DNA mismatch repair MutH (SM00927) is responsible for repairing DNA mismatches. Three important proteins-MutS, MutL, and MutH-start methyl-directed DNA mismatch repair in Escherichia coli to fix mistakes that happen during DNA replication. In a hemimethylated duplex, MutH cleaves the newly synthesized unmethylated daughter strand 5' to the sequence d (GATC). In order to activate MutH PUBMED:9482749, MutS and MutL must recognize DNA mismatches.