moaE

UniProt ID: Q88NB8
Organism: Pseudomonas putida KT2440
Review Status: COMPLETE
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Gene Description

moaE (PP_1294) encodes the catalytic subunit of molybdopterin synthase. By orthology with Escherichia coli MoaE, two MoaE subunits form the central dimer of a MoaD2-MoaE2 heterotetramer and use the thiocarboxylated C termini of the sulfur-loaded MoaD carrier subunits to incorporate two sulfurs into cyclic pyranopterin monophosphate, forming the dithiolene of molybdopterin during molybdenum cofactor biosynthesis.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0006777 Mo-molybdopterin cofactor biosynthetic process
IEA
GO_REF:0000002 		ACCEPT
Summary: MoaE catalyzes the molybdopterin-forming step of Mo-cofactor biosynthesis.
Reason: Q88NB8 matches the InterPro and Pfam MoaE models that define the catalytic subunit of molybdopterin synthase. The E. coli ortholog converts precursor Z to molybdopterin, so the protein does work in the process. Same action as genes/ECOLI/moaE.
Supporting Evidence:
file:PSEPK/moaE/moaE-uniprot.txt
DR InterPro; IPR003448; Mopterin_biosynth_MoaE.
file:ECOLI/moaE/moaE-uniprot.txt
FUNCTION: Converts molybdopterin precursor Z to molybdopterin.
GO:0030366 molybdopterin synthase activity
IEA
GO_REF:0000120 		ACCEPT
Summary: Molybdopterin synthase activity is the exact core molecular function of MoaE.
Reason: The Rhea/EC 2.8.1.12 assignment on Q88NB8 is ARBA-derived and is not used as evidence. Support is family membership (Pfam PF02391 MoaE, CDD cd00756) plus the experimentally characterised E. coli ortholog P30749, whose reaction is recorded with PubMed-tied evidence. Same action as genes/ECOLI/moaE.
Supporting Evidence:
file:PSEPK/moaE/moaE-uniprot.txt
DR Pfam; PF02391; MoaE; 1.
file:ECOLI/moaE/moaE-uniprot.txt
Reaction=2 [molybdopterin-synthase sulfur-carrier protein]-C-terminal- Gly-aminoethanethioate + cyclic pyranopterin phosphate + H2O = molybdopterin + 2 [molybdopterin-synthase sulfur-carrier protein]-C- terminal Gly-Gly + 2 H(+)
file:PSEPK/moaE/moaE-deep-research-openscientist.md
The requirement for the thiocarboxylate form is strict: **only the thiocarboxylated MPT synthase complex is able to convert precursor Z to MPT in vitro** [PMID: 11459846](https://pubmed.ncbi.nlm.nih.gov/11459846/).
GO:0032324 molybdopterin cofactor biosynthetic process
IEA
GO_REF:0000117 		MODIFY
Summary: ARBA assignment of the broader molybdopterin cofactor biosynthesis parent term.
Reason: Correct but general (the earlier draft marked it over-annotated, but the term is true). GO:0032324 covers both Mo- and W-molybdopterin cofactors; its is_a child GO:0006777, which this gene already carries and which is accepted above, is the specific supported term. Same action as genes/ECOLI/moaE.
Supporting Evidence:
file:PSEPK/moaE/moaE-uniprot.txt
DR InterPro; IPR003448; Mopterin_biosynth_MoaE.
GO:1990140 molybdopterin synthase complex
ISS
file:PSEPK/moaE/moaE-uniprot.txt 		NEW
Summary: Q88NB8 is the catalytic subunit of the MoaD2-MoaE2 molybdopterin synthase complex.
Reason: The UniProt SUBUNIT line of Q88NB8 (2 MoaD + 2 MoaE heterotetramer) is an ARBA prediction and is not cited as evidence. Support is family membership: Q88NB8 matches the Pfam MoaE, CDD MoaE and InterPro Mopterin_biosynth_MoaE models, which define the large (catalytic) subunit of molybdopterin synthase; in the characterised E. coli member (P30749, the ISS source) that subunit forms the MoaD2-MoaE2 heterotetramer. The paired KT2440 moaD/moaE genes are consistent with this. No KT2440 complex has been isolated, so this is a family-level inference.
Supporting Evidence:
file:PSEPK/moaE/moaE-uniprot.txt
DR Pfam; PF02391; MoaE; 1.
file:ECOLI/moaE/moaE-uniprot.txt
SUBUNIT: Heterotetramer of 2 MoaD subunits and 2 MoaE subunits.

Core Functions

Catalytic subunit of molybdopterin synthase, using two thiocarboxylated MoaD sulfur carriers to convert cPMP to molybdopterin.

Molecular Function:
molybdopterin synthase activity
Directly Involved In:
Mo-molybdopterin cofactor biosynthetic process
In Complex:
molybdopterin synthase complex
Supporting Evidence:
  • file:PSEPK/moaE/moaE-uniprot.txt
    DR Pfam; PF02391; MoaE; 1.
  • file:PSEPK/moaE/moaE-uniprot.txt
    DR CDD; cd00756; MoaE; 1.
  • file:PSEPK/moaE/moaE-uniprot.txt
    DR InterPro; IPR003448; Mopterin_biosynth_MoaE.

References

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Suggested Experiments

Experiment: Reconstitute molybdopterin production with purified Q88NB8 and thiocarboxylated Q88NB9 and quantify substrate turnover.

Type: in vitro enzyme assay

Deep Research

OpenScientist

(moaE-deep-research-openscientist.md)

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📚 Additional Documentation

Notes

(moaE-notes.md)

moaE (Q88NB8, PP_1294) notes, P. putida KT2440

2026-11-10 completion pass

  • Review brought from DRAFT to COMPLETE, consistent with genes/ECOLI/moaE (P30749).
  • GO:0006777 and GO:0030366 IEA: ACCEPT (added missing support; Q88NB8's own CATALYTIC ACTIVITY,
    PATHWAY and SUBUNIT lines are ARBA predictions and are not quoted).
  • GO:0032324 (ARBA IEA): changed from MARK_AS_OVER_ANNOTATED to MODIFY -> GO:0006777. The term is
    true but general; GO:0006777 is its is_a child and is already carried.
  • NEW GO:1990140 (ISS from P30749) kept; support now quotes the PubMed-tied E. coli SUBUNIT line.
  • Dropped the self-citing GOA-table reference.
  • Core MF: GO:0030366 molybdopterin synthase activity.

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