PP_0431

UniProt ID: Q88QQ7
Organism: Pseudomonas putida (strain ATCC 47054 / DSM 6125 / CFBP 8728 / NCIMB 11950 / KT2440)
Review Status: COMPLETE
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Gene Description

PP_0431 is a HemJ-family, multi-pass membrane protoporphyrinogen IX oxidase. It oxidizes protoporphyrinogen IX to protoporphyrin IX through a membrane-electron-acceptor reaction and binds one heme-b cofactor per subunit. The product is the macrocycle used by HemH in the terminal ferrochelation step of heme-b biosynthesis.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005886 plasma membrane
IEA
GO_REF:0000120 		ACCEPT
Summary: A cell-membrane location is characteristic of HemJ-family oxidases.
Reason: UniProt predicts a multi-pass cell-membrane protein; plasma membrane is the corresponding bacterial cellular-component term.
Supporting Evidence:
file:PSEPK/PP_0431/PP_0431-uniprot.txt
SUBCELLULAR LOCATION: Cell membrane
GO:0046872 metal ion binding
IEA
GO_REF:0000104 		MODIFY
Summary: The broad metal-binding call can be replaced by the identified heme-b cofactor interaction.
Reason: UniProt predicts one heme-b group per subunit. GO:0020037 captures that defined cofactor binding more precisely than generic metal ion binding.
Proposed replacements: heme binding
Supporting Evidence:
file:PSEPK/PP_0431/PP_0431-uniprot.txt
Binds 1 heme b (iron(II)-protoporphyrin IX) group per subunit.
GO:0070818 protoporphyrinogen oxidase activity
IEA
GO_REF:0000120 		ACCEPT
Summary: This is the specific HemJ-family catalytic activity.
Reason: UniProt assigns acceptor-dependent oxidation of protoporphyrinogen IX to protoporphyrin IX (RHEA:62000), without asserting molecular oxygen as the direct acceptor.
Supporting Evidence:
file:PSEPK/PP_0431/PP_0431-uniprot.txt
Catalyzes the oxidation of protoporphyrinogen IX to
GO:0006785 heme B biosynthetic process
IEA
file:PSEPK/PP_0431/PP_0431-uniprot.txt 		NEW
Summary: PP_0431 supplies protoporphyrin IX directly to ferrochelatase in heme-b synthesis.
Reason: The exact catalytic reaction and UniProt pathway assignment strongly place this HemJ enzyme in the route that produces heme B; its protoporphyrin IX product is the direct substrate of ferrochelatase.
Supporting Evidence:
file:PSEPK/PP_0431/PP_0431-uniprot.txt
biosynthesis; protoporphyrin-IX from protoporphyrinogen-IX: step 1/1.

Core Functions

Oxidizes protoporphyrinogen IX to protoporphyrin IX as a heme-b-binding, HemJ-family membrane enzyme immediately upstream of ferrochelatase.

Molecular Function:
protoporphyrinogen oxidase activity
Directly Involved In:
heme B biosynthetic process
Cellular Locations:
plasma membrane
Supporting Evidence:
  • file:PSEPK/PP_0431/PP_0431-uniprot.txt
    Catalyzes the oxidation of protoporphyrinogen IX to
  • file:PSEPK/PP_0431/PP_0431-uniprot.txt
    Binds 1 heme b (iron(II)-protoporphyrin IX) group per subunit.

References

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Suggested Questions for Experts

Q: Which native membrane electron acceptor couples to PP_0431 in KT2440?

Suggested Experiments

Experiment: Reconstitute PP_0431 in membranes with candidate quinones and test protoporphyrinogen oxidation, then measure heme-b synthesis after gene depletion and complementation.

Hypothesis: PP_0431 is the physiologically dominant protoporphyrinogen oxidase in KT2440.

Deep Research

OpenScientist

(PP_0431-deep-research-openscientist.md)

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📚 Additional Documentation

Notes

(PP_0431-notes.md)

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