purN

UniProt ID: Q88MB0
Organism: Pseudomonas putida (strain ATCC 47054 / DSM 6125 / CFBP 8728 / NCIMB 11950 / KT2440)
Review Status: DRAFT
📝 Provide Detailed Feedback

Gene Description

PurN is the 10-formyltetrahydrofolate-dependent GAR transformylase that forms FGAR during de novo IMP synthesis. Pseudomonas putida also encodes the formate-dependent PurT alternative for this pathway position.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0003824 catalytic activity
IEA
GO_REF:0000117 		MODIFY
Summary: Correct but less informative than the enzyme-specific activity.
Reason: Replace the generic catalytic parent with phosphoribosylglycinamide formyltransferase activity.
GO:0004644 phosphoribosylglycinamide formyltransferase activity
IEA
GO_REF:0000120 		ACCEPT
Summary: Correct enzyme-specific molecular function.
Reason: The exact Phosphoribosylglycinamide formyltransferase product assignment supports this activity.
GO:0005737 cytoplasm
IEA
GO_REF:0000118 		KEEP AS NON CORE
Summary: Plausible broad electronic localization that is not core to the enzyme function.
Reason: Cytoplasm is consistent with a soluble bacterial metabolic enzyme, but it is broad, electronically inferred, and not supported by direct localization evidence.
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: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:0009152 purine ribonucleotide biosynthetic process
IEA
GO_REF:0000104 		MODIFY
Summary: Correct but broader than the specific pathway assignment.
Reason: Replace the broad purine-ribonucleotide process with de novo IMP biosynthesis.

Core Functions

Transfers a folate-derived formyl group to GAR during de novo IMP synthesis.

Molecular Function:
phosphoribosylglycinamide formyltransferase activity
Directly Involved In:
'de novo' IMP biosynthetic process
Supporting Evidence:
  • file:PSEPK/purN/purN-uniprot.txt
    RecName: Full=Phosphoribosylglycinamide formyltransferase
  • file:PSEPK/purN/purN-deep-research-openscientist.md
    The gene **purN** (ordered locus **PP_1664**; UniProt **Q88MB0**) of *Pseudomonas putida* KT2440 encodes a **folate-dependent glycinamide ribonucleotide (GAR) transformylase**
  • PMID:8501063
    We demonstrate here that Escherichia coli synthesizes two different glycinamide ribonucleotide (GAR) transformylases, both catalyzing the third step in the purine biosynthetic pathway.

References

Loading supporting content…

Download this section (compressed HTML)

Suggested Questions for Experts

Q: Under which carbon and folate conditions does PurN rather than PurT provide most GAR transformylase flux?

Suggested Experiments

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

Deep Research

OpenScientist

(purN-deep-research-openscientist.md)

Loading supporting content…

Download this section (compressed HTML)

📚 Additional Documentation

Notes

(purN-notes.md)

purN curation notes

  • UniProt identifies Q88MB0 as Phosphoribosylglycinamide formyltransferase [file:PSEPK/purN/purN-uniprot.txt "RecName: Full=Phosphoribosylglycinamide formyltransferase"].
  • E. coli genetics established PurN and PurT as alternative enzymes at this pathway
    position; either route can support purine synthesis PMID:8501063.
  • Replace generic catalytic activity and broad purine biosynthesis with the
    exact activity and GO:0006189, respectively. Retain both electronic
    cytoplasm and cytosol localizations as plausible but non-core.
  • Open question: Under which carbon and folate conditions does PurN rather than PurT provide most GAR transformylase flux?

📄 View Raw YAML

Loading supporting content…

Download this section (compressed HTML)