A beta subtype methylase that recognizes the single- or double-stranded sequence 5'-GATC-3', methylates A-2 on one or both strands (respectively), and protects the DNA from cleavage by the DpnII endonuclease. Further methylates DNA that is already methylated at 5'-GATC-3' sites. Essential for establishment of a previously unmethylated plasmid transformed into the cell as single-stranded DNA, enhances plasmid transfer to DpnII-containing strains of Streptococcus pneumoniae. a 2'-deoxyadenosine in DNA + S-adenosyl-L-methionine = an N(6)-methyl-2'-deoxyadenosine in DNA + H(+) + S-adenosyl-L-homocysteine Homodimer. The DpnII restriction system has two different methylases. Produced in response to the induction of competence for genetic transformation. Belongs to the N(4)/N(6)-methyltransferase family.