purC

UniProt ID: Q88NG9
Organism: Pseudomonas putida KT2440
Review Status: DRAFT
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Gene Description

PurC is SAICAR synthetase, the ATP-dependent enzyme that condenses CAIR with aspartate to form SAICAR during de novo IMP synthesis.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0004639 phosphoribosylaminoimidazolesuccinocarboxamide synthase activity
IEA
GO_REF:0000120 		ACCEPT
Summary: Correct enzyme-specific molecular function.
Reason: Membership of the SAICAR synthetase family (HAMAP MF_00137, NCBIfam TIGR00081 purC) supports this activity; the HAMAP-rule SIMILARITY and reaction statements are family-rule inferences, and the KT2440 protein has not been assayed.
Supporting Evidence:
file:PSEPK/purC/purC-uniprot.txt
Belongs to the SAICAR synthetase family.
file:PSEPK/purC/purC-uniprot.txt
DR NCBIfam; TIGR00081; purC; 1.
GO:0005829 cytosol
IEA
GO_REF:0000118 		KEEP AS NON CORE
Summary: Plausible electronic localization that is not core to the enzyme function.
Reason: Cytosol is consistent with a soluble bacterial metabolic enzyme, but no direct localization evidence was found.
GO:0006164 purine nucleotide biosynthetic process
IEA
GO_REF:0000002 		MODIFY
Summary: Correct but broader than the specific pathway assignment.
Reason: Replace the broad purine-nucleotide process with de novo IMP biosynthesis.
GO:0006189 'de novo' IMP biosynthetic process
IEA
GO_REF:0000120 		ACCEPT
Summary: Correct pathway assignment.
Reason: This enzyme catalyzes a required reaction between PRPP and IMP.
GO:0009236 cobalamin biosynthetic process
IEA
GO_REF:0000002 		REMOVE
Summary: Unsupported pathway transfer from a broad enzyme-family mapping.
Reason: Canonical PurC catalyzes SAICAR formation in purine synthesis; no cobalamin role is supported.
Supporting Evidence:
file:PSEPK/purC/purC-uniprot.txt
RecName: Full=Phosphoribosylaminoimidazole-succinocarboxamide synthase

Core Functions

Forms SAICAR from CAIR and aspartate during de novo IMP synthesis.

Molecular Function:
phosphoribosylaminoimidazolesuccinocarboxamide synthase activity
Directly Involved In:
'de novo' IMP biosynthetic process
Supporting Evidence:
  • file:PSEPK/purC/purC-uniprot.txt
    Belongs to the SAICAR synthetase family.
  • file:PSEPK/purC/purC-uniprot.txt
    DR HAMAP; MF_00137; SAICAR_synth; 1.
  • file:PSEPK/purC/purC-uniprot.txt
    PATHWAY: Purine metabolism; IMP biosynthesis via de novo pathway

References

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Suggested Questions for Experts

Q: Should the cobalamin-process InterPro mapping be narrowed so it is not transferred to canonical PurC proteins?

Suggested Experiments

Experiment: Test a clean purC deletion for purine auxotrophy and rescue by the appropriate downstream purine intermediate or by gene complementation.

Deep Research

OpenScientist

(purC-deep-research-openscientist.md)

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📚 Additional Documentation

Notes

(purC-notes.md)

purC curation notes

  • UniProt identifies Q88NG9 as Phosphoribosylaminoimidazole-succinocarboxamide synthase [file:PSEPK/purC/purC-uniprot.txt "RecName: Full=Phosphoribosylaminoimidazole-succinocarboxamide synthase"].
  • Remove the cobalamin-process annotation because it conflicts with the exact PurC
    assignment and has no target-specific support. Replace the broad purine nucleotide
    process with GO:0006189.
  • Open question: Should the cobalamin-process InterPro mapping be narrowed so it is not transferred to canonical PurC proteins?

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