InterPro: IPR012186 Adenine modification methylase, M.StsI

In prokaryotes, the major role of DNA methylation is to protect host DNA against degradation by restriction enzymes. Adenine modification methylases are a large group of enzymes, most of which form so-called 'restriction-modification systems'. Methylation of specific adenine residues is required for both restriction and modification activities. This methylase catalyses the reaction:

S-adenosyl-L-methionine + DNA adenine = S-adenosyl-L-homocysteine + DNA 6-methylaminopurine

It recognises the double-stranded sequence 5'-GGATG-3' in one strand and 3'-CATCC-5' in the other, causing specific methylation on the A of both strands. This protects the DNA from cleavage by the FokI endonuclease. The 2 domains of the protein participate in the modification of the two strands.

This group represents a modification methylase (adenine-specific), M.StsI type.