SHORT ANSWER: Changing DNA methylation levels can control its replication. In fact, if both DNA strands are methylated, DNA replication begins, but if only one of the two strands is methylated (hemimethylation), DNA replication is prevented from starting.
What is the role of methylation in cell cycle control?
1- In the oriC region of the genome, GATC nucleotide sequences are methylated by the enzyme dam methylase. The dam methylase enzyme transfers a methyl group from S-adenosylmethionine to the adenine nucleotide in the GATC sequence.
2-Methylation plays a crucial role in DNA replication by removing incorrect base sequences that can occur during the process. The mismatch repair system in cells distinguishes between the newly replicated strand, where errors occur, and the correct sequence on the template strand by marking the parental strand with a methyl group. Each round of DNA replication produces two hemi-methylated copies of the genome, which need to be converted back to symmetrically methylated DNA before the next S-phase. Methylation is a chemical modification of DNA that can change gene expression.
