GatA is the glutamine-hydrolyzing subunit of the soluble GatABC tRNA-dependent amidotransferase. It supplies ammonia for conversion of the amino acid already attached to tRNA, supporting Asn-tRNA(Asn) formation from Asp-tRNA(Asn). The conserved complex can also support Gln-forming transamidation when Glu-tRNA(Gln) is supplied.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | MODIFY | Summary: Refine broad catalytic activity to the glutaminase chemistry supplied by GatA. Reason: GatA supplies the glutamine-hydrolysis step; Bacillus subunit assays distinguish this chemistry from ATP-dependent transamidation by the assembled GatCAB complex. Refine the generic catalytic term to glutaminase activity, supported by the target GatA-family assignment and comparative subunit biochemistry. Existing complete-complex activity rows and core-function contributions retain the supported role in transamidation; this refinement does not reject those contributions. Proposed replacements: glutaminase activity Supporting Evidence: file:PSEPK/gatA/gatA-uniprot.txt Belongs to the amidase family. GatA subfamily. PMID:9342321 The holoenzyme and the A subunit (coexpressed A+C) carry out the Gln → Glu conversion; ATP is not required for this reaction. |
| GO:0004359 glutaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: GatA hydrolyzes glutamine to supply ammonia for GatABC-dependent tRNA transamidation. Reason: The target curated HAMAP GatA-subfamily assignment supports conserved glutaminase chemistry. BACSU GatA coexpressed with GatC directly hydrolyzes glutamine without ATP in PMID:9342321. This is comparative biochemical support, not purified KT2440 activity or an assertion that isolated GatA performs the complete tRNA transamidation reaction. Supporting Evidence: file:PSEPK/gatA/gatA-uniprot.txt Belongs to the amidase family. GatA subfamily. PMID:9342321 The holoenzyme and the A subunit (coexpressed A+C) carry out the Gln → Glu conversion; ATP is not required for this reaction. |
| GO:0005737 cytoplasm | IEA GO_REF:0000117 | ACCEPT | Summary: Conserved GatA machinery and native Bacillus soluble-fraction evidence support an inferred cytoplasmic location. Reason: Cytoplasm is supported as a conserved-machinery inference: native B. subtilis GatCAB activity and immunoreactive subunits occur in S100 extracts (PMID:9342321), and the target curated HAMAP GatA-subfamily assignment supports the same intracellular tRNA-transamidation role. This is comparative support for the broad bacterial compartment, not a direct KT2440 localization assay or a claim of exclusive localization. Complex membership alone is not localization evidence. Supporting Evidence: PMID:9342321 The antibodies were able to neutralize the activity of the pure heterotrimeric Glu-AdT and also destroy all enzyme activity in crude B. subtilis S100 extracts (data not shown). PMID:9342321 All other lanes contain proteins of S100 cell extracts from wild-type B. subtilis (lane 3), E. coli BL21(DE3) containing the empty expression vector (lane 2), and E. coli cells containing pCAB (lane 4), pB (lane 7), or pC (lane 8). file:PSEPK/gatA/gatA-uniprot.txt Belongs to the amidase family. GatA subfamily. |
| GO:0006412 translation | IEA GO_REF:0000120 | MODIFY | Summary: gatA performs a defined chemical step supplying translation substrates. Reason: GatABC covalently amidates an amino acid already esterified to tRNA. The direct process is charged-tRNA amino acid modification, not formation of the amino-acid–tRNA ester bond. This is a lateral mechanistic correction rather than an assertion that GO:0019988 is a descendant of translation. Proposed replacements: charged-tRNA amino acid modification Supporting Evidence: file:PSEPK/gatA/gatA-uniprot.txt Reaction=L-glutamyl-tRNA(Gln) + L-glutamine + ATP + H2O = L-glutaminyl- tRNA(Gln) + L-glutamate + ADP + phosphate + H(+); Xref=Rhea:RHEA:17521, Rhea:RHEA-COMP:9681, Rhea:RHEA-COMP:9684, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:29985, ChEBI:CHEBI:30616, ChEBI:CHEBI:43474, ChEBI:CHEBI:58359, ChEBI:CHEBI:78520, ChEBI:CHEBI:78521, ChEBI:CHEBI:456216; EC=6.3.5.7; Evidence={ECO:0000255|HAMAP-Rule:MF_00120}; PMID:14729703 The pure heterotrimeric AdT of P. aeruginosa transamidates its homologous Asp-tRNA Asn into Asn-tRNA Asn (Fig. 6C ). |
| GO:0030956 glutamyl-tRNA(Gln) amidotransferase complex | IEA GO_REF:0000120 | ACCEPT | Summary: gatA is a structural member of the GatABC heterotrimer. Reason: The exact curated A/B/C heterotrimer assignment supports complex membership. Its historical Gln-oriented name does not exclude the native Asn-forming implementation, and no alternative oligomeric stoichiometry is inferred. Supporting Evidence: file:PSEPK/gatA/gatA-uniprot.txt Heterotrimer of A, B and C subunits. {ECO:0000255|HAMAP- Rule:MF_00120}. |
| GO:0050567 glutaminyl-tRNA synthase (glutamine-hydrolyzing) activity | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: gatA contributes to the conserved GatABC Gln-forming biochemical capacity. Reason: The curated heterotrimer reaction and direct PAO1 assay with supplied B. subtilis Glu-tRNA(Gln) support a real substrate capacity. PAO1 uses its Asn route natively, and KT2440 native Gln-transamidation flux is not established. Retain the secondary capacity without presenting it as a demonstrated physiological KT2440 route. Supporting Evidence: file:PSEPK/gatA/gatA-uniprot.txt Reaction=L-glutamyl-tRNA(Gln) + L-glutamine + ATP + H2O = L-glutaminyl- tRNA(Gln) + L-glutamate + ADP + phosphate + H(+); Xref=Rhea:RHEA:17521, Rhea:RHEA-COMP:9681, Rhea:RHEA-COMP:9684, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:29985, ChEBI:CHEBI:30616, ChEBI:CHEBI:43474, ChEBI:CHEBI:58359, ChEBI:CHEBI:78520, ChEBI:CHEBI:78521, ChEBI:CHEBI:456216; EC=6.3.5.7; Evidence={ECO:0000255|HAMAP-Rule:MF_00120}; PMID:14729703 The heterotrimeric AdT of P. aeruginosa has no Glu-tRNA Gln substrate in its host, but it can transamidate heterologous Glu-tRNA Gln . |
| GO:0070681 glutaminyl-tRNAGln biosynthesis via transamidation | IEA GO_REF:0000104 | MODIFY | Summary: GatABC modifies a charged amino acid; the former pathway-variant BP is obsolete. Reason: Current QuickGO explicitly retires GO:0070681 and distinguishes GatCAB modification of already-charged tRNA from charging itself. KT2440 conserved GatABC and non-discriminating AspS support the Asn-forming modification route by inference. PAO1 shows an additional in vitro Gln-forming capacity with supplied heterologous substrate, not a native KT2440 Gln-transamidation pathway. Replace the obsolete overly specific pathway claim with the supported modification process. Proposed replacements: charged-tRNA amino acid modification Supporting Evidence: file:PSEPK/gatA/gatA-uniprot.txt Reaction=L-glutamyl-tRNA(Gln) + L-glutamine + ATP + H2O = L-glutaminyl- tRNA(Gln) + L-glutamate + ADP + phosphate + H(+); Xref=Rhea:RHEA:17521, Rhea:RHEA-COMP:9681, Rhea:RHEA-COMP:9684, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:29985, ChEBI:CHEBI:30616, ChEBI:CHEBI:43474, ChEBI:CHEBI:58359, ChEBI:CHEBI:78520, ChEBI:CHEBI:78521, ChEBI:CHEBI:456216; EC=6.3.5.7; Evidence={ECO:0000255|HAMAP-Rule:MF_00120}; PMID:14729703 The pure heterotrimeric AdT of P. aeruginosa transamidates its homologous Asp-tRNA Asn into Asn-tRNA Asn (Fig. 6C ). PMID:14729703 The heterotrimeric AdT of P. aeruginosa has no Glu-tRNA Gln substrate in its host, but it can transamidate heterologous Glu-tRNA Gln . |
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Experiment: Reconstitute KT2440 GatABC with each charged-tRNA substrate, measuring ammonia/glutamate production alongside the tRNA-bound amino-acid product and controlled GatA catalytic substitutions.
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