Orphan immunity component of an interbacterial competition system (also called effector-immunity systems); this bacteria does not encode an identifiable cognate effector protein. Expression of this protein in E.coli partially protects the cells against competition by wild-type S.proteamaculans (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 (Probable). H2O + N(omega)-(ADP-D-ribosyl)-L-arginyl-[protein] = ADP-D-ribose + L-arginyl-[protein] Binds 1 Mg(2+) ion per subunit. Decreased fitness in interbacterial competition assays against S.proteamaculans. Belongs to the ADP-ribosylglycohydrolase family.