aruC (PA0895) encodes the N2-succinylornithine / N2-acetylornithine 5-aminotransferase of Pseudomonas aeruginosa (SOAT/ACOAT, EC 2.6.1.81 and 2.6.1.11), a cytoplasmic, pyridoxal 5'-phosphate-dependent class-III aminotransferase of the ArgD subfamily. It is the first gene of the aruCFGDB operon of the arginine succinyltransferase (AST) pathway, the main route of aerobic arginine and ornithine utilization, where it transaminates N2-succinylornithine to N-succinylglutamate 5-semialdehyde with 2-oxoglutarate. The same enzyme transaminates N2-acetylornithine, the fourth step of arginine biosynthesis, and is thought to serve both pathways. Its synthesis is induced by arginine through the AraC-family regulator ArgR and is subject to catabolite repression by succinate and other carbon sources.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003992 N2-acetyl-L-ornithine:2-oxoglutarate 5-transaminase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000241318 (ArgD/AstC clade of PTHR11986), seeded by five experimentally characterised members including this gene. The target in its own WITH/FROM is expected. Reason: AruC is inside the clade that has this activity and its own ACOAT activity was measured on the purified enzyme, with a Km of 1.1 mM for acetylornithine. Supporting Evidence: file:PSEAE/aruC/aruC-uniprot.txt KM=1.1 mM for N(2)-acetyl-L-ornithine (at pH 9.0) |
| GO:0003992 N2-acetyl-L-ornithine:2-oxoglutarate 5-transaminase activity | IDA PMID:16593724 N-Succinylated intermediates in an arginine catabolic pathwa... | ACCEPT | Summary: PseudoCAP row from Jann et al. 1986; one of five seeds of the PTN000241318 ACOAT IBD. The paper uses purified N2-acetylornithine 5-aminotransferase. Reason: Sound. The purified P. aeruginosa ACOAT was assayed directly, and the activity is assignable to AruC (UniProt records both activities with kinetics from the cloned aru genes, PMID:9393691). Supporting Evidence: PMID:16593724 Purified N(2)-acetylornithine 5-aminotransferase (N(2)-acetyl-L-ornithine: 2-oxoglutarate aminotransferase, EC 2.6.1.11), an arginine biosynthetic enzyme, efficiently transaminated N(2)-succinylornithine PMID:238949 ACOAT from strain PAO 1 was purified over 40-fold to electrophoretic homogeneity. |
| GO:0003992 N2-acetyl-L-ornithine:2-oxoglutarate 5-transaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: HAMAP/EC/Rhea-based ACOAT activity. Reason: Same correct claim as the IBA and IDA rows. Supporting Evidence: file:PSEAE/aruC/aruC-uniprot.txt Reaction=N(2)-acetyl-L-ornithine + 2-oxoglutarate = N-acetyl-L-glutamate 5-semialdehyde + L-glutamate |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: HAMAP/UniProt cytoplasm location. Reason: AruC is a soluble PLP aminotransferase without signal peptide or transmembrane segments, acting on cytoplasmic pathway intermediates. Supporting Evidence: file:PSEAE/aruC/aruC-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005829 cytosol | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000241318, seeded by E. coli PatA (P42588). Reason: Bacterial cytoplasm is the cytosol for a soluble enzyme; consistent with the cytoplasm row and with the soluble class-III aminotransferase fold of the clade. Supporting Evidence: file:PSEAE/aruC/aruC-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0006520 amino acid metabolic process | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO from the Ac/SucOrn transaminase family (IPR017652). Reason: Correct but general. AruC acts in two specific arginine pathways, both already carried by the gene; list both descendants. Proposed replacements: L-arginine catabolic process L-arginine biosynthetic process Supporting Evidence: PMID:238949 P. aeruginosa this enzyme functions in the biosynthesis as well as in the catabolism of L-arginine. |
| GO:0006525 arginine metabolic process | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO from the AcOrn/SuccOrn aminotransferase family (IPR004636). Reason: Correct but general; both specific descendants (catabolism via the AST pathway and biosynthesis) are supported and already carried by the gene. Proposed replacements: L-arginine catabolic process L-arginine biosynthetic process Supporting Evidence: PMID:238949 P. aeruginosa this enzyme functions in the biosynthesis as well as in the catabolism of L-arginine. |
| GO:0006526 L-arginine biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000241318; the L-arginine biosynthesis IBD rests solely on this gene's PseudoCAP IDA row (35 leaf IBAs). Reason: For AruC the claim holds: it catalyses the ACOAT step, the fourth step of arginine biosynthesis, and the P. aeruginosa ACOAT was characterised as serving both biosynthesis and catabolism. Biosynthetic ArgD enzymes occur in every child clade of the node (tree checked 2026-11-05), so the term is the plesiomorphic state and the node is the right place for it. It does propagate to three scattered leaves whose names suggest other roles (two LysJ-type [LysW]-aminoadipate semialdehyde transaminases, a diaminobutyrate-pyruvate aminotransferase); that is flagged to PAINT and does not affect this gene. Supporting Evidence: PMID:238949 In Pseudomonas aeruginosa N-2-acetylornithine 5-aminotransferase (ACOAT), the fourth enzyme of arginine biosynthesis is induced about 15-fold file:PSEAE/aruC/aruC-uniprot.txt Amino-acid biosynthesis; L-arginine biosynthesis; N(2)-acetyl-L-ornithine from L-glutamate: step 4/4. |
| GO:0006526 L-arginine biosynthetic process | IDA PMID:16593724 N-Succinylated intermediates in an arginine catabolic pathwa... | ACCEPT | Summary: PseudoCAP row from Jann et al. 1986; sole seed of the PTN000241318 L-arginine biosynthesis IBD. Reason: Sound seed, with a caveat. The paper's experiments establish the catabolic pathway; its biosynthetic statement ("an arginine biosynthetic enzyme", "dual role") rests on the purified ACOAT's activity and on earlier work that purified PAO1 ACOAT as the fourth enzyme of arginine biosynthesis (PMID:238949). The enzyme catalyses the biosynthetic step, so it does part of the work of the process. No arginine-auxotrophy test of an aruC mutant was available to me, and PAO1 has an uncharacterised paralog in the same clade (PA0530), so whether AruC is the only biosynthetic ACOAT in vivo is open. Supporting Evidence: PMID:16593724 this explains the enzyme's dual role in arginine biosynthesis and catabolism PMID:238949 P. aeruginosa this enzyme functions in the biosynthesis as well as in the catabolism of L-arginine. |
| GO:0006526 L-arginine biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: HAMAP/UniPathway L-arginine biosynthesis (step 4/4 of N2-acetylornithine formation). Reason: Same claim as the IBA and IDA rows. Supporting Evidence: file:PSEAE/aruC/aruC-uniprot.txt Amino-acid biosynthesis; L-arginine biosynthesis; N(2)-acetyl-L-ornithine from L-glutamate: step 4/4. |
| GO:0006527 L-arginine catabolic process | IDA PMID:16593724 N-Succinylated intermediates in an arginine catabolic pathwa... | ACCEPT | Summary: PseudoCAP row from Jann et al. 1986, which established the arginine succinyltransferase catabolic pathway and showed that the purified aminotransferase transaminates its intermediate N2-succinylornithine. Reason: This is the paper's central finding and AruC's main physiological role: it is the SOAT of the AST pathway, encoded first in the aruCFGDB operon and induced by arginine. Supporting Evidence: PMID:16593724 Enzyme assays with crude P. aeruginosa extracts established the following pathway PMID:9393691 The aruCFGDB genes appear to form an operon transcribed from a promoter upstream of aruC |
| GO:0008483 transaminase activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO generic transaminase activity. Reason: Correct but general. Both specific transaminase activities are supported and already carried by the gene. Proposed replacements: succinylornithine:2-oxoglutarate transaminase activity N2-acetyl-L-ornithine:2-oxoglutarate 5-transaminase activity Supporting Evidence: file:PSEAE/aruC/aruC-uniprot.txt Transaminates both N(2)-acetylornithine and N(2)-succinylornithine. |
| GO:0030170 pyridoxal phosphate binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro2GO from the class-III aminotransferase domain. Reason: True: AruC is a PLP-dependent aminotransferase with the conserved PLP-binding lysine region. Cofactor binding is part of the transaminase activity rather than a separate function. Supporting Evidence: file:PSEAE/aruC/aruC-uniprot.txt Belongs to the class-III pyridoxal-phosphate-dependent |
| GO:0043825 succinylornithine:2-oxoglutarate transaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: EC/Rhea-based succinylornithine transaminase activity. Reason: The SOAT activity of AruC is experimentally established (purified enzyme, Km 1.4 mM for succinylornithine) and is its core catabolic activity. Supporting Evidence: file:PSEAE/aruC/aruC-uniprot.txt KM=1.4 mM for N(2)-succinyl-L-ornithine (at 15 mM 2-ketoglutarate and pH 9.0) PMID:16593724 an arginine biosynthetic enzyme, efficiently transaminated N(2)-succinylornithine |
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Download this section (compressed HTML)Q: Is a PAO1 aruC deletion an arginine auxotroph or bradytroph, or does the uncharacterised paralog PA0530 (same PAINT clade) provide ACOAT activity for arginine biosynthesis?
Q: Do the three non-ArgD leaves of PTN000241318 (PTN000241310 and PTN002633799, LysJ-type [LysW]-aminoadipate semialdehyde transaminases, and PTN000241321, a diaminobutyrate-pyruvate aminotransferase) retain acetylornithine aminotransferase activity, or should they carry NOT annotations for arginine biosynthesis? The tree offers no ArgD-only subnode to move the IBD to.
Experiment: Delete aruC and PA0530 singly and together in PAO1; test growth without arginine and on arginine as sole carbon source, and assay ACOAT and SOAT activities in extracts and with purified PA0530, to apportion the biosynthetic and catabolic roles.
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