Immunity component of an interbacterial competition system (also called effector-immunity systems). Expression in E.coli neutralizes the toxic effects of non-cognate S.proteamaculans effector protein Tre1 (Tre1-Sp); cannot be co-purified with Tre1-Sp from E.coli, suggesting they do not form a stable complex (PubMed:30343895). Probably acts as an arginine mono-ADP-ribosylhydrolase, mediating the removal of mono-ADP-ribose attached to arginine residues on proteins. Probably de-ADP-ribosylates FtsZ and possibly other proteins; the ability to hydrolyze ADP-ribosyl moieties is not essential for neutralization of its cognate toxin, strongly suggesting its N-terminal extension occludes the active site of cognate toxin Tre1 (Probable). H2O + N(omega)-(ADP-D-ribosyl)-L-arginyl-[protein] = ADP-D-ribose + L-arginyl-[protein] Binds 1 Mg(2+) ion per subunit. The N-terminal extension probably forms a projection that reaches into the active site of cognate toxin Tre1-Pp where it occludes the active site. Belongs to the ADP-ribosylglycohydrolase family.