InterPro: IPR002941 DNA methylase N-4/N-6

This domain is found in DNA methylases. In prokaryotes, the major role of DNA methylation is to protect host DNA against degradation by restriction enzymes. This family contains both N-4 cytosine-specific DNA methylases and N-6 Adenine-specific DNA methylases. N-4 cytosine-specific DNA methylases (EC:2.1.1.113) [1] are enzymes that specifically methylate the amino group at the C-4 position of cytosines in DNA. Such enzymes are found as components of type II restriction-modification systems in prokaryotes. Such enzymes recognise a specific sequence in DNA and methylate a cytosine in that sequence. By this action they protect DNA from cleavage by type II restriction enzymes that recognise the same sequence. N-6 adenine-specific DNA methylases (EC:2.1.1.72) (A-Mtase) are enzymes that specifically methylate the amino group at the C-6 position of adenines in DNA. Such enzymes are found in the three existing types of bacterial restriction-modification systems (in type I system the A-Mtase is the product of the hsdM gene, and in type III it is the product of the mod gene). All of these enzymes recognise a specific sequence in DNA and methylate an adenine in that sequence.