A beta subtype methylase that binds the system-specific DNA recognition site 5'-CAGCAG-3' and methylates A-5 (of only 1 strand as the other does not have an A residue). DNA restriction requires both the Res and Mod subunits (PubMed:11178902, PubMed:12654995). The A-5 nucleotide flips into the catalytic pocket of one Mod subunit for modification, while the other Mod subunit makes most of the DNA sequence-specific contacts (PubMed:26067164). a 2'-deoxyadenosine in DNA + S-adenosyl-L-methionine = an N(6)-methyl-2'-deoxyadenosine in DNA + H(+) + S-adenosyl-L-homocysteine Forms a homodimer capable of methylating the target sequence in the absence of Res (Probable). A heterotetramer with stoichiometry Res(2)Mod(2) (PubMed:11178902). A heterotrimer with stoichiometry Res(1)Mod(2) (PubMed:26067164). This R-M system is also called EcoP15. Belongs to the N(4)/N(6)-methyltransferase family.