AJ80_06654 encodes a predicted copper-containing nitrite reductase in the fungus Polytolypa hystricis UAMH7299. The protein belongs to the multicopper oxidase/cupredoxin nitrite reductase family and is predicted to catalyze NO-forming reduction of nitrite to nitric oxide, using a type 1 copper electron-transfer site and a type 2 copper catalytic site. Its physiological role and subcellular compartment in this fungus have not been experimentally characterized.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005507 copper ion binding | IEA GO_REF:0000002 | ACCEPT | Summary: ACCEPT. Copper binding is consistent with the predicted copper-containing nitrite reductase family. Reason: The UniProt record includes cupredoxin/multicopper oxidase family signatures and conserved type 1 copper-site features. These support copper binding even though no species-specific biochemical study was found. Falcon supports T1Cu/T2Cu architecture as the conserved CuNIR mechanism. Supporting Evidence: file:POLH7/AJ80_06654/AJ80_06654-uniprot.txt Belongs to the multicopper oxidase family. file:POLH7/AJ80_06654/AJ80_06654-uniprot.txt InterPro; IPR001287; NO2-reductase_Cu. file:POLH7/AJ80_06654/AJ80_06654-deep-research-falcon.md catalytic site where nitrite binds and is reduced to NO. |
| GO:0016491 oxidoreductase activity | IEA GO_REF:0000118 | KEEP AS NON CORE | Summary: KEEP_AS_NON_CORE. Correct but less informative than NO-forming nitrite reductase activity. Reason: The oxidoreductase parent is consistent with nitrite reductase chemistry, but GO:0050421 is the informative function supported by the EC and family assignments. Supporting Evidence: file:POLH7/AJ80_06654/AJ80_06654-uniprot.txt RecName: Full=Copper-containing nitrite reductase |
| GO:0042597 periplasmic space | IEA GO_REF:0000044 | UNDECIDED | Summary: UNDECIDED. This bacterial-style localization should not be accepted for a fungal protein without stronger subcellular evidence. Reason: The sequence has a UniProt periplasm prediction but the gene is fungal, and the local evidence does not establish whether this protein is secreted, cell-wall/periplasm-associated, or membrane-associated. The predicted transmembrane segment further argues against accepting a simple bacterial-style periplasm transfer without organism-specific evidence. Falcon confirms that bacterial CuNIRs are commonly periplasmic but that this compartment does not translate cleanly to a filamentous fungus. Supporting Evidence: file:POLH7/AJ80_06654/AJ80_06654-uniprot.txt SUBCELLULAR LOCATION: Periplasm file:POLH7/AJ80_06654/AJ80_06654-uniprot.txt TRANSMEM 82..98 file:POLH7/AJ80_06654/AJ80_06654-deep-research-falcon.md For AJ80_06654 in a filamentous fungus, extracellular/periplasm-equivalent or secretory localization is plausible but unverified. |
| GO:0050421 nitrite reductase (NO-forming) activity | IEA GO_REF:0000120 | ACCEPT | Summary: ACCEPT. The predicted copper-containing nitrite reductase assignment supports this molecular function. Reason: The best-supported assertion is molecular activity, not organism-level pathway membership. UniProt assigns EC 1.7.2.1 and the sequence carries NO2-reductase_Cu/cupredoxin family signatures, making this a reasonable conserved-function inference. PTHR11709 is a broad multicopper oxidase family, so the specific nitrite reductase call should rely on the EC and NO2-reductase_Cu evidence rather than PANTHER root membership alone. Falcon adds current CuNIR mechanism: T1Cu transfers electrons to the T2Cu nitrite-binding catalytic site for NO formation. Supporting Evidence: file:POLH7/AJ80_06654/AJ80_06654-uniprot.txt RecName: Full=Copper-containing nitrite reductase file:POLH7/AJ80_06654/AJ80_06654-uniprot.txt PANTHER; PTHR11709; MULTI-COPPER OXIDASE file:interpro/panther/PTHR11709/PTHR11709-deep-research-falcon.md Across fungi, recent phylogenomic synthesis supports distinct MCO clades with different predicted functions file:POLH7/AJ80_06654/AJ80_06654-deep-research-falcon.md Nitrite binding at the catalytic copper site is supported by recent structural studies |
| GO:0019333 denitrification pathway | IEA GO_REF:0000041 | UNDECIDED | Summary: UNDECIDED. A NO-forming nitrite reductase can participate in denitrification, but this is a singleton fungal UniPathway row and no organism-specific experimental support was available in the local review. Reason: Conserved NO-forming nitrite reductase activity supports possible denitrification chemistry, but the review lacks species-specific evidence that P. hystricis runs a complete denitrification pathway or that this fungal protein functions in that pathway in vivo. Keep the molecular function, but leave the pathway assertion unresolved. Falcon found broad fungal nirK ecological evidence, but not direct P. hystricis pathway evidence. Supporting Evidence: file:POLH7/AJ80_06654/AJ80_06654-uniprot.txt PATHWAY: Nitrogen metabolism; nitrate reduction (denitrification); file:POLH7/AJ80_06654/AJ80_06654-uniprot.txt RecName: Full=Copper-containing nitrite reductase file:interpro/panther/PTHR11709/PTHR11709-deep-research-falcon.md Across fungi, recent phylogenomic synthesis supports distinct MCO clades with different predicted functions file:POLH7/AJ80_06654/AJ80_06654-deep-research-falcon.md the scanned text did not provide usable evidence about this gene or denitrification capability |
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