pqqB encodes a metallo-beta-lactamase-fold, non-heme iron hydroxylase in pyrroloquinoline quinone (PQQ) biosynthesis. PqqB is inferred to catalyze oxygen-insertion chemistry on a PqqA-derived pathway intermediate, helping form the quinone chemistry required for subsequent PqqC-dependent production of mature PQQ. The exact native substrate, product, and relationship to pathway-specific proteolysis remain incompletely resolved.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0018189 pyrroloquinoline quinone biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: This process annotation should be retained. PqqB is a conserved PQQ-pathway protein, and primary biochemical/structural work supports a PqqB hydroxylase role in maturation of PqqA-derived intermediates during PQQ biosynthesis. Reason: PqqB is required for the PQQ pathway; the more recent literature refines its role from possible precursor transport to hydroxylase chemistry within pyrroloquinoline quinone biosynthesis. Supporting Evidence: file:PSEPK/pqqB/pqqB-uniprot.txt PATHWAY: Cofactor biosynthesis; pyrroloquinoline quinone biosynthesis. file:PSEPK/pqqB/pqqB-goa.tsv GO:0018189 pyrroloquinoline quinone biosynthetic process PMID:30811189 strongly implicate PqqB as a novel non-heme hydroxylase file:PSEPK/pqqB/pqqB-deep-research-falcon.md PqqB is part of PQQ biosynthesis and is transcriptionally co-induced with neighboring pqq genes under antibiotic stress. file:PSEPK/pqqB/pqqB-deep-research-falcon.md PP_0379 is explicitly annotated as **pqqB** and is genomically adjacent to **pqqC (PP0378)** and **pqqA (PP0380)** |
| GO:0016705 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen | ISS PMID:30811189 Discovery of Hydroxylase Activity for PqqB Provides a Missin... | NEW | Summary: PqqB should have an oxygen-incorporating oxidoreductase molecular-function annotation. The available primary literature supports a non-heme hydroxylase activity, although GO currently lacks a PqqB-specific hydroxylase term. Reason: GO:0016705 is a broad current parent term for the conserved PqqB oxygenase/hydroxylase chemistry. The direct biochemical demonstration of iron-dependent hydroxylase activity was made on Methylorubrum extorquens AM1 PqqB (UniProtKB:Q49149; PMID:30811189), so Q49149 is the explicit with/from source for this KT2440 orthology inference, not evidence of a direct assay of Q88QV5. Falcon deep research independently corroborates the oxygenase-like molecular function from the metallo-beta-lactamase fold and a non-heme-oxygenase facial triad, while emphasizing that strain-specific kinetics for KT2440 PqqB remain unproven. Supporting Evidence: PMID:30811189 show that PqqB is a previously uncharacterized hydroxylase PMID:30811189 strongly implicate PqqB as a novel non-heme hydroxylase file:PSEPK/pqqB/pqqB-deep-research-falcon.md PqqB likely acts as a **non-heme metallo-oxygenase** in PQQ biosynthesis file:PSEPK/pqqB/pqqB-deep-research-falcon.md a motif typical of **non-heme metal-binding oxygenases**, supporting an oxygenase-like hypothesis |
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Download this section (compressed HTML)Q: What is the native PqqB substrate and metal/co-substrate requirement in KT2440: cross-linked Glu-Tyr peptide, a cleaved diamino acid intermediate, or a downstream hydroxylated product?
Experiment: Reconstitute KT2440 PqqA/PqqD/PqqE/PqqB reactions and track oxygen incorporation and hydroxylated intermediates by LC-MS using wild-type and active-site mutant PqqB.
Hypothesis: KT2440 PqqB catalyzes hydroxylation of a PqqA-derived cross-linked intermediate during PQQ biosynthesis.
Type: reconstituted pathway biochemistry
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Download this section (compressed HTML)MISCITED and are not propagated. The review and reusable module retain aLoading supporting content…
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