PA1566 (PauA3) is one of seven glutamine synthetase-like gamma-glutamylpolyamine synthetases (PauA1-PauA7) of Pseudomonas aeruginosa PAO1, homologous to Escherichia coli PuuA, the first enzyme of the gamma-glutamylation pathway that converts polyamines to GABA. PA1566 is encoded with pauB2 in the spermidine- and diaminopropane-inducible pauA3B2 operon, and a pauA3 mutant grows poorly on 1,3-diaminopropane, so it is thought to gamma-glutamylate diaminopropane (derived from the aminopropyl moiety of spermidine) for catabolism. Its enzymatic activity and substrate have not been measured with purified protein.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro2GO from the GS/guanido kinase catalytic domain. Reason: Entailed by GO:0016880 acid-ammonia (or amide) ligase activity, the core function MF. |
| GO:0004356 glutamine synthetase activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO from the GS catalytic and N-terminal domain signatures, which do not separate glutamine synthetases from their gamma-glutamylpolyamine synthetase paralogs. Reason: The domain and reaction class (ATP-dependent ligation of L-glutamate to an amine) are right, the substrate is not. PA1566 belongs to the PuuA (gamma-glutamylputrescine synthetase) family and the genetics place it in diaminopropane catabolism; P. aeruginosa has a dedicated glutamine synthetase, GlnA. Generalize to the parent reaction class until the substrate is measured. Proposed replacements: acid-ammonia (or amide) ligase activity Supporting Evidence: file:PSEAE/PA1566/PA1566-uniprot.txt PANTHER; PTHR43785; GAMMA-GLUTAMYLPUTRESCINE SYNTHETASE; 1. PMID:21622750 Mutation analysis led to the conclusion that pauA3B2 participate in catabolism of DAP |
| GO:0006598 polyamine catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN001839150 (10 leaf IBAs, 4 taxa), seeded by E. coli PuuA (IMP putrescine catabolism, IDA glutamate-putrescine ligase), PA1566 itself (expected, not circular), SpuB/PauA2 and SpuI/PauA1. The IBD stands without this seed. Reason: Correct and as specific as GO allows for diaminopropane catabolism (no dedicated GO term). Consistent with the IMP seed row. Supporting Evidence: PMID:21622750 Mutation analysis led to the conclusion that pauA3B2 participate in catabolism of DAP, which is related to the aminopropyl moiety of Spd |
| GO:0006598 polyamine catabolic process | IMP PMID:21622750 Functional characterization of seven Ξ³-Glutamylpolyamine syn... | ACCEPT | Summary: PseudoCAP seed row for PTN001839150. The pauA3 mutant is retarded for growth on 1,3-diaminopropane (a polyamine). Seed verdict SOUND. Reason: Growth on a polyamine as sole source is the pathway readout, and PA1566 is the predicted first (gamma-glutamylation) enzyme of that pathway, so it performs a step of the process. GO has no diaminopropane catabolism term, so the general term is the right one. Supporting Evidence: PMID:21622750 Mutation analysis led to the conclusion that pauA3B2 participate in catabolism of DAP, which is related to the aminopropyl moiety of Spd |
| GO:0016874 ligase activity | IEA GO_REF:0000117 | TOO GENERAL | Summary: ARBA ligase activity. Reason: Entailed by GO:0016880 acid-ammonia (or amide) ligase activity, the core function MF. |
| GO:1901704 L-glutamine biosynthetic process | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: IBA from the deep GS-family node PTN000464978, seeded by Bacillus subtilis GlnA (P12425). PA1566 sits in the PuuA-like gamma-glutamylpolyamine synthetase clade (PTN001839150). Reason: Over-propagation of the ancestral glutamine synthetase role to a substrate-diverged paralog. The genetics put PA1566 in diaminopropane catabolism, the enzyme family is gamma-glutamylputrescine synthetase, and GlnA supplies glutamine in P. aeruginosa. Not REMOVE because no assay has excluded residual glutamine synthesis. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE Sources checked: PANTHER:PTN000464978 Β· PTN000464978 SUPPORTS SOURCE BUT NOT TARGET GS-family node; glutamine biosynthesis is right for GlnA but the PuuA/PauA subclade uses polyamines in place of ammonia. UniProtKB:P12425 Β· B. subtilis GlnA SUPPORTS SOURCE BUT NOT TARGET Bona fide glutamine synthetase. Supporting Evidence: file:PSEAE/PA1566/PA1566-uniprot.txt PANTHER; PTHR43785; GAMMA-GLUTAMYLPUTRESCINE SYNTHETASE; 1. |
| GO:1901704 L-glutamine biosynthetic process | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: InterPro2GO from the GS N-terminal domain superfamily. Reason: Same claim and reasoning as the IBA row. |
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Download this section (compressed HTML)Q: Is 1,3-diaminopropane the preferred substrate of PauA3, and does it also gamma-glutamylate the aminopropyl part of spermidine directly?
Experiment: Purify PA1566 and measure ATP-dependent gamma-glutamylation of 1,3-diaminopropane, putrescine, cadaverine, spermidine and ammonia (glutamine synthetase activity) to define its substrate range.
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