NaBBL_candidate_FOX2_4

UniProt ID: A0A1J6KAK0
Organism: Nicotiana attenuata
Review Status: DRAFT
Aliases:
FOX2_4 NaBBL
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Gene Description

NaBBL_candidate_FOX2_4 is another FOX2-branch BBL-family oxidoreductase candidate in Nicotiana attenuata. The late nicotine oxidation role of the BBL family is now secure, but FOX2_4 remains an unresolved paralog rather than a uniquely assigned pathway enzyme.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005773 vacuole
IEA
GO_REF:0000044 		KEEP AS NON CORE
Summary: Vacuolar localization is plausible but not a core claim.
Reason: Retain the annotation as contextual information while keeping the review focused on pathway and paralog assignment.
GO:0016491 oxidoreductase activity
IEA
GO_REF:0000002 		MARK AS OVER ANNOTATED
Summary: This is too generic relative to the current BBL-family pathway model.
Reason: BBL-family proteins now have a more specific late nicotine oxidation role than this parent term conveys.
Supporting Evidence:
file:NICAT/NaBBL_candidate_FOX2_4/NaBBL_candidate_FOX2_4-notes.md
The full preprint shows that a BBL-family enzyme functions as NicGS in the reconstructed nicotine synthase cascade and contributes the pathway's stereochemical control.
GO:0050660 flavin adenine dinucleotide binding
IEA
GO_REF:0000002 		ACCEPT
Summary: FAD binding is an appropriate cofactor annotation.
Reason: This is an informative and specific term for a BBL-family flavoprotein.
GO:0071949 FAD binding
IEA
GO_REF:0000002 		REMOVE
Summary: This term is redundant with GO:0050660.
Reason: Retain GO:0050660 as the preferred cofactor-binding term and remove the duplicate.
GO:0042179 nicotine biosynthetic process
IEA
GO_REF:0000041 		KEEP AS NON CORE
Summary: FOX2_4 remains a plausible nicotine-pathway paralog, but exact assignment is unresolved.
Reason: Family-level support is strong, yet the current data do not identify FOX2_4 as the uniquely correct attenuata BBL paralog.
Supporting Evidence:
file:NICAT/NaBBL_candidate_FOX2_4/NaBBL_candidate_FOX2_4-notes.md
For FOX2_4, the remaining problem is paralog identification inside the BBL family, not whether BBL biochemistry belongs in the nicotine core pathway.

Core Functions

FOX2_4 is a BBL-family FAD-linked oxidoreductase candidate for the late nicotine step, but it remains one of several unresolved attenuata paralogs.

Molecular Function:
oxidoreductase activity
Directly Involved In:
nicotine biosynthetic process
Supporting Evidence:
  • file:NICAT/NaBBL_candidate_FOX2_4/NaBBL_candidate_FOX2_4-notes.md
    The full preprint shows that a BBL-family enzyme functions as NicGS in the reconstructed nicotine synthase cascade and contributes the pathway's stereochemical control.

References

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Suggested Questions for Experts

Q: Does FOX2_4 have measurable NicGS-like activity, or is it a noncore duplicate within the BBL family?

Q: Does FOX2_4 differ from FOX2_2 in expression timing, tissue specificity, or substrate preference?

Suggested Experiments

Experiment: Test FOX2_4 in late-pathway reconstitution assays and compare activity with FOX1_2 and FOX2_2.

Hypothesis: FOX2_4 is a lower-priority but still biochemically testable BBL-family paralog.

Type: pathway reconstitution assay

Experiment: Profile metabolite consequences of FOX2_4 perturbation alone and in BBL-family combinations.

Hypothesis: FOX2_4 contributes redundantly rather than uniquely to late nicotine chemistry.

Type: genetics plus metabolite profiling

Deep Research

OpenAI

(NaBBL_candidate_FOX2_4-deep-research-openai.md)

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📚 Additional Documentation

Notes

(NaBBL_candidate_FOX2_4-notes.md)

NaBBL_candidate_FOX2_4 Notes

  • The full preprint shows that a BBL-family enzyme functions as NicGS in the reconstructed nicotine synthase cascade and contributes the pathway's stereochemical control. [file:projects/NICOTINE_BIOSYNTHESIS/biorxiv-nicotine-glucosylation-notes.md "BBLa = NicGS, an (S)-nicotine glucoside synthase that drives pathway stereoselectivity"; "removing BBL/NicGS reduces nicotine and leaves residual racemic product"]
  • For FOX2_4, the remaining problem is paralog identification inside the BBL family, not whether BBL biochemistry belongs in the nicotine core pathway. [file:projects/NICOTINE_BIOSYNTHESIS/biorxiv-nicotine-glucosylation-notes.md "For the NICAT project, this paper is therefore strongest for pathway-role assignment and weakest for exact paralog/accession resolution."]

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