A beta subtype methylase that binds the system-specific DNA recognition site 5'-AGACC-3' and methylates A-3 (of only 1 strand as the other does not have an A residue). DNA restriction requires both the Res and Mod subunits. a 2'-deoxyadenosine in DNA + S-adenosyl-L-methionine = an N(6)-methyl-2'-deoxyadenosine in DNA + H(+) + S-adenosyl-L-homocysteine Homodimer. A heterotetramer with stoichiometry Res(2)Mod(2). This R-M system is also called EcoP1 and EcoP1I. Belongs to the N(4)/N(6)-methyltransferase family. This gene is interrupted by an IS5 insertion sequence in the phage P1 reference proteome UP000008091.