Figure 8.

The consequences of recognition site hemi-methylation following replication, adapted from the model of Meisel et al.(32,33). The LlaGI site is indicated as an arrowhead (Figure 1C), the methylated site by a circle and the newly synthesised DNA in red. (A) Where two sites are in head-to-head repeat, one site of the pair is methylated in each of the daughter DNAs and both are protected from dsDNA cleavage (Figure 7). (B) With two sites in head-to-tail repeat, both sites in one daughter DNA are completely unmethylated. However, this arrangement of sites does not result in a dsDNA break (Figures 3 ands 4). DNA nicking that result from the unmethylated sites is likely to be repaired before the replication fork next passes.