A beta subtype methylase, recognizes the double-stranded sequence 5'-GGATCC-3', methylates C-? on both strands. No endonuclease has been identified for this methylase, although it is speculated it might protect against BamHI. a 2'-deoxycytidine in DNA + S-adenosyl-L-methionine = an N(4)-methyl-2'-deoxycytidine in DNA + H(+) + S-adenosyl-L-homocysteine This methylase is encoded on the proviral phage H2. Belongs to the N(4)/N(6)-methyltransferase family. N(4) subfamily.