Selected because Arr is a classic rifampin-inactivation enzyme with essentially no useful GOA coverage in the fetched file. UniProt O67972 names it "Rifampin ADP-ribosyl transferase" and cross-references CARD arr-1 as antibiotic inactivation [file:genes/MYCSM/arr/arr-uniprot.txt]. The original M. smegmatis paper states that the organism inactivates rifampin by ribosylating it, that the cloned gene confers low-level resistance, and that targeted disruption increases rifampin susceptibility and removes antibiotic-inactivating ability PMID:9371349.
The AMR mapping file records ARO:3000390 as a GO gap because GO:0003950 is a poly-ADP-ribosyltransferase term and protein-focused mono-ADP-ribosyltransferase terms do not fit a rifampin substrate [file:projects/ANTIMICROBIAL_RESISTANCE/aro2go.sssom.yaml]. The review proposes a new rifampin mono-ADP-ribosyltransferase activity term and adds only a broad interim GO:0016740 transferase candidate.