ArgA (Rv2747) is a short, approximately 19-kDa GNAT-family amino-acid N-acetyltransferase of Mycobacterium tuberculosis that acetylates L-glutamate and supplies N-acetylglutamate for L-arginine biosynthesis. Purified enzyme also acetylates L-glutamine, which was a better substrate in vitro, and is inhibited by L-arginine. Unlike classical two-domain bacterial N-acetylglutamate synthases, it lacks the extended N-terminal kinase-like region. Dimers and tetramers were observed in solution; efficient physiological glutamate turnover and any activating protein partner remain unresolved.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004042 L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor | IDA PMID:15838030 Functional characterization of a novel ArgA from Mycobacteri... | ACCEPT | Summary: Purified Rv2747 acetylates L-glutamate using acetyl-CoA. Reason: Direct target enzyme assays in PMID:15838030 establish glutamate-dependent turnover, corroborated by curated UniProt reaction chemistry. Glutamate did not saturate the enzyme at 600 mM; the reported sequential mechanism, full kinetic constants and NMR product confirmation used glutamine. Those limits do not negate the experimentally supported glutamate activity. Supporting Evidence: PMID:15838030 Although l -glutamate and l -glutamine served as substrates for Rv2747 file:MYCTU/argA/argA-uniprot.txt Reaction=L-glutamate + acetyl-CoA = N-acetyl-L-glutamate + CoA + H(+); |
| GO:0004042 L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor | IEA GO_REF:0000116 | ACCEPT | Summary: Purified Rv2747 acetylates L-glutamate using acetyl-CoA. Reason: Direct target enzyme assays in PMID:15838030 establish glutamate-dependent turnover, corroborated by curated UniProt reaction chemistry. Glutamate did not saturate the enzyme at 600 mM; the reported sequential mechanism, full kinetic constants and NMR product confirmation used glutamine. Those limits do not negate the experimentally supported glutamate activity. Supporting Evidence: PMID:15838030 Although l -glutamate and l -glutamine served as substrates for Rv2747 file:MYCTU/argA/argA-uniprot.txt Reaction=L-glutamate + acetyl-CoA = N-acetyl-L-glutamate + CoA + H(+); |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: A soluble cytoplasmic metabolic enzyme is the supported localization inference. Reason: PAINT node PTN001895129 supports conserved cytoplasmic activity, consistent with the soluble GNAT catalytic domain and intracellular arginine pathway. The primary biochemical paper is not direct native localization imaging; no chloroplast or mitochondrial location is transferred from family labels. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001895129 SUPPORTS TRANSFER Conserved cytoplasmic catalytic activity is compatible with a soluble bacterial biosynthetic enzyme. The inherited location is not a claim of native target imaging or plant organelle targeting. Supporting Evidence: file:MYCTU/argA/argA-uniprot.txt Belongs to the acetyltransferase family. PMID:15838030 Rv2747 encodes a much smaller, 19-kDa protein. |
| GO:0006526 L-arginine biosynthetic process | IDA PMID:15838030 Functional characterization of a novel ArgA from Mycobacteri... | ACCEPT | Summary: Rv2747 supplies the acetylated glutamate intermediate of arginine biosynthesis. Reason: The enzyme itself performs the initiating acetylation, rather than merely affecting arginine abundance. Primary15838030 supports this biochemical pathway assignment and arginine feedback inhibition. Native flux efficiency, possible glutamine-to-acetylglutamate conversion and a proposed activating partner are not directly established; the existing process annotation is retained without claiming those mechanisms. Supporting Evidence: PMID:15838030 catalyzes the initial step in l -arginine biosynthesis, namely the conversion of l -glutamate to Ξ±- N -acetyl- l -glutamate. |
| GO:0006526 L-arginine biosynthetic process | IEA GO_REF:0000041 | ACCEPT | Summary: Rv2747 supplies the acetylated glutamate intermediate of arginine biosynthesis. Reason: The enzyme itself performs the initiating acetylation, rather than merely affecting arginine abundance. Primary15838030 supports this biochemical pathway assignment and arginine feedback inhibition. Native flux efficiency, possible glutamine-to-acetylglutamate conversion and a proposed activating partner are not directly established; the existing process annotation is retained without claiming those mechanisms. Supporting Evidence: PMID:15838030 catalyzes the initial step in l -arginine biosynthesis, namely the conversion of l -glutamate to Ξ±- N -acetyl- l -glutamate. |
| GO:0008080 N-acetyltransferase activity | IBA GO_REF:0000033 | MODIFY | Summary: Refine the broad acyltransferase activity to the experimentally supported glutamate N-acetyltransferase reaction. Reason: The general activity is true, but the target has direct substrate-specific evidence for GO:0004042, already retained above. This refinement does not deny the separately observed glutamine activity; the enzyme is not asserted to be glutamate-exclusive. Propagation Review Root cause: TERM SCOPING PROBLEM Sources checked: PANTHER:PTN001895129 SUPPORTS TRANSFER The family node supports general N-acetyltransferase chemistry; direct Rv2747 biochemistry permits a more specific annotation without challenging the ancestral catalytic placement. Proposed replacements: L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor Supporting Evidence: PMID:15838030 Although l -glutamate and l -glutamine served as substrates for Rv2747 |
| GO:0008080 N-acetyltransferase activity | IEA GO_REF:0000002 | MODIFY | Summary: Refine the broad acyltransferase activity to the experimentally supported glutamate N-acetyltransferase reaction. Reason: The general activity is true, but the target has direct substrate-specific evidence for GO:0004042, already retained above. This refinement does not deny the separately observed glutamine activity; the enzyme is not asserted to be glutamate-exclusive. Proposed replacements: L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor Supporting Evidence: PMID:15838030 Although l -glutamate and l -glutamine served as substrates for Rv2747 |
| GO:0016747 acyltransferase activity, transferring groups other than amino-acyl groups | IEA GO_REF:0000002 | MODIFY | Summary: Refine the broad acyltransferase activity to the experimentally supported glutamate N-acetyltransferase reaction. Reason: The general activity is true, but the target has direct substrate-specific evidence for GO:0004042, already retained above. This refinement does not deny the separately observed glutamine activity; the enzyme is not asserted to be glutamate-exclusive. Proposed replacements: L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor Supporting Evidence: PMID:15838030 Although l -glutamate and l -glutamine served as substrates for Rv2747 |
| GO:0042803 protein homodimerization activity | IPI PMID:15838030 Functional characterization of a novel ArgA from Mycobacteri... | ACCEPT | Summary: Purified Rv2747 forms both dimers and tetramers in solution. Reason: Analytical gel filtration of the purified target detected equal amounts of dimer and tetramer (PMID:15838030). This directly supports the existing oligomerization annotation; it does not establish that one assembly is obligatory for catalysis or identify the dominant native cellular state. Supporting Evidence: PMID:15838030 the protein existed as a mixture of equal amounts of a dimer and a tetramer. |
| GO:0051289 protein homotetramerization | IPI PMID:15838030 Functional characterization of a novel ArgA from Mycobacteri... | ACCEPT | Summary: Purified Rv2747 forms both dimers and tetramers in solution. Reason: Analytical gel filtration of the purified target detected equal amounts of dimer and tetramer (PMID:15838030). This directly supports the existing oligomerization annotation; it does not establish that one assembly is obligatory for catalysis or identify the dominant native cellular state. Supporting Evidence: PMID:15838030 the protein existed as a mixture of equal amounts of a dimer and a tetramer. |
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Download this section (compressed HTML)Q: How does Rv2747 sustain physiological N-acetylglutamate production despite low apparent affinity for glutamate in vitro, and is an activating protein partner involved?
Q: Does its measured glutamine acetylation contribute to arginine synthesis in vivo through N-acetylglutamine deamidation?
Experiment: Compare glutamate and glutamine turnover and product identity for Rv2747 alone and with candidate native partners, then measure isotope flux into N-acetylglutamate in complemented conditional mutants.
Type: substrate kinetics, product analysis and native metabolic flux
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