TrpA (PA0035) is the alpha subunit of tryptophan synthase (EC 4.2.1.20) of Pseudomonas aeruginosa. It catalyses the aldol cleavage of indole-3-glycerol phosphate to indole and glyceraldehyde 3-phosphate; the indole is passed to the beta subunit TrpB, which condenses it with L-serine to give L-tryptophan, the last step of tryptophan biosynthesis. The enzyme is a cytoplasmic alpha2beta2 tetramer. trpA lies downstream of trpB in a trpBA operon in which the two cistrons overlap by 4 bp, and a plasmid-borne P. aeruginosa alpha subunit forms a functional enzyme with the E. coli beta2 subunit in vivo.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000162 L-tryptophan biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000034360 (tryptophan synthase alpha clade). Seeds are E. coli TrpA P0A877, Arabidopsis TSA1 AT3G54640 and TrpA itself; the self-seed reflects the gene's own experimental row and is expected. Reason: Core process; the IBD rests on well-characterized E. coli and plant orthologs. Supporting Evidence: file:PSEAE/trpA/trpA-uniprot.txt The alpha subunit is responsible for the aldol cleavage of indoleglycerol phosphate to indole and glyceraldehyde 3-phosphate. PMID:3127651 We also report the construction of a recombinant plasmid that overproduces a slightly modified alpha subunit from P. aeruginosa that can form a functionally effective multimer with normal E. coli beta 2 subunit in vivo |
| GO:0000162 L-tryptophan biosynthetic process | IDA PMID:3127651 Nucleotide sequence of the genes for tryptophan synthase in ... | ACCEPT | Summary: PseudoCAP IDA and one of three seeds of the PTN000034360 IBD. Hadero and Crawford sequenced trpBA and showed that an overproduced P. aeruginosa alpha subunit forms a functionally effective multimer with E. coli beta2 in vivo. Reason: Seed is SOUND. The in vivo complementation shows that the P. aeruginosa alpha subunit does the alpha-subunit step of tryptophan synthesis; the evidence is closer to a complementation (IGI-like) assay than to a direct assay, but the term is right. Supporting Evidence: PMID:3127651 We also report the construction of a recombinant plasmid that overproduces a slightly modified alpha subunit from P. aeruginosa that can form a functionally effective multimer with normal E. coli beta 2 subunit in vivo |
| GO:0000162 L-tryptophan biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: UniRule/UniPathway mapping to the same process. Reason: Consistent with HAMAP family membership and the complementation data. Supporting Evidence: file:PSEAE/trpA/trpA-uniprot.txt The alpha subunit is responsible for the aldol cleavage of indoleglycerol phosphate to indole and glyceraldehyde 3-phosphate. file:PSEAE/trpA/trpA-uniprot.txt MF_00131; Trp_synth_alpha |
| GO:0000162 L-tryptophan biosynthetic process | NAS PMID:3127651 Nucleotide sequence of the genes for tryptophan synthase in ... | ACCEPT | Summary: PseudoCAP NAS from the same sequencing paper; same claim as the IDA row. Reason: Same true claim as the IDA row. Supporting Evidence: PMID:3127651 We also report the construction of a recombinant plasmid that overproduces a slightly modified alpha subunit from P. aeruginosa that can form a functionally effective multimer with normal E. coli beta 2 subunit in vivo |
| GO:0004834 tryptophan synthase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000034360, seeded for this term by Arabidopsis TSA1 (AT3G54640) and AT4G02610. GO:0004834 names the overall alpha2beta2 reaction, to which the alpha subunit contributes the indole-3-glycerol-phosphate cleavage step. Reason: Standard term for tryptophan synthase alpha chains; HAMAP and the complementation data agree. Supporting Evidence: file:PSEAE/trpA/trpA-uniprot.txt The alpha subunit is responsible for the aldol cleavage of indoleglycerol phosphate to indole and glyceraldehyde 3-phosphate. file:PSEAE/trpA/trpA-uniprot.txt MF_00131; Trp_synth_alpha |
| GO:0004834 tryptophan synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: InterPro/EC/RHEA mapping to tryptophan synthase activity. Reason: Same claim as the IBA row; family membership is unambiguous. Supporting Evidence: file:PSEAE/trpA/trpA-uniprot.txt MF_00131; Trp_synth_alpha |
| GO:0005829 cytosol | IBA GO_REF:0000033 | ACCEPT | Summary: IBA cytosol from PTN000034360, seeded by E. coli TrpA. Reason: Soluble biosynthetic enzyme without signal peptide or transmembrane segment; cytosolic location is expected. Supporting Evidence: file:PSEAE/trpA/trpA-uniprot.txt The alpha subunit is responsible for the aldol cleavage of indoleglycerol phosphate to indole and glyceraldehyde 3-phosphate. |
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Download this section (compressed HTML)Q: Has the P. aeruginosa alpha2beta2 complex been purified and its alpha-reaction kinetics compared with the E. coli enzyme, given the reported slight modification of the overproduced subunit?
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