gatB

UniProt ID: Q88PC0
Organism: Pseudomonas putida KT2440
Review Status: COMPLETE
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Gene Description

GatB is the ATP-dependent acceptor-side subunit of the soluble GatABC tRNA-dependent amidotransferase. With ammonia supplied by GatA and the structural support of GatC, it converts Asp-tRNA(Asn) to Asn-tRNA(Asn). The conserved complex also has Glu-tRNA(Gln)-to-Gln-tRNA(Gln) capacity when that substrate is available; these reactions modify the charged amino acid rather than form its ester bond to tRNA.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0003824 catalytic activity
IEA
GO_REF:0000002 		MODIFY
Summary: gatB has a defined role in the substrate-specific catalytic reaction.
Reason: Refine the broad activity to the supported asparaginyl-tRNA synthase (glutamine-hydrolyzing) activity, glutaminyl-tRNA synthase (glutamine-hydrolyzing) activity. The exact KT2440 curated family/rule assignment supports function by homology, not a purified-target experiment. Whole-complex activity includes the real contribution of this subunit; ordinary relationship metadata is not grounds for rejecting a supported contribution.
Supporting Evidence:
file:PSEPK/gatB/gatB-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; Evidence={ECO:0000255|HAMAP-Rule:MF_00121};
file:PSEPK/gatB/gatB-uniprot.txt
Belongs to the GatB/GatE family. GatB subfamily. {ECO:0000255|HAMAP-Rule:MF_00121}.
GO:0006412 translation
IEA
GO_REF:0000104 		MODIFY
Summary: gatB 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.
Supporting Evidence:
file:PSEPK/gatB/gatB-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; Evidence={ECO:0000255|HAMAP-Rule:MF_00121};
PMID:14729703
The pure heterotrimeric AdT of P. aeruginosa transamidates its homologous Asp-tRNA Asn into Asn-tRNA Asn (Fig. 6C ).
GO:0016874 ligase activity
IEA
GO_REF:0000120 		MODIFY
Summary: gatB has a defined role in the substrate-specific catalytic reaction.
Reason: Refine the broad activity to the supported asparaginyl-tRNA synthase (glutamine-hydrolyzing) activity, glutaminyl-tRNA synthase (glutamine-hydrolyzing) activity. The exact KT2440 curated family/rule assignment supports function by homology, not a purified-target experiment. Whole-complex activity includes the real contribution of this subunit; ordinary relationship metadata is not grounds for rejecting a supported contribution.
Supporting Evidence:
file:PSEPK/gatB/gatB-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; Evidence={ECO:0000255|HAMAP-Rule:MF_00121};
file:PSEPK/gatB/gatB-uniprot.txt
Belongs to the GatB/GatE family. GatB subfamily. {ECO:0000255|HAMAP-Rule:MF_00121}.
GO:0016884 carbon-nitrogen ligase activity, with glutamine as amido-N-donor
IEA
GO_REF:0000002 		MODIFY
Summary: gatB has a defined role in the substrate-specific catalytic reaction.
Reason: Refine the broad activity to the supported asparaginyl-tRNA synthase (glutamine-hydrolyzing) activity, glutaminyl-tRNA synthase (glutamine-hydrolyzing) activity. The exact KT2440 curated family/rule assignment supports function by homology, not a purified-target experiment. Whole-complex activity includes the real contribution of this subunit; ordinary relationship metadata is not grounds for rejecting a supported contribution.
Supporting Evidence:
file:PSEPK/gatB/gatB-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; Evidence={ECO:0000255|HAMAP-Rule:MF_00121};
file:PSEPK/gatB/gatB-uniprot.txt
Belongs to the GatB/GatE family. GatB subfamily. {ECO:0000255|HAMAP-Rule:MF_00121}.
GO:0030956 glutamyl-tRNA(Gln) amidotransferase complex
IEA
GO_REF:0000104 		ACCEPT
Summary: gatB 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/gatB/gatB-uniprot.txt
Heterotrimer of A, B and C subunits. {ECO:0000255|HAMAP- Rule:MF_00121}.
GO:0050566 asparaginyl-tRNA synthase (glutamine-hydrolyzing) activity
IEA
GO_REF:0000120 		ACCEPT
Summary: gatB contributes to Asn formation on tRNA within GatABC.
Reason: GatA supplies glutamine-derived ammonia, GatB carries the tRNA-bound acceptor activation/amidation machinery, and GatC supports the complex. The exact KT2440 conserved family/rule assignments and native PAO1 Asn-transamidation assay support the target capability by homology; no isolated-subunit complete reaction or direct KT2440 kinetics is asserted.
Supporting Evidence:
file:PSEPK/gatB/gatB-uniprot.txt
Heterotrimer of A, B and C subunits. {ECO:0000255|HAMAP- Rule:MF_00121}.
file:PSEPK/gatB/gatB-uniprot.txt
Belongs to the GatB/GatE family. GatB subfamily. {ECO:0000255|HAMAP-Rule:MF_00121}.
PMID:14729703
The pure heterotrimeric AdT of P. aeruginosa transamidates its homologous Asp-tRNA Asn into Asn-tRNA Asn (Fig. 6C ).
GO:0050567 glutaminyl-tRNA synthase (glutamine-hydrolyzing) activity
IEA
GO_REF:0000120 		KEEP AS NON CORE
Summary: gatB 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/gatB/gatB-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; Evidence={ECO:0000255|HAMAP-Rule:MF_00121};
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:0000120 		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.
Supporting Evidence:
file:PSEPK/gatB/gatB-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; Evidence={ECO:0000255|HAMAP-Rule:MF_00121};
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 .

Core Functions

Contributes ATP-dependent modification of tRNA-bound aspartate within GatABC.

Directly Involved In:
charged-tRNA amino acid modification
In Complex:
glutamyl-tRNA(Gln) amidotransferase complex
Supporting Evidence:
  • file:PSEPK/gatB/gatB-uniprot.txt
    Heterotrimer of A, B and C subunits. {ECO:0000255|HAMAP- Rule:MF_00121}.
  • file:PSEPK/gatB/gatB-uniprot.txt
    Belongs to the GatB/GatE family. GatB subfamily. {ECO:0000255|HAMAP-Rule:MF_00121}.
  • PMID:14729703
    The pure heterotrimeric AdT of P. aeruginosa transamidates its homologous Asp-tRNA Asn into Asn-tRNA Asn (Fig. 6C ).

References

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Suggested Questions for Experts

Q: Does native KT2440 GatABC convert supplied Glu-tRNA(Gln), and is that substrate produced in the cell?

Suggested Experiments

Experiment: Separate purified-complex substrate profiling from native aminoacyl-tRNA measurements; test supplied Glu-tRNA(Gln) and Asp-tRNA(Asn) without assuming an endogenous Gln-transamidation route.

📚 Additional Documentation

Notes

(gatB-notes.md)

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