KynB (PA2081) is the bacterial kynurenine formamidase (arylformamidase, EC 3.5.1.9), a zinc-dependent amidase of the cyclase superfamily. It hydrolyses N-formyl-L-kynurenine to L-kynurenine and formate, the second step of the aerobic kynurenine pathway that converts L-tryptophan to anthranilate together with tryptophan 2,3-dioxygenase (KynA) and kynureninase (KynU). The recombinant P. aeruginosa enzyme is active, and crystal structures of the bacterial enzymes show a homodimer with a binuclear Zn2+ catalytic centre in a confined active site.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004061 arylformamidase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN001258690 (163 leaves, 62 taxa). Seeds are KynB itself (expected self-seed) and B. cereus KynB (Q81CK1, IDA PMID:14592712). Stands without this seed. Reason: Core activity; directly assayed for the P. aeruginosa enzyme. Supporting Evidence: PMID:14592712 This functional prediction was experimentally verified by cloning, expression and enzymatic characterization of recombinant kynurenine formamidase orthologs from Bacillus cereus, Pseudomonas aeruginosa and Ralstonia metallidurans. PMID:24942958 In the present study, we characterize the catalytic properties and present the crystal structures of three bacterial kynurenine formamidases. |
| GO:0004061 arylformamidase activity | IDA PMID:14592712 Aerobic tryptophan degradation pathway in bacteria: novel ky... | ACCEPT | Summary: PseudoCAP seed row for PTN001258690. Seed verdict SOUND: the abstract states the P. aeruginosa ortholog was expressed and enzymatically characterised. Reason: Direct assay of the recombinant enzyme. Supporting Evidence: PMID:14592712 This functional prediction was experimentally verified by cloning, expression and enzymatic characterization of recombinant kynurenine formamidase orthologs from Bacillus cereus, Pseudomonas aeruginosa and Ralstonia metallidurans. |
| GO:0004061 arylformamidase activity | IDA PMID:24942958 Structures of bacterial kynurenine formamidase reveal a crow... | ACCEPT | Summary: Purified PaKynB assayed and crystallised. Reason: Direct biochemical evidence. Supporting Evidence: PMID:24942958 In the present study, we characterize the catalytic properties and present the crystal structures of three bacterial kynurenine formamidases. |
| GO:0004061 arylformamidase activity | IEA GO_REF:0000120 | ACCEPT | Summary: EC/Rhea/UniRule mapping to the same activity. Reason: Consistent with the experimental rows. Supporting Evidence: PMID:14592712 This functional prediction was experimentally verified by cloning, expression and enzymatic characterization of recombinant kynurenine formamidase orthologs from Bacillus cereus, Pseudomonas aeruginosa and Ralstonia metallidurans. |
| GO:0004328 formamidase activity | IEA GO_REF:0000002 | REMOVE | Summary: InterPro IPR017484 (kynurenine formamidase, bacterial) mapped to formamidase activity, which is hydrolysis of formamide to formate and ammonia (EC 3.5.1.49), a different reaction. Reason: Wrong InterPro2GO mapping: KynB hydrolyses the N-formyl group of N-formylkynurenine (arylformamidase, EC 3.5.1.9), and GO:0004061 is not a child of GO:0004328. No evidence of formamide hydrolysis. Supporting Evidence: PMID:14592712 we have identified a previously unknown gene encoding for kynurenine formamidase (EC 3.5.1.19) involved with the second step of the anthranilate pathway |
| GO:0006569 L-tryptophan catabolic process | IEA GO_REF:0000120 | ACCEPT | Summary: UniRule/InterPro mapping to tryptophan catabolism. Reason: KynB catalyses step 2 of the kynurenine pathway. Supporting Evidence: PMID:14592712 we have identified a previously unknown gene encoding for kynurenine formamidase (EC 3.5.1.19) involved with the second step of the anthranilate pathway |
| GO:0006569 L-tryptophan catabolic process | IGC PMID:14592712 Aerobic tryptophan degradation pathway in bacteria: novel ky... | ACCEPT | Summary: UniProt IGC from the gene-cluster analysis and reconstitution of the kynBAU pathway. Reason: Direct participation (catalytic step) in L-tryptophan catabolism. Supporting Evidence: PMID:14592712 we have identified a previously unknown gene encoding for kynurenine formamidase (EC 3.5.1.19) involved with the second step of the anthranilate pathway |
| GO:0008270 zinc ion binding | IDA PMID:24942958 Structures of bacterial kynurenine formamidase reveal a crow... | ACCEPT | Summary: Binuclear Zn2+ centre seen in the crystal structures. Reason: Catalytic zinc cofactor shown structurally. Supporting Evidence: PMID:24942958 The structures reveal a new amidase protein fold, a highly organized and distinctive binuclear Zn2+ catalytic centre |
| GO:0008270 zinc ion binding | IEA GO_REF:0000104 | ACCEPT | Summary: UniRule cofactor mapping. Reason: Consistent with the structural evidence. Supporting Evidence: PMID:24942958 The structures reveal a new amidase protein fold, a highly organized and distinctive binuclear Zn2+ catalytic centre |
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Experiment: Measure kynurenine-pathway flux and anthranilate supply in a kynB deletion of PAO1 grown on tryptophan.
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