ArgJ (MJ0186) is the monofunctional ornithine acetyltransferase of Methanocaldococcus jannaschii, formerly Methanococcus jannaschii. It transfers the acetyl group from N-acetylornithine to glutamate, releasing ornithine and regenerating N-acetylglutamate in arginine biosynthesis. Purified enzyme and complementation experiments distinguish this recycling activity from acetyl-CoA-dependent pathway initiation, which this ArgJ does not perform. Its precursor is processed into alpha and beta chains that assemble as an alpha2beta2 enzyme.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004042 L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor | IBA GO_REF:0000033 | REMOVE | Summary: This specific initiation activity is directly contradicted for M. Reason: This specific initiation activity is directly contradicted for M. jannaschii ArgJ. PMID:10931207 reports that the archaeal gene rescues argE but not argA deficiency and that purified M. jannaschii enzyme only catalyzes acetylornithine recycling, whereas the bacterial comparator ArgJs additionally use acetyl-CoA. Thus a family-level initiation assignment must exclude this experimentally monofunctional member; this is not a donor-count or self-donor objection. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE Sources checked: PANTHER:PTN000559455 SUPPORTS SOURCE BUT NOT TARGET Acetyl-CoA-dependent initiation occurs in bifunctional bacterial ArgJ comparators, but direct complementation and purified-enzyme assays establish monofunctional recycling in MJ0186. The ancestral initiation assertion must not propagate to this experimentally distinguished member. Supporting Evidence: PMID:10931207 Archaeal argJ only complements an Escherichia coli argE mutant PMID:10931207 M. jannaschii ArgJ is therefore a monofunctional enzyme |
| GO:0004358 L-glutamate N-acetyltransferase activity, acting on acetyl-L-ornithine as donor | EXP PMID:10931207 Characterization and kinetic mechanism of mono- and bifuncti... | ACCEPT | Summary: The enzyme-specific activity is supported independently by curated reaction chemistry and target-specific experiments. Reason: The enzyme-specific activity is supported independently by curated reaction chemistry and target-specific experiments. Purified archaeal ArgJ recycles acetylornithine and complements argE deficiency; it does not use acetyl-CoA (PMID:10931207). Supporting Evidence: file:METJA/argJ/argJ-uniprot.txt Reaction=N(2)-acetyl-L-ornithine + L-glutamate = N-acetyl-L-glutamate + L-ornithine; Xref=Rhea:RHEA:15349, ChEBI:CHEBI:29985, ChEBI:CHEBI:44337, ChEBI:CHEBI:46911, ChEBI:CHEBI:57805; EC=2.3.1.35; Evidence={ECO:0000255|HAMAP-Rule:MF_01106, ECO:0000269|PubMed:10931207}; PMID:10931207 M. jannaschii ArgJ is therefore a monofunctional enzyme |
| GO:0004358 L-glutamate N-acetyltransferase activity, acting on acetyl-L-ornithine as donor | IEA GO_REF:0000120 | ACCEPT | Summary: The enzyme-specific activity is supported independently by curated reaction chemistry and target-specific experiments. Reason: The enzyme-specific activity is supported independently by curated reaction chemistry and target-specific experiments. Purified archaeal ArgJ recycles acetylornithine and complements argE deficiency; it does not use acetyl-CoA (PMID:10931207). Supporting Evidence: file:METJA/argJ/argJ-uniprot.txt Reaction=N(2)-acetyl-L-ornithine + L-glutamate = N-acetyl-L-glutamate + L-ornithine; Xref=Rhea:RHEA:15349, ChEBI:CHEBI:29985, ChEBI:CHEBI:44337, ChEBI:CHEBI:46911, ChEBI:CHEBI:57805; EC=2.3.1.35; Evidence={ECO:0000255|HAMAP-Rule:MF_01106, ECO:0000269|PubMed:10931207}; PMID:10931207 M. jannaschii ArgJ is therefore a monofunctional enzyme |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: The curated cytoplasmic localization is consistent with the soluble archaeal biosynthetic enzyme. Reason: The curated cytoplasmic localization is consistent with the soluble archaeal biosynthetic enzyme. Supporting Evidence: file:METJA/argJ/argJ-uniprot.txt Cytoplasm {ECO:0000255|HAMAP-Rule:MF_01106, ECO:0000305}. |
| GO:0006526 L-arginine biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: The protein directly catalyzes an acetylated-intermediate reaction that produces an arginine/ornithine precursor, so it participates in the biosynthetic process. Reason: The protein directly catalyzes an acetylated-intermediate reaction that produces an arginine/ornithine precursor, so it participates in the biosynthetic process. The ArgJ contribution is recycling, not de novo acetyl-CoA-dependent initiation. Supporting Evidence: file:METJA/argJ/argJ-uniprot.txt Reaction=N(2)-acetyl-L-ornithine + L-glutamate = N-acetyl-L-glutamate + L-ornithine; Xref=Rhea:RHEA:15349, ChEBI:CHEBI:29985, ChEBI:CHEBI:44337, ChEBI:CHEBI:46911, ChEBI:CHEBI:57805; EC=2.3.1.35; Evidence={ECO:0000255|HAMAP-Rule:MF_01106, ECO:0000269|PubMed:10931207}; PMID:10931207 M. jannaschii ArgJ is therefore a monofunctional enzyme file:METJA/argJ/argJ-uniprot.txt Amino-acid biosynthesis; L-arginine biosynthesis; L-ornithine and N-acetyl-L-glutamate from L-glutamate and N(2)-acetyl-L-ornithine (cyclic): step 1/1. {ECO:0000255|HAMAP-Rule:MF_01106}. |
| GO:0006592 L-ornithine biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: The protein directly catalyzes an acetylated-intermediate reaction that produces an arginine/ornithine precursor, so it participates in the biosynthetic process. Reason: The protein directly catalyzes an acetylated-intermediate reaction that produces an arginine/ornithine precursor, so it participates in the biosynthetic process. The ArgJ contribution is recycling, not de novo acetyl-CoA-dependent initiation. Supporting Evidence: file:METJA/argJ/argJ-uniprot.txt Reaction=N(2)-acetyl-L-ornithine + L-glutamate = N-acetyl-L-glutamate + L-ornithine; Xref=Rhea:RHEA:15349, ChEBI:CHEBI:29985, ChEBI:CHEBI:44337, ChEBI:CHEBI:46911, ChEBI:CHEBI:57805; EC=2.3.1.35; Evidence={ECO:0000255|HAMAP-Rule:MF_01106, ECO:0000269|PubMed:10931207}; PMID:10931207 M. jannaschii ArgJ is therefore a monofunctional enzyme file:METJA/argJ/argJ-uniprot.txt Amino-acid biosynthesis; L-arginine biosynthesis; L-ornithine and N-acetyl-L-glutamate from L-glutamate and N(2)-acetyl-L-ornithine (cyclic): step 1/1. {ECO:0000255|HAMAP-Rule:MF_01106}. |
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