TrpC (PA0651) is the monofunctional indole-3-glycerol phosphate synthase (IGPS, EC 4.1.1.48) of Pseudomonas aeruginosa. It catalyses the ring-closing decarboxylation of 1-(2-carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate to indole-3-glycerol phosphate, CO2 and water, a step of L-tryptophan biosynthesis from chorismate. The purified enzyme is active over a broad pH range and has the highest turnover number reported for an IGPS (kcat about 11 per second). Deleting trpC reduces the fitness of PAO1 in synthetic cystic fibrosis sputum medium.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000162 L-tryptophan biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000523336, seeded by M. tuberculosis TrpC (IDA), E. coli TrpC (IMP) and the PseudoCAP row on P20577 itself (expected, not circular). Reason: IGPS catalyses a step of tryptophan biosynthesis; core process. Supporting Evidence: PMID:22555873 has the highest turnover number of any characterized IGPS (k (cat) = 11.1 ± 0.1 s(-1)) |
| GO:0000162 L-tryptophan biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: UniRule/UniPathway mapping. Reason: Consistent with the IBA and the curated pathway statement. Supporting Evidence: file:PSEAE/trpC/trpC-uniprot.txt Amino-acid biosynthesis; L-tryptophan biosynthesis; L-tryptophan from chorismate |
| GO:0000162 L-tryptophan biosynthetic process | IMP PMID:22555873 Characterization of the indole-3-glycerol phosphate synthase... | ACCEPT | Summary: PseudoCAP seed row. The abstract's mutant phenotype is reduced fitness in synthetic sputum rather than auxotrophy, but the same paper shows the purified enzyme catalyses the IGPS step, so the process term holds. Reason: Seed verdict SOUND for the term; the enzyme does the work of this step. Supporting Evidence: PMID:22555873 PaIGPS catalyzes the fifth reaction in the synthesis of tryptophan from chorismate |
| GO:0004425 indole-3-glycerol-phosphate synthase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000523336; E. coli, M. tuberculosis and Arabidopsis seeds plus P20577 itself. Reason: Core activity, directly measured for this protein. Supporting Evidence: PMID:22555873 has the highest turnover number of any characterized IGPS (k (cat) = 11.1 ± 0.1 s(-1)) |
| GO:0004425 indole-3-glycerol-phosphate synthase activity | IDA PMID:22555873 Characterization of the indole-3-glycerol phosphate synthase... | ACCEPT | Summary: PseudoCAP seed row; purified enzyme with measured kcat. Reason: Seed verdict SOUND; direct assay. Supporting Evidence: PMID:22555873 has the highest turnover number of any characterized IGPS (k (cat) = 11.1 ± 0.1 s(-1)) |
| GO:0004425 indole-3-glycerol-phosphate synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic mapping from IGPS family signatures and EC. Reason: Consistent with the direct assay. Supporting Evidence: file:PSEAE/trpC/trpC-uniprot.txt Belongs to the TrpC family. |
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Download this section (compressed HTML)Q: Is the trpC deletion a tryptophan auxotroph in minimal medium, and is its reduced fitness in synthetic CF sputum due to limited tryptophan there?
Experiment: Grow the trpC deletion in minimal medium with and without tryptophan, and in SCFM supplemented with tryptophan, to separate auxotrophy from other fitness effects.
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