arr encodes the Mycolicibacterium smegmatis rifampin ADP-ribosyltransferase Arr-1. Arr ribosylates rifampin, causing antibiotic inactivation and contributing substantially to intrinsic low susceptibility to rifampin in this organism. The current GO representation is missing from the fetched GOA file and GO lacks a substrate-specific rifampin mono-ADP-ribosyltransferase term.
Definition: Catalysis of the transfer of ADP-ribose to rifampin, producing a ribosylated rifampin derivative with reduced antibiotic activity.
Justification: Existing GO ADP-ribosyltransferase terms are protein- or poly-ADP-ribose focused and do not fit Arr, whose substrate is rifampin. The broad transferase term loses the antibiotic-inactivation mechanism.
Parent term: transferase activity
Mappings:
Supporting Evidence:
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0016740 transferase activity | RCA file:genes/MYCSM/arr/arr-uniprot.txt | NEW | Summary: NEW interim molecular-function annotation. UniProt carries only the broad transferase GO line, while the specific function is rifampin mono-ADP-ribosyltransferase activity. Reason: The GOA TSV fetched for this accession is empty, but the UniProt flat file contains a transferase GO cross-reference and CARD identifies Arr-1 as an antibiotic-inactivation determinant. A more specific GO term should be requested. Supporting Evidence: file:genes/MYCSM/arr/arr-uniprot.txt DE SubName: Full=Rifampin ADP-ribosyl transferase PMID:9371349 Mycobacterium smegmatis inactivates rifampin by ribosylating this antibiotic. |
| GO:0046677 response to antibiotic | RCA PMID:9371349 Ribosylative inactivation of rifampin by Mycobacterium smegm... | NEW | Summary: NEW high-level process annotation for Arr-mediated rifampin resistance. Reason: Arr directly inactivates rifampin and gene disruption increases rifampin susceptibility. The process term is high-level, but it is appropriate for this antibiotic-inactivation determinant. Supporting Evidence: PMID:9371349 Targeted disruption of the gene in M. smegmatis resulted in mutants with much increased susceptibility to rifampin file:genes/MYCSM/arr/arr-uniprot.txt DR CARD; ARO:3002846; arr-1; ARO:0001004; antibiotic inactivation. |
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Download this section (compressed HTML)Q: Should the Arr GO term be named for rifampin specifically, or for the broader rifamycin class if substrate evidence supports it?
Experiment: Purify Arr-1 and measure ADP-ribosylation of rifampin and related rifamycins by LC-MS to define the substrate range for a GO term.
Type: in vitro enzyme assay
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