Practice question

DNA adenine methyltransferase Dam transfers methyl groups to N6 position of adenine within palindromic sequence GATC widespread in E. coli genome occurring roughly every 256 base pairs randomly. After semiconservative replication, GATC becomes hemimethylated until Dam restores full methylation using S-adenosylmethionine. Transient state distinguishes nascent strand for mismatch repair strand discrimination and participates in origin sequestration via SeqA binding. Methylation does not affect base pairing but influences protein-DNA interactions altering binding affinities. Mutations in dam elevate mutations and asynchronous initiation.