A gamma subtype methylase that recognizes the double-stranded sequence 5'-CTGCAG-3', methylates A-5 on both strands, and protects the DNA from cleavage by the PstI endonuclease. a 2'-deoxyadenosine in DNA + S-adenosyl-L-methionine = an N(6)-methyl-2'-deoxyadenosine in DNA + H(+) + S-adenosyl-L-homocysteine Monomer. Belongs to the N(4)/N(6)-methyltransferase family.