DELTA-OAT is a mitochondrial pyridoxal-phosphate-dependent ornithine aminotransferase that converts ornithine to glutamate semialdehyde/P5C during arginine and ornithine degradation. It enables nitrogen recycling from these amino acids and contributes to P5C-dependent metabolic responses during non-host pathogen resistance. Its expression and activity respond to salinity in young seedlings, whereas native knockout studies do not support a major role in salt-induced proline synthesis.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004587 L-ornithine transaminase activity | IBA GO_REF:0000033 | ACCEPT | Summary: DELTA-OAT catalyzes ornithine delta-transamination to glutamate semialdehyde/P5C. Reason: Native knockout extracts lose almost all OAT activity (PMID:18419821), corroborating the original extract biochemistry (PMID:9576796), curated reaction, and inherited class-III aminotransferase function. This is free ornithine catabolism, not acetylornithine biosynthesis. Supporting Evidence: PMID:18419821 In oat1 and oat3 extracts, OAT activity was not significantly increased over control values and accounted for maximally 1/10 of the wildtype activity. file:ARATH/DELTA-OAT/DELTA-OAT-uniprot.txt Reaction=a 2-oxocarboxylate + L-ornithine = L-glutamate 5-semialdehyde |
| GO:0004587 L-ornithine transaminase activity | IDA PMID:9576796 Isolation of the ornithine-delta-aminotransferase cDNA and e... | ACCEPT | Summary: DELTA-OAT catalyzes ornithine delta-transamination to glutamate semialdehyde/P5C. Reason: Native knockout extracts lose almost all OAT activity (PMID:18419821), corroborating the original extract biochemistry (PMID:9576796), curated reaction, and inherited class-III aminotransferase function. This is free ornithine catabolism, not acetylornithine biosynthesis. Supporting Evidence: PMID:18419821 In oat1 and oat3 extracts, OAT activity was not significantly increased over control values and accounted for maximally 1/10 of the wildtype activity. file:ARATH/DELTA-OAT/DELTA-OAT-uniprot.txt Reaction=a 2-oxocarboxylate + L-ornithine = L-glutamate 5-semialdehyde |
| GO:0004587 L-ornithine transaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: DELTA-OAT catalyzes ornithine delta-transamination to glutamate semialdehyde/P5C. Reason: Native knockout extracts lose almost all OAT activity (PMID:18419821), corroborating the original extract biochemistry (PMID:9576796), curated reaction, and inherited class-III aminotransferase function. This is free ornithine catabolism, not acetylornithine biosynthesis. Supporting Evidence: PMID:18419821 In oat1 and oat3 extracts, OAT activity was not significantly increased over control values and accounted for maximally 1/10 of the wildtype activity. file:ARATH/DELTA-OAT/DELTA-OAT-uniprot.txt Reaction=a 2-oxocarboxylate + L-ornithine = L-glutamate 5-semialdehyde |
| GO:0004587 L-ornithine transaminase activity | IMP PMID:18419821 Ornithine-delta-aminotransferase is essential for arginine c... | ACCEPT | Summary: DELTA-OAT catalyzes ornithine delta-transamination to glutamate semialdehyde/P5C. Reason: Native knockout extracts lose almost all OAT activity (PMID:18419821), corroborating the original extract biochemistry (PMID:9576796), curated reaction, and inherited class-III aminotransferase function. This is free ornithine catabolism, not acetylornithine biosynthesis. Supporting Evidence: PMID:18419821 In oat1 and oat3 extracts, OAT activity was not significantly increased over control values and accounted for maximally 1/10 of the wildtype activity. file:ARATH/DELTA-OAT/DELTA-OAT-uniprot.txt Reaction=a 2-oxocarboxylate + L-ornithine = L-glutamate 5-semialdehyde |
| GO:0004587 L-ornithine transaminase activity | ISS PMID:9576796 Isolation of the ornithine-delta-aminotransferase cDNA and e... | ACCEPT | Summary: DELTA-OAT catalyzes ornithine delta-transamination to glutamate semialdehyde/P5C. Reason: Native knockout extracts lose almost all OAT activity (PMID:18419821), corroborating the original extract biochemistry (PMID:9576796), curated reaction, and inherited class-III aminotransferase function. This is free ornithine catabolism, not acetylornithine biosynthesis. Supporting Evidence: PMID:18419821 In oat1 and oat3 extracts, OAT activity was not significantly increased over control values and accounted for maximally 1/10 of the wildtype activity. file:ARATH/DELTA-OAT/DELTA-OAT-uniprot.txt Reaction=a 2-oxocarboxylate + L-ornithine = L-glutamate 5-semialdehyde |
| GO:0005739 mitochondrion | IBA GO_REF:0000033 | ACCEPT | Summary: Mitochondrial residence is a supported core localization. Reason: Full-length Arabidopsis OAT-GFP colocalizes with MitoTracker in protoplasts (PMID:18419821), directly establishing mitochondrial residence. Retain this informative organelle assertion alongside the existing curated matrix location; the imaging experiment itself does not resolve submitochondrial topology. The inherited organelle claim agrees with independent target evidence; no ancestral-node placement defect is established or inferred from its breadth. Supporting Evidence: PMID:18419821 colocalisation of the GFP-signal with the orange fluorescence of MitoTracker clearly identified the Ξ΄OAT-GFP containing compartments as mitochondria file:ARATH/DELTA-OAT/DELTA-OAT-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion matrix |
| GO:0005739 mitochondrion | IDA PMID:18419821 Ornithine-delta-aminotransferase is essential for arginine c... | ACCEPT | Summary: Mitochondrial residence is a supported core localization. Reason: Full-length Arabidopsis OAT-GFP colocalizes with MitoTracker in protoplasts (PMID:18419821), directly establishing mitochondrial residence. Retain this informative organelle assertion alongside the existing curated matrix location; the imaging experiment itself does not resolve submitochondrial topology. Supporting Evidence: PMID:18419821 colocalisation of the GFP-signal with the orange fluorescence of MitoTracker clearly identified the Ξ΄OAT-GFP containing compartments as mitochondria file:ARATH/DELTA-OAT/DELTA-OAT-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion matrix |
| GO:0005759 mitochondrial matrix | IEA GO_REF:0000044 | ACCEPT | Summary: Mitochondrial matrix is the principal catabolic compartment. Reason: Native GFP targeting and nitrogen-source phenotypes place OAT in the mitochondrial degradation route; the matrix assignment is curated in UniProt, with imaging establishing mitochondria rather than resolving the matrix separately. Supporting Evidence: PMID:18419821 colocalisation of the GFP-signal with the orange fluorescence of MitoTracker clearly identified the Ξ΄OAT-GFP containing compartments as mitochondria file:ARATH/DELTA-OAT/DELTA-OAT-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion matrix |
| GO:0006527 L-arginine catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: OAT executes ornithine breakdown and the downstream ornithine branch of arginine degradation. Reason: Two null mutants fail to utilize Arg or Orn as nitrogen sources, accumulate pathway intermediates, and are complemented by OAT-GFP. This establishes catabolic participation, not merely a consequence of altered amino-acid pools. Supporting Evidence: PMID:18419821 These findings demonstrated that oat mutants could not use Arg or Orn as nitrogen sources for growth. |
| GO:0006527 L-arginine catabolic process | IMP PMID:18419821 Ornithine-delta-aminotransferase is essential for arginine c... | ACCEPT | Summary: OAT executes ornithine breakdown and the downstream ornithine branch of arginine degradation. Reason: Two null mutants fail to utilize Arg or Orn as nitrogen sources, accumulate pathway intermediates, and are complemented by OAT-GFP. This establishes catabolic participation, not merely a consequence of altered amino-acid pools. Supporting Evidence: PMID:18419821 These findings demonstrated that oat mutants could not use Arg or Orn as nitrogen sources for growth. |
| GO:0006593 L-ornithine catabolic process | IDA PMID:9576796 Isolation of the ornithine-delta-aminotransferase cDNA and e... | ACCEPT | Summary: OAT executes ornithine breakdown and the downstream ornithine branch of arginine degradation. Reason: Two null mutants fail to utilize Arg or Orn as nitrogen sources, accumulate pathway intermediates, and are complemented by OAT-GFP. This establishes catabolic participation, not merely a consequence of altered amino-acid pools. Supporting Evidence: PMID:18419821 These findings demonstrated that oat mutants could not use Arg or Orn as nitrogen sources for growth. |
| GO:0006593 L-ornithine catabolic process | IMP PMID:18419821 Ornithine-delta-aminotransferase is essential for arginine c... | ACCEPT | Summary: OAT executes ornithine breakdown and the downstream ornithine branch of arginine degradation. Reason: Two null mutants fail to utilize Arg or Orn as nitrogen sources, accumulate pathway intermediates, and are complemented by OAT-GFP. This establishes catabolic participation, not merely a consequence of altered amino-acid pools. Supporting Evidence: PMID:18419821 These findings demonstrated that oat mutants could not use Arg or Orn as nitrogen sources for growth. |
| GO:0008270 zinc ion binding | HDA PMID:20018591 Divalent metal ions in plant mitochondria and their role in ... | UNDECIDED | Summary: The metal-affinity screen suggests association, but target-specific direct binding remains unresolved. Reason: Full PMID:20018591 uses metal-loaded IMAC on mitochondrial extracts and identifies multiple proteins from enriched gel bands. This does not make metal binding false or require a physiological cofactor role; however, the exact target rows in supplemental S3/S4 could not be recovered, and direct binding versus co-purification is unresolved. Preserve the experimental annotation pending target-specific evidence rather than replacing it with the enzyme cofactor. Supporting Evidence: PMID:20018591 The interaction of metal ions with mitochondrial proteins that might be responsible for these toxic effects was investigated in vitro using IMAC to trap metal-binding proteins. |
| GO:0009507 chloroplast | ISM GO_REF:0000122 | UNDECIDED | Summary: An additional plastid pool is unresolved. Reason: Direct full-length GFP evidence supports mitochondria. The PMID:28887381 supplemental S1 target row lists mitochondrion and detects OAT in mixed fractions; it does not independently establish plastid import. The AtSubP prediction and proteomic annotation are preserved, but neither absence of a plastid assay nor mitochondrial targeting proves that dual localization is impossible. Supporting Evidence: PMID:18419821 colocalisation of the GFP-signal with the orange fluorescence of MitoTracker clearly identified the Ξ΄OAT-GFP containing compartments as mitochondria file:ARATH/DELTA-OAT/DELTA-OAT-source-analysis/README.md The S1 Mapp sheet lists all four target proteins as mitochondrion. |
| GO:0009536 plastid | HDA PMID:28887381 Global Analysis of Membrane-associated Protein Oligomerizati... | UNDECIDED | Summary: An additional plastid pool is unresolved. Reason: Direct full-length GFP evidence supports mitochondria. The PMID:28887381 supplemental S1 target row lists mitochondrion and detects OAT in mixed fractions; it does not independently establish plastid import. The AtSubP prediction and proteomic annotation are preserved, but neither absence of a plastid assay nor mitochondrial targeting proves that dual localization is impossible. Supporting Evidence: PMID:18419821 colocalisation of the GFP-signal with the orange fluorescence of MitoTracker clearly identified the Ξ΄OAT-GFP containing compartments as mitochondria file:ARATH/DELTA-OAT/DELTA-OAT-source-analysis/README.md The S1 Mapp sheet lists all four target proteins as mitochondrion. |
| GO:0009626 plant-type hypersensitive response | TAS PMID:22321246 Ornithine-delta-aminotransferase and proline dehydrogenase g... | KEEP AS NON CORE | Summary: OAT contributes to non-host bacterial resistance and the associated hypersensitive response. Reason: The target Arabidopsis mutant evidence in PMID:22321246 links altered P5C metabolism to diminished pathogen-induced ROS and compromised resistance; Nicotiana silencing supplies complementary evidence. Retain this contextual defense role without claiming that OAT directly synthesizes ROS or operates as an immune receptor. Supporting Evidence: PMID:22321246 Arabidopsis mutants for these genes compromised non-host resistance and showed a decrease in non-host pathogen-induced ROS. |
| GO:0009651 response to salt stress | IDA PMID:9576796 Isolation of the ornithine-delta-aminotransferase cDNA and e... | KEEP AS NON CORE | Summary: OAT expression and extract activity respond to salinity in young plantlets. Reason: PMID:9576796 directly observes age-dependent salt-induced expression and activity; the adult response is weaker. Response to a stimulus does not require a knockout fitness defect. The later null-mutant experiment rules against a major contribution to stress-induced proline accumulation under its conditions, not against the measured biochemical response. Supporting Evidence: PMID:9576796 In young plantlets, free Pro content, Delta1-pyrroline-5-carboxylate synthase mRNA, delta-OAT activity, and delta-OAT mRNA were all increased by salt-stress treatment. PMID:18419821 These findings indicate that Ξ΄OAT does not contribute significantly to stress-induced Pro biosynthesis in vivo during salt stress. |
| GO:0030170 pyridoxal phosphate binding | IEA GO_REF:0000002 | ACCEPT | Summary: OAT is a PLP-dependent aminotransferase. Reason: The class-III aminotransferase classification and conserved curated cofactor site support PLP binding as a core catalytic property; this is independent of its salt-response phenotype. Supporting Evidence: file:ARATH/DELTA-OAT/DELTA-OAT-uniprot.txt SIMILARITY: Belongs to the class-III pyridoxal-phosphate-dependent CC aminotransferase family. |
| GO:0042538 hyperosmotic salinity response | IDA PMID:9576796 Isolation of the ornithine-delta-aminotransferase cDNA and e... | KEEP AS NON CORE | Summary: OAT expression and extract activity respond to salinity in young plantlets. Reason: PMID:9576796 directly observes age-dependent salt-induced expression and activity; the adult response is weaker. Response to a stimulus does not require a knockout fitness defect. The later null-mutant experiment rules against a major contribution to stress-induced proline accumulation under its conditions, not against the measured biochemical response. Supporting Evidence: PMID:9576796 In young plantlets, free Pro content, Delta1-pyrroline-5-carboxylate synthase mRNA, delta-OAT activity, and delta-OAT mRNA were all increased by salt-stress treatment. PMID:18419821 These findings indicate that Ξ΄OAT does not contribute significantly to stress-induced Pro biosynthesis in vivo during salt stress. |
| GO:0042742 defense response to bacterium | IEP PMID:22321246 Ornithine-delta-aminotransferase and proline dehydrogenase g... | KEEP AS NON CORE | Summary: OAT contributes to non-host bacterial resistance and the associated hypersensitive response. Reason: The target Arabidopsis mutant evidence in PMID:22321246 links altered P5C metabolism to diminished pathogen-induced ROS and compromised resistance; Nicotiana silencing supplies complementary evidence. Retain this contextual defense role without claiming that OAT directly synthesizes ROS or operates as an immune receptor. Supporting Evidence: PMID:22321246 Arabidopsis mutants for these genes compromised non-host resistance and showed a decrease in non-host pathogen-induced ROS. |
| GO:0051646 mitochondrion localization | IDA PMID:18419821 Ornithine-delta-aminotransferase is essential for arginine c... | REMOVE | Summary: The experiment localizes OAT protein, not mitochondria within the cell. Reason: The current GO:0051646 definition concerns transport or maintenance of mitochondria at cellular positions. Full PMID:18419821 images OAT-GFP import and tests catabolism; it does not show OAT performing organelle positioning. Mitochondrial residence is retained separately as cellular-component annotations. Supporting Evidence: PMID:18419821 colocalisation of the GFP-signal with the orange fluorescence of MitoTracker clearly identified the Ξ΄OAT-GFP containing compartments as mitochondria |
| GO:0055129 L-proline biosynthetic process | IDA PMID:9576796 Isolation of the ornithine-delta-aminotransferase cDNA and e... | REMOVE | Summary: The early inference of native proline synthesis was superseded by direct loss-of-function tests. Reason: Full PMID:9576796 links coincident OAT activity/transcript and proline increases after salt, without demonstrating OAT-dependent flux into proline. Full PMID:18419821 then tests that inference using two null mutants and finds normal proline accumulation while demonstrating defective Arg/Orn catabolism. Retain the source measurements and salt-response rows, but reject the positive physiological biosynthesis claim rather than simultaneously accepting it and the NOT annotation. Supporting Evidence: PMID:9576796 In young plantlets, free Pro content, Delta1-pyrroline-5-carboxylate synthase mRNA, delta-OAT activity, and delta-OAT mRNA were all increased by salt-stress treatment. PMID:18419821 These findings indicate that Ξ΄OAT does not contribute significantly to stress-induced Pro biosynthesis in vivo during salt stress. |
| GO:0055129 L-proline biosynthetic process | IMP NOT PMID:18419821 Ornithine-delta-aminotransferase is essential for arginine c... | ACCEPT | Summary: Retain the explicit NOT annotation for native proline biosynthesis in the tested conditions. Reason: Full PMID:18419821 shows unchanged basal and salt-induced proline accumulation in two null lines despite loss of OAT activity, plus mitochondrial catabolic targeting. This negative result concerns the tested Arabidopsis physiological role, not the chemical impossibility of converting ornithine-derived carbon into proline in every engineered or nutritional context. Supporting Evidence: PMID:18419821 These findings indicate that Ξ΄OAT does not contribute significantly to stress-induced Pro biosynthesis in vivo during salt stress. |
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Download this section (compressed HTML)Q: Does a condition-specific plastid pool exist beyond the well-supported mitochondrial enzyme?
Q: How does OAT-derived P5C influence non-host resistance without driving the principal stress-induced proline synthesis route?
Experiment: Combine endogenous tagging with organelle fractionation controls and isotope-labeled substrate/product measurements in single and complemented mutants to distinguish compartment-specific enzyme pools and pathway flux.
Type: native localization and isotope flux
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