ARGAH1 is a manganese-dependent arginase/agmatinase that hydrolyzes arginine to ornithine and urea and can hydrolyze agmatine to putrescine. It forms a homohexamer with contributions from neighboring subunits to substrate recognition. A mitochondrial matrix pool supports amino-acid nitrogen mobilization; its tissue expression differs from ARGAH2, including detectable pollen enzyme activity. Its agmatinase capacity has been demonstrated by heterologous complementation, while the relative endogenous flux through the two reactions remains context dependent.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000050 urea cycle | IEA GO_REF:0000041 | KEEP AS NON CORE | Summary: Arginase supplies the arginine-cleavage arm of ornithine/arginine recycling. Reason: The current GO urea-cycle definition does not require ureotelic nitrogen excretion. Arginase chemistry plus the native ornithine/citrulline/arginine recycling observed in OAT mutants supports a contextual cycle annotation. Catabolic nitrogen mobilization is the core function; this does not assert mammalian hepatic detoxification or a quantitatively demonstrated closed cycle in every tissue. Supporting Evidence: PMID:18419821 Accumulation of Cit indicated that Orn and Arg were metabolised after uptake, most likely by enzymes of the urea cycle. file:ARATH/ARGAH1/ARGAH1-uniprot.txt Reaction=L-arginine + H2O = urea + L-ornithine; |
| GO:0000287 magnesium ion binding | IDA PMID:32754173 The Neighboring Subunit Is Engaged to Stabilize the Substrat... | MODIFY | Summary: The reported structural cofactor is manganese, not magnesium. Reason: The complete PMID:32754173 crystal/SAXS study identifies a binuclear Mn center in AtARGAH1. MgCl2 occurs as a Medicago crystallization reagent, not as a bound Arabidopsis catalytic metal. Correct the ion identity to manganese without claiming that all possible Mg association has been experimentally excluded. Proposed replacements: manganese ion binding Supporting Evidence: PMID:32754173 The active site with a double manganese cluster is formed in each ARGAH subunit |
| GO:0004053 arginase activity | IBA GO_REF:0000033 | ACCEPT | Summary: ARGAH hydrolyzes arginine to ornithine and urea. Reason: Native pollen activity, argah loss-of-function enzyme assays and the AtARGAH1 product-bound structure corroborate the original yeast-complementation annotation. The 1995 cache has bibliographic text only, so this action rests on independently inspected later primary evidence as well. Supporting Evidence: PMID:18425591 We demonstrated tissue-specific transcript expression and enzyme activity in pollen for ARGAH1, but not ARGAH2. PMID:32754173 The active site with a double manganese cluster is formed in each ARGAH subunit |
| GO:0004053 arginase activity | IEA GO_REF:0000120 | ACCEPT | Summary: ARGAH hydrolyzes arginine to ornithine and urea. Reason: Native pollen activity, argah loss-of-function enzyme assays and the AtARGAH1 product-bound structure corroborate the original yeast-complementation annotation. The 1995 cache has bibliographic text only, so this action rests on independently inspected later primary evidence as well. Supporting Evidence: PMID:18425591 We demonstrated tissue-specific transcript expression and enzyme activity in pollen for ARGAH1, but not ARGAH2. PMID:32754173 The active site with a double manganese cluster is formed in each ARGAH subunit |
| GO:0004053 arginase activity | IGI PMID:7770544 Nucleotide sequence of Arabidopsis thaliana arginase express... | ACCEPT | Summary: ARGAH hydrolyzes arginine to ornithine and urea. Reason: Native pollen activity, argah loss-of-function enzyme assays and the AtARGAH1 product-bound structure corroborate the original yeast-complementation annotation. The 1995 cache has bibliographic text only, so this action rests on independently inspected later primary evidence as well. Supporting Evidence: PMID:18425591 We demonstrated tissue-specific transcript expression and enzyme activity in pollen for ARGAH1, but not ARGAH2. PMID:32754173 The active site with a double manganese cluster is formed in each ARGAH subunit |
| GO:0004053 arginase activity | IMP PMID:18425591 Analysis of Arabidopsis arginase gene transcription patterns... | ACCEPT | Summary: ARGAH hydrolyzes arginine to ornithine and urea. Reason: Native pollen activity, argah loss-of-function enzyme assays and the AtARGAH1 product-bound structure corroborate the original yeast-complementation annotation. The 1995 cache has bibliographic text only, so this action rests on independently inspected later primary evidence as well. Supporting Evidence: PMID:18425591 We demonstrated tissue-specific transcript expression and enzyme activity in pollen for ARGAH1, but not ARGAH2. PMID:32754173 The active site with a double manganese cluster is formed in each ARGAH subunit |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | ACCEPT | Summary: Mitochondrial residence is a supported core localization. Reason: The target Arabidopsis ARGAH1 construct colocalizes with a mitochondrial matrix marker in tobacco BY-2 cells, and selective permeabilization supports an internal mitochondrial pool (PMID:18567826). This establishes mitochondrial residence while the more specific matrix location is added separately. It does not exclude a distinct chloroplast pool under other conditions. Independent target localization supports the transferred organelle claim without treating the computational row as a new direct experiment. Supporting Evidence: file:ARATH/ARGAH1/ARGAH1-source-analysis/README.md Therefore, each protein was actually localized in the mitochondrial interior (matrix) |
| GO:0005739 mitochondrion | ISM GO_REF:0000122 | ACCEPT | Summary: Mitochondrial residence is a supported core localization. Reason: The target Arabidopsis ARGAH1 construct colocalizes with a mitochondrial matrix marker in tobacco BY-2 cells, and selective permeabilization supports an internal mitochondrial pool (PMID:18567826). This establishes mitochondrial residence while the more specific matrix location is added separately. It does not exclude a distinct chloroplast pool under other conditions. Independent target localization supports the transferred organelle claim without treating the computational row as a new direct experiment. Supporting Evidence: file:ARATH/ARGAH1/ARGAH1-source-analysis/README.md Therefore, each protein was actually localized in the mitochondrial interior (matrix) |
| GO:0005829 cytosol | HDA PMID:28887381 Global Analysis of Membrane-associated Protein Oligomerizati... | UNDECIDED | Summary: Cytosolic residence is unresolved despite detection in proteomic fractions. Reason: The PMID:28887381 S1 target entry uses a mitochondrial location assignment; fraction recovery and the study-wide cytosolic classification do not by themselves resolve a native cytosolic pool versus released organellar enzyme. The independently demonstrated matrix pool does not rule out a second pool, so the HDA annotation remains open. Supporting Evidence: file:ARATH/ARGAH1/ARGAH1-source-analysis/README.md Therefore, each protein was actually localized in the mitochondrial interior (matrix) file:ARATH/DELTA-OAT/DELTA-OAT-source-analysis/README.md The S1 Mapp sheet lists all four target proteins as mitochondrion. |
| GO:0006527 L-arginine catabolic process | IGI PMID:7770544 Nucleotide sequence of Arabidopsis thaliana arginase express... | ACCEPT | Summary: ARGAH1 performs the entry hydrolysis step in arginine catabolism. Reason: The curated reaction, complementation and native mutant enzyme measurements establish an enzyme that performs the degradation step. Its comparatively minor seedling contribution does not mean absence of catalytic participation. Supporting Evidence: file:ARATH/ARGAH1/ARGAH1-uniprot.txt Reaction=L-arginine + H2O = urea + L-ornithine; file:ARATH/ARGAH1/ARGAH1-source-analysis/README.md T-DNA disruption mutant argah1-1 |
| GO:0008783 agmatinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: ARGAH also catalyzes agmatine hydrolysis to putrescine. Reason: PMID:28716421 provides target-specific functional evidence, not merely an arginase/agmatinase family name. Both paralogs rescue ODC-deficient yeast together with ADC2; purified coupled assays specifically examine ARGAH2. ARGAH1 activity is therefore supported by complementation, not assigned ARGAH2 kinetic parameters. Supporting Evidence: PMID:28716421 Transformation of Arabidopsis thaliana ADC2, and any of the arginases from A. thaliana (ARGAH1, or ARGHA2) or the soybean gene Glyma.03g028000 (GmARGAH) into a yeast strain deficient in ODC, fully complemented the mutant phenotype. |
| GO:0008783 agmatinase activity | IDA PMID:28716421 Dual functioning of plant arginases provides a third route f... | ACCEPT | Summary: ARGAH also catalyzes agmatine hydrolysis to putrescine. Reason: PMID:28716421 provides target-specific functional evidence, not merely an arginase/agmatinase family name. Both paralogs rescue ODC-deficient yeast together with ADC2; purified coupled assays specifically examine ARGAH2. ARGAH1 activity is therefore supported by complementation, not assigned ARGAH2 kinetic parameters. Supporting Evidence: PMID:28716421 Transformation of Arabidopsis thaliana ADC2, and any of the arginases from A. thaliana (ARGAH1, or ARGHA2) or the soybean gene Glyma.03g028000 (GmARGAH) into a yeast strain deficient in ODC, fully complemented the mutant phenotype. |
| GO:0008783 agmatinase activity | IEA GO_REF:0000120 | ACCEPT | Summary: ARGAH also catalyzes agmatine hydrolysis to putrescine. Reason: PMID:28716421 provides target-specific functional evidence, not merely an arginase/agmatinase family name. Both paralogs rescue ODC-deficient yeast together with ADC2; purified coupled assays specifically examine ARGAH2. ARGAH1 activity is therefore supported by complementation, not assigned ARGAH2 kinetic parameters. Supporting Evidence: PMID:28716421 Transformation of Arabidopsis thaliana ADC2, and any of the arginases from A. thaliana (ARGAH1, or ARGHA2) or the soybean gene Glyma.03g028000 (GmARGAH) into a yeast strain deficient in ODC, fully complemented the mutant phenotype. |
| GO:0009446 putrescine biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: The agmatinase reaction directly supplies putrescine. Reason: Both Arabidopsis paralogs support an ADC-dependent route in yeast, and purified ARGAH2 has direct coupled biochemical support. This establishes synthetic capacity, while its fractional contribution to endogenous plant putrescine flux and stress-dependent dominance remain unresolved. The older simultaneous-silencing study is corroborative metabolic context, not proof that every tissue depends on this route. Supporting Evidence: PMID:28716421 Transformation of Arabidopsis thaliana ADC2, and any of the arginases from A. thaliana (ARGAH1, or ARGHA2) or the soybean gene Glyma.03g028000 (GmARGAH) into a yeast strain deficient in ODC, fully complemented the mutant phenotype. |
| GO:0009446 putrescine biosynthetic process | IDA PMID:28716421 Dual functioning of plant arginases provides a third route f... | ACCEPT | Summary: The agmatinase reaction directly supplies putrescine. Reason: Both Arabidopsis paralogs support an ADC-dependent route in yeast, and purified ARGAH2 has direct coupled biochemical support. This establishes synthetic capacity, while its fractional contribution to endogenous plant putrescine flux and stress-dependent dominance remain unresolved. The older simultaneous-silencing study is corroborative metabolic context, not proof that every tissue depends on this route. Supporting Evidence: PMID:28716421 Transformation of Arabidopsis thaliana ADC2, and any of the arginases from A. thaliana (ARGAH1, or ARGHA2) or the soybean gene Glyma.03g028000 (GmARGAH) into a yeast strain deficient in ODC, fully complemented the mutant phenotype. |
| GO:0009446 putrescine biosynthetic process | IEA GO_REF:0000117 | ACCEPT | Summary: The agmatinase reaction directly supplies putrescine. Reason: Both Arabidopsis paralogs support an ADC-dependent route in yeast, and purified ARGAH2 has direct coupled biochemical support. This establishes synthetic capacity, while its fractional contribution to endogenous plant putrescine flux and stress-dependent dominance remain unresolved. The older simultaneous-silencing study is corroborative metabolic context, not proof that every tissue depends on this route. Supporting Evidence: PMID:28716421 Transformation of Arabidopsis thaliana ADC2, and any of the arginases from A. thaliana (ARGAH1, or ARGHA2) or the soybean gene Glyma.03g028000 (GmARGAH) into a yeast strain deficient in ODC, fully complemented the mutant phenotype. |
| GO:0016813 hydrolase activity, acting on carbon-nitrogen (but not peptide) bonds, in linear amidines | IEA GO_REF:0000002 | MODIFY | Summary: Refine amidinohydrolase activity to the two supported substrate-specific activities. Reason: Arginine and agmatine hydrolysis are independently supported; retaining only the superclass would hide the demonstrated dual specificity. Proposed replacements: arginase activity agmatinase activity Supporting Evidence: PMID:28716421 Transformation of Arabidopsis thaliana ADC2, and any of the arginases from A. thaliana (ARGAH1, or ARGHA2) or the soybean gene Glyma.03g028000 (GmARGAH) into a yeast strain deficient in ODC, fully complemented the mutant phenotype. file:ARATH/ARGAH1/ARGAH1-uniprot.txt Reaction=L-arginine + H2O = urea + L-ornithine; |
| GO:0034214 protein hexamerization | IDA PMID:32754173 The Neighboring Subunit Is Engaged to Stabilize the Substrat... | ACCEPT | Summary: ARGAH1 forms a functional homohexamer. Reason: Full PMID:32754173 establishes the hexamer by crystallography and solution SAXS; neighboring-subunit residues contribute to substrate recognition. This is a core assembly property rather than an incidental interaction. Supporting Evidence: PMID:32754173 The estimated molecular weight of AtARGAH1 from SAXS data (211 kDa) matches almost ideally the hexameric AtARGAH1 |
| GO:0046872 metal ion binding | IEA GO_REF:0000002 | MODIFY | Summary: Refine generic metal binding to the catalytic manganese cofactor. Reason: Direct AtARGAH1 structures and conserved curated Mn-binding residues in ARGAH2 support this specificity. Cobalt-affinity screen annotations remain separately unresolved and do not establish a physiological cobalt cofactor. Proposed replacements: manganese ion binding Supporting Evidence: PMID:32754173 The active site with a double manganese cluster is formed in each ARGAH subunit |
| GO:0050897 cobalt 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:0005759 mitochondrial matrix | IDA PMID:18567826 Arginase-negative mutants of Arabidopsis exhibit increased n... | NEW | Summary: The tagged Arabidopsis arginase is experimentally localized to the mitochondrial matrix in tobacco BY-2 cells. Reason: The target-protein construct colocalizes with the E1Ξ² matrix marker and is inaccessible to anti-myc antibody after selective plasma-membrane permeabilization with digitonin. Together these identify the mitochondrial interior. Add the subcompartment alongside retained mitochondrial organelle rows, without claiming native Arabidopsis fractionation or excluding other pools. Supporting Evidence: file:ARATH/ARGAH1/ARGAH1-source-analysis/README.md Therefore, each protein was actually localized in the mitochondrial interior (matrix) |
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Download this section (compressed HTML)Q: What fraction of native arginine and agmatine turnover is carried by each paralog in particular tissues and stress conditions?
Q: How is mitochondrial versus plastid partitioning controlled, and is a stable cytosolic pool present?
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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