A type III restriction enzyme that recognizes 2 inversely oriented double-stranded sequences 5'-AGACC-3' and cleaves DNA 25-27 base pairs downstream of one site, producing a single-strand 5' protrusion of two nucleotides. DNA restriction requires both the Res and Mod subunits (PubMed:2837577, PubMed:11178902). DNA topology affects its action; relaxed and negatively supercoiled DNA are digested but positively supercoiled DNA is not a good substrate (PubMed:11178902). After binding to one recognition site undergoes random one-dimensional diffusion along DNA until it collides with a stationary enzyme bound to the second DNA site, which is when DNA cleavage occurs (By similarity). Endonucleolytic cleavage of DNA to give specific double-stranded fragments with terminal 5'-phosphates. A heterotetramer with stoichiometry Res(2)Mod(2). Has a helicase-type domain in its N-terminus and an endonuclease-type domain in its C-terminus; ATP and DNA hydrolysis activities are mediated by the N- and C-terminal domains respectively. The C-terminus is probably required for interaction with the Mod subunit; deletion of residues 897-970 is unstable as is this protein when expressed alone. This R-M system is also known as EcoP1 and EcoP1I. Belongs to the type III restriction-modification system Res protein family.