Mismatch repair corrects replicative errors

Model for mismatch repair in E. coli. DNA is methylated (Me) at the A residue in the sequence GATC. DNA replication yields a hemimethylated duplex that exists until methylase can modify the newly synthesized strand. The mismatch-repair system makes any necessary corrections based on the sequence found on the methylated strand (original template). MutS, MutH, and MutL are proteins.