A beta subtype methylase, recognizes the double-stranded sequence 5'-ATGCAT-3' and methylates A-5. a 2'-deoxyadenosine in DNA + S-adenosyl-L-methionine = an N(6)-methyl-2'-deoxyadenosine in DNA + H(+) + S-adenosyl-L-homocysteine Mutants are viable and show no significant growth deficiency and no alteration of cell morphology. Belongs to the N(4)/N(6)-methyltransferase family. Extended N-terminus.