InterPro: IPR001091 Site-specific DNA-methyltransferase (cytosine-N4-specific)

Synonym(s): N-4 cytosine-specific DNA methylase, Modification methylase

Site-specific DNA-methyltransferase (cytosine-N4-specific) (EC:2.1.1.113) are enzymes that specifically methylate the amino group at the C-4 position of cytosines in DNA. In prokaryotes, the major role of DNA methylation is to protect host DNA against degradation by restriction enzymes. There are two major classes of DNA methyltransferase that differ in the nature of the modifications they effect. The members of one class (C-MTases) methylate a ring carbon and form C5-methylcytosine and members of the second class (N-MTases) methylate exocyclic nitrogens and form either N4-methylcytosine (N4-MTases) or N6-methyladenine (N6-MTases). Both classes of MTase utilise the cofactor S-adenosyl-L-methionine (SAM) as the methyl donor and are active as monomeric enzymes [1].