, we have provided a supplementary video which gives a narrated overview of the entire method and focuses on how best to perform the snap cool and A3A deamination steps central to successful execution of the method.