NaBBL1_candidate_FOX1_0 is a BBL-family FAD-linked oxidoreductase and a plausible NICAT late-pathway nicotine candidate. The recent glucosylation paper makes BBL-family involvement in the late nicotine step secure, but it does not single out FOX1_0 as the uniquely correct attenuata paralog.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0005773
vacuole
|
IEA
GO_REF:0000044 |
KEEP AS NON CORE |
Summary: Vacuolar localization is plausible and should be retained as non-core context.
Reason: UniProt supports vacuolar localization, but the main review question is which BBL paralog carries the late nicotine chemistry.
Supporting Evidence:
file:NICAT/NaBBL1_candidate_FOX1_0/NaBBL1_candidate_FOX1_0-uniprot.txt
CC -!- SUBCELLULAR LOCATION: Vacuole {ECO:0000256|ARBA:ARBA00004116}.
|
|
GO:0016491
oxidoreductase activity
|
IEA
GO_REF:0000002 |
MARK AS OVER ANNOTATED |
Summary: This term is true but too generic for the current BBL-family model.
Reason: The BBL family is now tied to a specific late oxidative step in nicotine synthesis, so the parent oxidoreductase term is no longer the most useful annotation.
Supporting Evidence:
file:NICAT/NaBBL1_candidate_FOX1_0/NaBBL1_candidate_FOX1_0-notes.md
The full preprint redefines BBLa as NicGS, the BBL-family enzyme that imposes stereoselective late-pathway chemistry in the nicotine synthase cascade, and supports that assignment with product-bound structural data.
|
|
GO:0050660
flavin adenine dinucleotide binding
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: FAD binding is an appropriate cofactor annotation for this BBL-family protein.
Reason: BBL-family late oxidases are flavoproteins, and UniProt explicitly assigns FAD cofactor use.
|
|
GO:0071949
FAD binding
|
IEA
GO_REF:0000002 |
REMOVE |
Summary: This is redundant with GO:0050660 and does not add information.
Reason: Keep the more standard GO:0050660 flavin adenine dinucleotide binding term and drop the redundant duplicate.
|
|
GO:0042179
nicotine biosynthetic process
|
IEA
GO_REF:0000041 |
KEEP AS NON CORE |
Summary: FOX1_0 remains a plausible nicotine-pathway paralog, but not the uniquely resolved BBL copy.
Reason: BBL-family pathway involvement is now strong, yet the exact attenuata paralog assignment remains unresolved across the FOX candidates.
Supporting Evidence:
file:NICAT/NaBBL1_candidate_FOX1_0/NaBBL1_candidate_FOX1_0-notes.md
For FOX1_0, that means the open question is paralog identity within the BBL family, not whether a BBL-like late oxidase matters in the pathway.
|
Q: Is FOX1_0 catalytically active in the NicGS-like late oxidation step, or is it a noncore BBL-family duplicate?
Q: How does FOX1_0 compare with FOX1_2 and the FOX2 paralogs in root expression and metabolite-linked phenotypes?
Experiment: Reconstitute the late nicotine pathway with FOX1_0 in place of the tobacco BBL/NicGS enzyme and test formation of stereoselective nicotine intermediates.
Hypothesis: FOX1_0 is less effective than the leading BBL anchor but may retain detectable late-pathway activity.
Type: pathway reconstitution assay
Experiment: Knock down FOX1_0 singly and in combination with other BBL-like paralogs and measure nicotine stereochemistry and intermediate accumulation.
Hypothesis: FOX1_0 contributes redundantly or secondarily within the BBL paralog set.
Type: combinatorial genetics plus metabolite profiling
The gene NaBBL1_candidate_FOX1_0 in Nicotiana attenuata encodes a flavin-dependent oxidoreductase, as indicated by its UniProt accession number A0A1J6JGR6. This protein is characterized by domains such as the Berberine Bridge Enzyme (BBE) domain (IPR012951) and the FAD-binding PCMH domain (IPR016166), suggesting its role in oxidation-reduction processes.
Protein Family and Domains
The presence of the BBE domain aligns the protein with the BBE-like enzyme family, known for catalyzing oxidation reactions involving alkaloid biosynthesis. The FAD-binding PCMH domain indicates the protein's reliance on flavin adenine dinucleotide (FAD) as a cofactor, essential for its oxidoreductase activity.
Biological Function and Localization
While specific studies on NaBBL1_candidate_FOX1_0 are limited, insights can be drawn from related proteins. In Arabidopsis thaliana, the flavin-dependent monooxygenase FMO1 is crucial for systemic acquired resistance, a defense mechanism against pathogens (pmc.ncbi.nlm.nih.gov). This suggests that NaBBL1_candidate_FOX1_0 may play a role in plant defense responses.
Additionally, the protein's association with alkaloid metabolism implies its involvement in the biosynthesis of secondary metabolites, which are vital for plant defense and adaptation. The presence of a signal peptide suggests that the protein is directed to specific cellular compartments, potentially the vacuole, where it may participate in metabolite storage or detoxification processes.
Inference from Domain and Family Information
Given the protein's domains and family associations, it is likely involved in oxidation-reduction reactions pertinent to alkaloid biosynthesis. These processes are integral to the plant's defense mechanisms and adaptation strategies. The exact substrates and reactions catalyzed by NaBBL1_candidate_FOX1_0 remain to be elucidated through experimental studies.
Conclusion
In summary, NaBBL1_candidate_FOX1_0 in Nicotiana attenuata is a flavin-dependent oxidoreductase potentially involved in alkaloid biosynthesis and plant defense mechanisms. Its precise function and role within cellular pathways warrant further investigation to fully understand its contributions to the plant's physiology and adaptation.
id: A0A1J6JGR6
gene_symbol: NaBBL1_candidate_FOX1_0
product_type: PROTEIN
status: DRAFT
aliases:
- FOX1_0
- NaBBL1
taxon:
id: NCBITaxon:49451
label: Nicotiana attenuata
description: >-
NaBBL1_candidate_FOX1_0 is a BBL-family FAD-linked oxidoreductase and a
plausible NICAT late-pathway nicotine candidate. The recent glucosylation paper
makes BBL-family involvement in the late nicotine step secure, but it does not
single out FOX1_0 as the uniquely correct attenuata paralog.
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with GO terms
findings: []
- id: GO_REF:0000041
title: Gene Ontology annotation based on UniPathway vocabulary mapping
findings: []
- id: GO_REF:0000044
title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
findings: []
- id: file:NICAT/NaBBL1_candidate_FOX1_0/NaBBL1_candidate_FOX1_0-uniprot.txt
title: UniProt entry A0A1J6JGR6 for Nicotiana attenuata FOX1_0
findings:
- statement: FOX1_0 is a BBL-family FAD-linked oxidoreductase associated with nicotine biosynthesis
supporting_text: Involved in the biosynthesis of pyridine alkaloid natural products, leading mainly to the production of anabasine, anatabine, nicotine and nornicotine ... Catalyzes a late oxidation step subsequent to the pyridine ring condensation reaction in the biosynthesis of alkaloids.
reference_section_type: DATABASE_ENTRY
- statement: UniProt places FOX1_0 in the vacuole and assigns FAD cofactor use
supporting_text: 'CC -!- SUBCELLULAR LOCATION: Vacuole {ECO:0000256|ARBA:ARBA00004116}.'
reference_section_type: DATABASE_ENTRY
- id: file:NICAT/NaBBL1_candidate_FOX1_0/NaBBL1_candidate_FOX1_0-notes.md
title: NaBBL1 FOX1_0 candidate notes
findings:
- statement: BBL-family late-pathway biology is secure for FOX1_0-level paralog review
supporting_text: The full preprint redefines BBLa as NicGS, the BBL-family enzyme that imposes stereoselective late-pathway chemistry in the nicotine synthase cascade, and supports that assignment with product-bound structural data.
reference_section_type: LITERATURE_REVIEW
- statement: FOX1_0 remains a paralog-resolution candidate rather than a settled single-copy assignment
supporting_text: For FOX1_0, that means the open question is paralog identity within the BBL family, not whether a BBL-like late oxidase matters in the pathway.
reference_section_type: LITERATURE_REVIEW
existing_annotations:
- term:
id: GO:0005773
label: vacuole
evidence_type: IEA
original_reference_id: GO_REF:0000044
review:
summary: Vacuolar localization is plausible and should be retained as non-core context.
action: KEEP_AS_NON_CORE
reason: >-
UniProt supports vacuolar localization, but the main review question is
which BBL paralog carries the late nicotine chemistry.
supported_by:
- reference_id: file:NICAT/NaBBL1_candidate_FOX1_0/NaBBL1_candidate_FOX1_0-uniprot.txt
supporting_text: 'CC -!- SUBCELLULAR LOCATION: Vacuole {ECO:0000256|ARBA:ARBA00004116}.'
reference_section_type: DATABASE_ENTRY
- term:
id: GO:0016491
label: oxidoreductase activity
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: This term is true but too generic for the current BBL-family model.
action: MARK_AS_OVER_ANNOTATED
reason: >-
The BBL family is now tied to a specific late oxidative step in nicotine
synthesis, so the parent oxidoreductase term is no longer the most useful
annotation.
supported_by:
- reference_id: file:NICAT/NaBBL1_candidate_FOX1_0/NaBBL1_candidate_FOX1_0-notes.md
supporting_text: The full preprint redefines BBLa as NicGS, the BBL-family enzyme that imposes stereoselective late-pathway chemistry in the nicotine synthase cascade, and supports that assignment with product-bound structural data.
reference_section_type: LITERATURE_REVIEW
- term:
id: GO:0050660
label: flavin adenine dinucleotide binding
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: FAD binding is an appropriate cofactor annotation for this BBL-family protein.
action: ACCEPT
reason: >-
BBL-family late oxidases are flavoproteins, and UniProt explicitly assigns
FAD cofactor use.
- term:
id: GO:0071949
label: FAD binding
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: This is redundant with GO:0050660 and does not add information.
action: REMOVE
reason: >-
Keep the more standard GO:0050660 flavin adenine dinucleotide binding term
and drop the redundant duplicate.
- term:
id: GO:0042179
label: nicotine biosynthetic process
evidence_type: IEA
original_reference_id: GO_REF:0000041
review:
summary: FOX1_0 remains a plausible nicotine-pathway paralog, but not the uniquely resolved BBL copy.
action: KEEP_AS_NON_CORE
reason: >-
BBL-family pathway involvement is now strong, yet the exact attenuata paralog
assignment remains unresolved across the FOX candidates.
supported_by:
- reference_id: file:NICAT/NaBBL1_candidate_FOX1_0/NaBBL1_candidate_FOX1_0-notes.md
supporting_text: For FOX1_0, that means the open question is paralog identity within the BBL family, not whether a BBL-like late oxidase matters in the pathway.
reference_section_type: LITERATURE_REVIEW
core_functions:
- molecular_function:
id: GO:0016491
label: oxidoreductase activity
directly_involved_in:
- id: GO:0042179
label: nicotine biosynthetic process
description: >-
FOX1_0 is a BBL-family FAD-linked oxidoreductase candidate for the late
nicotine-pathway oxidation step, but it remains one of several unresolved
paralogs.
supported_by:
- reference_id: file:NICAT/NaBBL1_candidate_FOX1_0/NaBBL1_candidate_FOX1_0-notes.md
supporting_text: The full preprint redefines BBLa as NicGS, the BBL-family enzyme that imposes stereoselective late-pathway chemistry in the nicotine synthase cascade, and supports that assignment with product-bound structural data.
reference_section_type: LITERATURE_REVIEW
proposed_new_terms: []
suggested_questions:
- question: Is FOX1_0 catalytically active in the NicGS-like late oxidation step, or is it a noncore BBL-family duplicate?
- question: How does FOX1_0 compare with FOX1_2 and the FOX2 paralogs in root expression and metabolite-linked phenotypes?
suggested_experiments:
- description: Reconstitute the late nicotine pathway with FOX1_0 in place of the tobacco BBL/NicGS enzyme and test formation of stereoselective nicotine intermediates.
experiment_type: pathway reconstitution assay
hypothesis: FOX1_0 is less effective than the leading BBL anchor but may retain detectable late-pathway activity.
- description: Knock down FOX1_0 singly and in combination with other BBL-like paralogs and measure nicotine stereochemistry and intermediate accumulation.
experiment_type: combinatorial genetics plus metabolite profiling
hypothesis: FOX1_0 contributes redundantly or secondarily within the BBL paralog set.