Toxic component of a contact-dependent interbacterial competition system (also called effector-immunity systems). Acts by ADP-ribosylating a number of target proteins in target cells; E.coli target proteins include FtsZ, EFTu, RNase E, Fis, YegQ, GuaB and IF2. L-arginyl-[protein] + NAD(+) = H(+) + N(omega)-(ADP-D-ribosyl)-L-arginyl-[protein] + nicotinamide Probably delivered to target cells by a type 6 secretion system (T6SS). The ART domain is toxic when expressed as a protein fragment. Belongs to the Arg-specific ADP-ribosyltransferase family.