HutU (PA5100) is the urocanase (urocanate hydratase, EC 4.2.1.49) of Pseudomonas aeruginosa PAO1, a soluble cytoplasmic enzyme with a tightly bound NAD+ cofactor. It catalyses step II of histidine degradation, hydrating trans-urocanate to 4-imidazolone-5-propanoate, between histidase (HutH) and imidazolonepropionase (HutI). The hut pathway lets P. aeruginosa use histidine as a carbon and nitrogen source; urocanate, the HutU substrate, is the physiological inducer of the pathway, so urocanase-deficient mutants express the other hut enzymes constitutively. HutU is the only urocanase-family protein in PAO1.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: HAMAP subcellular-location mapping; HutU is a soluble enzyme with no signal peptide or transmembrane segment. Reason: Urocanase acts on cytoplasmic urocanate made by histidase; the location is as precise as the evidence allows. Supporting Evidence: file:PSEAE/hutU/hutU-uniprot.txt Cytoplasm {ECO:0000255|HAMAP-Rule:MF_00577} |
| GO:0006548 L-histidine catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from the PTN002639709 IBD, seeded by human UROC1 (IMP, urocanic aciduria) and by this gene's own PseudoCAP row, which is expected. Reason: HutU catalyses step II of histidine degradation. The IBD stands on UROC1 as well as on the hutU seed. Supporting Evidence: PMID:4290562 Histidine ammonia lyase (histidase), urocanase, and the capacity to degrade formiminoglutamate, which are respectively involved in steps I, II, and IV in the catabolism of histidine PMID:16475788 The first three steps for the degradation of histidine include the action of HutH, HutU, and HutI to convert L-histidine to N-formimino-L-glutamate. |
| GO:0006548 L-histidine catabolic process | IEA GO_REF:0000104 | ACCEPT | Summary: UniRule (HAMAP MF_00577) transfer. Reason: Same claim as the IBA and IMP rows. Supporting Evidence: PMID:16475788 The first three steps for the degradation of histidine include the action of HutH, HutU, and HutI to convert L-histidine to N-formimino-L-glutamate. |
| GO:0006548 L-histidine catabolic process | IMP PMID:4290562 Formation and operation of the histidine-degrading pathway i... | ACCEPT | Summary: PseudoCAP row and a seed of PTN002639709. The paper describes a urocanase-deficient mutant and places urocanase at step II of histidine catabolism. Reason: Seed verdict SOUND. The enzyme performs a step of the pathway, and the mutant maps to PA5100, the only urocanase-family protein in PAO1 (pre-cloning paper; assignment by inference). Supporting Evidence: PMID:4290562 Histidine ammonia lyase (histidase), urocanase, and the capacity to degrade formiminoglutamate, which are respectively involved in steps I, II, and IV in the catabolism of histidine file:PSEAE/hutU/hutU-notes.md returns one protein, Q9HU83 hutU PA5100 |
| GO:0016153 urocanate hydratase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from the three-seed PTN002639709 IBD (human UROC1 IDA, B. subtilis HutU EXP, and this gene). Reason: Core activity. HutU carries the urocanase family signatures and the HAMAP-defined active site and NAD+-binding residues; the node term suits this conserved single-function family. Supporting Evidence: file:PSEAE/hutU/hutU-uniprot.txt Belongs to the urocanase family PMID:4290562 Urocanase-deficient bacteria formed enzymes I and IV constitutively; presumably they accumulate enough urocanate from the breakdown of endogenous histidine to induce formation of the pathway. |
| GO:0016153 urocanate hydratase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined electronic mapping (HAMAP, InterPro urocanase signatures, EC 4.2.1.49). Reason: Same claim as the IBA and IMP rows. Supporting Evidence: file:PSEAE/hutU/hutU-uniprot.txt Belongs to the urocanase family |
| GO:0016153 urocanate hydratase activity | IMP PMID:4290562 Formation and operation of the histidine-degrading pathway i... | ACCEPT | Summary: PseudoCAP row and a seed of PTN002639709. The paper assays urocanase in P. aeruginosa and describes a urocanase-deficient mutant. Reason: Seed verdict SOUND. Loss of urocanase activity in a mutant whose other hut enzymes are still induced fits a lesion in the structural gene, and PA5100 is the only urocanase-family protein in PAO1. The paper predates cloning, so the gene assignment is an inference, but a secure one. The IBD also stands on human UROC1 and B. subtilis HutU. Supporting Evidence: PMID:4290562 Urocanase-deficient bacteria formed enzymes I and IV constitutively; presumably they accumulate enough urocanate from the breakdown of endogenous histidine to induce formation of the pathway. file:PSEAE/hutU/hutU-notes.md returns one protein, Q9HU83 hutU PA5100 |
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