Fig. 1. Illustration of the deamination of cytosine, 4mC and 5mC by A3A protein. (A) Cytosine and 5mC are deaminated to form uracil and thymine that pair with adenine. 4mC is resistant to deamination by A3A and thus still pairs with guanine. (B) Schematic illustration of the single-base resolution mapping of 4mC in DNA by the 4mC-AMD-seq method. A3A treatment leads to the deamination of C and 5mC to form U and T, respectively. Both U and T are read as T in sequencing. However, A3A will not deaminate 4mC. Thus, 4mC is read as C in sequencing.
