Figure 3. Cytosine methylation at codon 248 (-CGG-) of p53 gene sensitizes codon 249 (-AGG-) for Acet and Cro modifications.

Single 5’-end A. or 3’-end B. ³²P labeled exon 7 p53 DNA fragments were methylated with CpG methylase, as previously described [13, 61] then modified with Acet (100 μM, 1 h at 25 °C) and Cro (100 μM, 1 h at 37°C). PdG distributions in the fragments were mapped by the UvrABC incision method [26]. ∧C and C represent the methylated and unmethylated DNA fragments, respectively. * indicates the UvrABC incised base. C. The effect of methylation on Acet and Cro induced PdG formation. The relative levels of PdG formation at different sequences of 3’-end ³²P-labled exon 7 of p53 gene fragments with (Methyl) and without (Un-methyl) CpG methylation as shown in (B) were quantified as described [13, 36]. RI represents relative intensity. Note: CpG methylation greatly enhances Acet- and Cro-induced PdG formation at codon 249.