Ornithine acetyltransferase (glutamate N-acetyltransferase, ArgJ family, EC 2.3.1.35) of Saccharomyces cerevisiae, a mitochondrial matrix enzyme that transfers the acetyl group from N2-acetyl-L-ornithine to L-glutamate, releasing L-ornithine and regenerating N-acetyl-L-glutamate. This is the fifth step of arginine biosynthesis and closes the cyclic (acetyl-recycling) route of ornithine synthesis. The precursor carries a short cleaved mitochondrial presequence and undergoes autoproteolytic internal cleavage before mitochondrial targeting into alpha and beta chains that form the active heterodimer. The enzyme is strongly inhibited by ornithine but largely insensitive to arginine. Arg7 also has a modest acetyl-CoA-dependent N-acetylglutamate synthase activity (EC 2.3.1.1): when overexpressed it can complement arg2 (NAGS) mutants. Deletion of ARG7 gives only a leaky arginine requirement, implying an alternative route from acetylornithine to ornithine.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004042 L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Acetyl-CoA-dependent N-acetylglutamate synthase activity propagated from PTN000559455, with ARG7 itself as experimental descendant. The activity is real but modest; the physiological N-acetylglutamate synthase is Arg2, and Arg7's main activity is acetyl transfer from acetylornithine. Supporting Evidence: PMID:9428669 The yeast enzyme is thus clearly, albeit modestly, bifunctional. |
| GO:0004042 L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor | IDA PMID:9428669 Characterization of the Saccharomyces cerevisiae ARG7 gene e... | KEEP AS NON CORE | Summary: Arg7p-linked acetylglutamate synthase activity was measurable in vitro and overexpressed ARG7 complements arg2 and E. coli argA mutants; the activity is genuine but modest and secondary to ornithine acetyltransferase activity. Supporting Evidence: PMID:9428669 The yeast enzyme is thus clearly, albeit modestly, bifunctional. PMID:9428669 overexpressed ARG7 can complement yeast arg2 and Escherichia coli argA mutations |
| GO:0004042 L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Automated UniRule/RHEA assignment of the minor acetyl-CoA-dependent activity; correct but secondary. Supporting Evidence: PMID:9428669 The yeast enzyme is thus clearly, albeit modestly, bifunctional. |
| GO:0004358 L-glutamate N-acetyltransferase activity, acting on acetyl-L-ornithine as donor | IEA GO_REF:0000120 | ACCEPT | Summary: Ornithine acetyltransferase (acetyl-L-ornithine:L-glutamate N-acetyltransferase) activity, the main catalytic function. Core function. Note that GOA lacks an experimental annotation for this MF although PMID:9428669 characterises it. Supporting Evidence: PMID:9428669 ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis file:yeast/ARG7/ARG7-uniprot.txt Reaction=N(2)-acetyl-L-ornithine + L-glutamate = N-acetyl-L-glutamate + L-ornithine; |
| GO:0004358 L-glutamate N-acetyltransferase activity, acting on acetyl-L-ornithine as donor | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways assignment of the ornithine acetyltransferase step; correct. Core function. Supporting Evidence: PMID:9428669 ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | ACCEPT | Summary: ARG7 has supported mitochondrial localization; the matrix assertion is retained separately. Reason: The curated HDA row derives from the PROMITO mitochondrial proteome. It establishes an organelle-level location; the general dataset quotation is not by itself a target-specific matrix assay. The root-organelle policy preserves mitochondrion as an informative claim. Matrix localization was checked and remains a separate annotation, with its own experimental or inference basis. Supporting Evidence: PMID:16823961 A total of 851 different proteins (PROMITO dataset) were identified |
| GO:0005739 mitochondrion | HDA PMID:24769239 Quantitative variations of the mitochondrial proteome and ph... | ACCEPT | Summary: ARG7 has supported mitochondrial localization; the matrix assertion is retained separately. Reason: The curated HDA row derives from quantitative proteomics of isolated yeast mitochondria. Retain the organelle observation without treating the study-wide quotation as direct matrix resolution. The root-organelle policy preserves mitochondrion as an informative claim. Matrix localization was checked and remains a separate annotation, with its own experimental or inference basis. Supporting Evidence: PMID:24769239 we performed an overall quantitative proteomic and phosphoproteomic study of isolated mitochondria |
| GO:0005759 mitochondrial matrix | IBA GO_REF:0000033 | ACCEPT | Summary: Mitochondrial matrix location; consistent with experiment. Supporting Evidence: file:yeast/ARG7/ARG7-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion matrix {ECO:0000255|HAMAP-Rule:MF_03124, ECO:0000269|PubMed:14576278}. PMID:9428669 We have cloned by functional complementation and characterized the yeast ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis. |
| GO:0005759 mitochondrial matrix | IDA PMID:205532 Arginine metabolism in Saccharomyces cerevisiae: subcellular... | ACCEPT | Summary: Fractionation associated acetylornithine-glutamate acetyltransferase with mitochondria. Supporting Evidence: PMID:205532 suggested that these enzymes were associated with the mitochondria |
| GO:0005759 mitochondrial matrix | IEA GO_REF:0000120 | ACCEPT | Summary: Mitochondrial matrix; correct. Supporting Evidence: file:yeast/ARG7/ARG7-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion matrix {ECO:0000255|HAMAP-Rule:MF_03124, ECO:0000269|PubMed:14576278}. PMID:9428669 We have cloned by functional complementation and characterized the yeast ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis. |
| GO:0005829 cytosol | RCA GO_REF:0000123 | MARK AS OVER ANNOTATED | Summary: The pathway-derived cytosol assignment over-states where the mature ornithine acetyltransferase acts; the active enzyme is mitochondrial, and the cytosolic stage is transient precursor processing. Reason: This RCA row derives from the SGD YeastPathways compartment assignment and uses the is_active_in qualifier, so it claims that the acetyltransferase acts in cytosol. Native fractionation places the acetylated-cycle enzymes, including ornithine acetyltransferase, in the mitochondrial particulate fraction (PMID:205532). PMID:10753950 shows that Arg7 autoproteolysis occurs before mitochondrial targeting, so a precursor pool transiently exists in cytosol, but leader-deletion and heterologous-expression experiments do not establish a steady-state native cytosolic acetyltransferase pool. The cytosol claim is therefore not entirely wrong for the precursor but over-annotates the site of activity. No NEW cytosolic annotation is proposed. Supporting Evidence: PMID:205532 These enzymes were exclusively particulate. Comparison with citrate synthase and cytochrome oxidase, and results from isopycnic gradient analysis, suggested that these enzymes were associated with the mitochondria. PMID:10753950 processing occurs before targeting to the mitochondria |
| GO:0006526 L-arginine biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: Automated pathway assignment; correct. Supporting Evidence: PMID:9428669 We have cloned by functional complementation and characterized the yeast ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis. |
| GO:0006526 L-arginine biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways assignment; correct. Supporting Evidence: PMID:9428669 We have cloned by functional complementation and characterized the yeast ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis. |
| GO:0006592 L-ornithine biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: Ornithine acetyltransferase releases L-ornithine; core process. Supporting Evidence: PMID:9428669 ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis PMID:9428669 While forming ornithine, this enzyme regenerates acetylglutamate |
| GO:0006592 L-ornithine biosynthetic process | IDA PMID:9428669 Characterization of the Saccharomyces cerevisiae ARG7 gene e... | ACCEPT | Summary: Arg7 catalyses formation of ornithine from acetylornithine. Supporting Evidence: PMID:9428669 ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis PMID:9428669 While forming ornithine, this enzyme regenerates acetylglutamate |
| GO:0008652 amino acid biosynthetic process | IEA GO_REF:0000117 | MODIFY | Summary: Very general ARBA-derived process term (amino acid / carboxylic acid biosynthesis). Correct but uninformative; the specific process is L-arginine biosynthesis, which is already annotated. Reason: Replace the grouping term with the specific pathway term. Proposed replacements: L-arginine biosynthetic process Supporting Evidence: PMID:9428669 We have cloned by functional complementation and characterized the yeast ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis. |
| GO:0046394 carboxylic acid biosynthetic process | IEA GO_REF:0000117 | MODIFY | Summary: Very general ARBA-derived process term (amino acid / carboxylic acid biosynthesis). Correct but uninformative; the specific process is L-arginine biosynthesis, which is already annotated. Reason: Replace the grouping term with the specific pathway term. Proposed replacements: L-arginine biosynthetic process Supporting Evidence: PMID:9428669 We have cloned by functional complementation and characterized the yeast ARG7 gene encoding mitochondrial ornithine acetyltransferase, the enzyme catalyzing the fifth step in arginine biosynthesis. |
| GO:0103045 L-methionine N-acyltransferase activity | RCA GO_REF:0000123 | MODIFY | Summary: The acetyl-cycle pathway assignment supports glutamate acetylation rather than a methionine-specific reaction. Reason: The proximate source is SGD_PWY:ARGSYNBSUB-PWY, the arginine acetyl-cycle pathway. Its initiating acetyl-transfer step uses L-glutamate. Target-specific work establishes acetyl-CoA-dependent N-acetylglutamate synthesis; replace this methionine-acceptor assignment with the existing GO:0004042. This is a pathway/reaction-specificity correction, not a claim that all possible side-substrate activities have been experimentally excluded. Proposed replacements: L-glutamate N-acetyltransferase activity, acting on acetyl-CoA as donor Supporting Evidence: PMID:9428669 Arg7p-linked acetylglutamate synthase activity was measurable in an assay. |
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