NaBGL2_candidate_BGLU18_1 is the best current NICAT mapping for the beta-GD2-like homeologous late hydrolase in the nicotine pathway. The evidence is somewhat less direct than for the beta-GD1 anchor, but the pathway paper and mapping pass together keep BGLU18_1 as the leading attenuata candidate for the second beta-GD-like copy.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0004553
hydrolase activity, hydrolyzing O-glycosyl compounds
|
IEA
GO_REF:0000120 |
MODIFY |
Summary: This broad hydrolase term should be narrowed to beta-glucosidase activity.
Reason: GO:0008422 is the more informative GH1 activity term for this candidate.
Proposed replacements:
beta-glucosidase activity
|
|
GO:0005975
carbohydrate metabolic process
|
IEA
GO_REF:0000002 |
MARK AS OVER ANNOTATED |
Summary: This generic process term is too broad for the pathway-focused review.
Reason: The important curation question is whether this copy participates in late nicotine-pathway glucoside hydrolysis, not generic carbohydrate metabolism.
|
|
GO:0008422
beta-glucosidase activity
|
IEA
GO_REF:0000118 |
ACCEPT |
Summary: Beta-glucosidase activity is the appropriate core molecular-function annotation.
Reason: UniProt and GH1 family assignment support beta-glucosidase chemistry for this beta-GD2-like candidate.
Supporting Evidence:
file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-uniprot.txt
DR GO; GO:0008422; F:beta-glucosidase activity; IEA:TreeGrafter.
|
|
GO:0042179
nicotine biosynthetic process
|
TAS
file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-notes.md |
NEW |
Summary: BGLU18_1 should be added as a plausible homeologous nicotine-pathway hydrolase candidate.
Reason: The pathway paper retains a beta-GD2-like homeologous cluster, and the mapping pass now identifies BGLU18_1 as the best current attenuata ortholog.
Supporting Evidence:
file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-notes.md
The 2026-04-05 mapping dive assigns NaBGL2 to BGLU18_1 / A0A314KWB2 as the best current sequence-backed NICAT ortholog to tobacco beta-GD2.
|
Q: Does A0A314KWB2 function as a true beta-GD2-like nicotine glucoside hydrolase in Nicotiana attenuata, or is it a partially diverged homeolog?
Q: How much functional redundancy exists between the BGLU18_1 and BGLU18_6 copies in roots?
Experiment: Compare BGLU18_1 and BGLU18_6 side by side in late-pathway glucoside hydrolysis assays.
Hypothesis: BGLU18_1 is catalytically competent but weaker or differently tuned than the primary BGLU18_6 anchor.
Type: comparative biochemical assay
Experiment: Generate single and double disruptions of the two BGLU18 candidates and quantify glucosylated late intermediates and nicotine accumulation.
Hypothesis: The two BGLU18 copies have overlapping but non-identical contributions to late nicotine-pathway flux.
Type: genetics plus metabolite profiling
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
The UniProt target A0A314KWB2 is annotated as a Nicotiana attenuata (coyote tobacco) glycoside hydrolase family 1 (GH1) beta-glucosidase with gene name BGLU18_1 (ORF: A4A49_09974) and conserved GH1 domains. However, despite targeted literature searches for A0A314KWB2, A4A49_09974, and BGLU18_1 in N. attenuata, no primary paper directly characterizing this specific gene/protein (substrate specificity, kinetics, localization, pathway placement, mutant/overexpression phenotypes) was retrieved. Therefore, the most rigorous current annotation is inference-based, grounded in (i) GH1 beta-glucosidase family mechanisms and known biological roles in plants and (ii) N. attenuata specialized-metabolism context, while explicitly avoiding conflation with similarly named genes in other species (e.g., Arabidopsis AtBGLU18). (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2, li2022harmonizingbiosynthesiswith pages 3-4)
Verified identity to use for annotation (from the user-supplied UniProt record):
- Organism: Nicotiana attenuata (coyote tobacco) (target organism for all claims in this report)
- UniProt accession: A0A314KWB2
- Protein description: “Beta-glucosidase 18” (SubName)
- Gene/ORF names: BGLU18_1, ORF A4A49_09974
- Family / domains: GH1 beta-glucosidase (glycosyl hydrolase family 1)
Ambiguity note: “BGLU18” is widely used for other species’ GH1 beta-glucosidases (notably Arabidopsis AtBGLU18). These homologs provide useful functional analogies, but they are not direct evidence for the N. attenuata protein A0A314KWB2. (yang2024genomewideidentificationand pages 1-2)
Plant beta-glucosidases (EC 3.2.1.21) are glycosidases that cleave glycosidic bonds to release beta-D-glucose and an aglycone/ligand. In plants, many BGLUs belong to glycoside hydrolase family 1 (GH1) and are considered functionally diverse across metabolism and stress responses. (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2)
Recent plant GH1 family syntheses describe a canonical GH1 architecture and mechanism: GH1 BGLUs typically adopt a (β/α)8 barrel (TIM barrel) fold; the active site contains two catalytic carboxylates that perform acid/base catalysis and nucleophilic attack in a two-step retaining (double-displacement) mechanism. This mechanism-level knowledge strongly supports that A0A314KWB2 is a retaining beta-glycosidase. (yang2024genomewideidentificationand pages 1-2)
Across plants, GH1 BGLUs are repeatedly implicated in:
- Activation of glycosylated phytohormones (e.g., deconjugation/hydrolysis of hormone glucosides/esters)
- Defense chemistry (activation or turnover of stored glycosides)
- Cell wall remodeling / oligosaccharide hydrolysis
- Secondary metabolism (release of aglycones involved in phenylpropanoid/alkaloid/cyanogenic pathways)
- Microbe/insect interactions
These are family-level expectations; specific substrate selectivity is usually enzyme- and lineage-specific. (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2)
Because A0A314KWB2 is assigned to GH1, the strongest inference is:
- Enzymatic activity: retaining beta-glucosidase / beta-D-glucoside glucohydrolase activity
- Reaction type: hydrolysis of a beta-linked glucosyl moiety from a glucoside substrate → β-D-glucose + aglycone/ligand
This is a high-confidence family-level annotation, but the native substrate(s) in N. attenuata cannot be asserted from the retrieved evidence. (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2)
Cannot be claimed from retrieved evidence:
- That BGLU18_1 hydrolyzes ABA-GE, HGL-DTGs, coumarin glucosides, cyanogenic glucosides, or monolignol glucosides in N. attenuata.
What can be inferred as plausible candidate substrate classes (hypothesis-level):
- Phytohormone conjugates (e.g., ABA conjugates), based on GH1 precedent in other plants (AtBGLU18/10)
- Specialized metabolite glucosides that require hydrolysis for activation/turnover
- Oligosaccharides/cell-wall-related glucosides
These are plausible because they match recurring GH1 functional themes, but require direct N. attenuata experimental verification. (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2)
A highly relevant N. attenuata-focused review summarizes that 17-hydroxygeranyllinalool diterpene glycosides (HGL-DTGs) are stored as glycosides and undergo complex post-ingestive modifications after herbivore feeding. Importantly, in this system, the defensive “activation” is described as differing from classic “glucoside + plant glucosidase detonator” models: HGL-DTG defensive function is mediated by post-ingestive hydroxylation processes in insect guts, and the plant-derived enzyme(s) responsible for the non-specific hydroxylation activation remain unresolved. (li2022harmonizingbiosynthesiswith pages 3-4, li2022harmonizingbiosynthesiswith pages 4-6)
This matters for BGLU18_1 annotation: it cautions against assuming a plant GH1 beta-glucosidase is the key activator (“detonator”) of HGL-DTGs in N. attenuata, at least for the Manduca interaction described. (li2022harmonizingbiosynthesiswith pages 3-4)
Multiple sources describe that, in Manduca herbivores, a midgut-expressed beta-glucosidase (BG1) is induced by ingestion of lyciumoside IV (a major HGL-DTG) and mediates detoxification via deglucosylation. This is explicitly an insect enzyme role, not evidence for the plant enzyme A0A314KWB2. (poreddy2016probingtheherbivores pages 14-38, li2022harmonizingbiosynthesiswith pages 4-6)
Nevertheless, these results provide ecological and biochemical context in which plant glucosides and glucosidases can shape defense and counter-defense.
No direct localization data (e.g., GFP fusion, immunolocalization, organelle proteomics) were found for N. attenuata BGLU18_1 (A0A314KWB2).
However, recent GH1 syntheses emphasize that GH1 BGLUs in plants can localize to diverse compartments. Examples given include ER-localized AtBGLU18 and vesicle-localized AtBGLU10, both implicated in ABA-GE hydrolysis, as well as chloroplast-localized Os3BGLU6. This supports the general point that subcellular localization is variable and must be measured; it cannot be reliably inferred solely from the family name. (yang2024genomewideidentificationand pages 1-2)
Because gene-specific work for N. attenuata BGLU18_1 was not retrieved, the “latest research” component is presented as state-of-the-field GH1/BGLU advances relevant to functional inference:
Two 2024 genome-wide studies (buckwheat; alfalfa) summarize conserved GH1 features (motifs/mechanism) and reinforce that large GH1 BGLU repertoires are associated with diverse biological roles and stress responsiveness:
- Buckwheat GH1 analysis reiterates GH1 mechanism and provides examples tying BGLUs to phytohormone activation (ABA release from ABA-GE by AtBGLU18/10) and to stress responses, with subcellular localization examples spanning ER/vesicles/chloroplast. (yang2024genomewideidentificationand pages 1-2)
- Alfalfa GH1 analysis frames GH1 BGLUs as mediators of development and stress response, often through phytohormone activation and defensive-chemical turnover; it highlights broad roles in defense, hormone activation, and secondary metabolism. (kong2024genomewideidentificationand pages 1-2)
These studies are relevant for annotation of A0A314KWB2 because they provide up-to-date consensus descriptions of GH1 enzyme function and biological embedding, but they do not add N. attenuata-specific substrate claims. (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2)
A clear real-world/field-relevant implementation present in the retrieved evidence is plant-mediated RNAi deployed in N. attenuata to silence insect midgut detoxification genes under field conditions.
In a 2017 field study, transgenic N. attenuata expressing dsRNA constructs targeting Manduca genes CYP6B46 (nicotine response) and BG1 (lyciumoside-IV response) successfully reduced homologous transcripts in wild M. quinquemaculata, supporting PMRi as a viable crop-protection strategy for congeneric pests. (poreddy2017plantmediatedrnaisilences pages 1-2, poreddy2017plantmediatedrnaisilences pages 2-5)
This is not a use of plant BGLU18_1 per se, but it is a concrete example where beta-glucosidase biology (BG1) is exploited for pest management and where N. attenuata serves as an ecological model and biotechnological platform. (poreddy2017plantmediatedrnaisilences pages 1-2)
Although no kinetics or expression data exist for A0A314KWB2 in the retrieved set, several quantitative results illuminate the defense context in the correct N. attenuata system:
PMRi lines reduced M. quinquemaculata midgut transcripts by approximately 90% (CYP6B46) and 80% (BG1) in nature (field), showing strong silencing without affecting the closest off-target transcripts. (poreddy2017plantmediatedrnaisilences pages 1-2)
In dissertation-derived evidence (Manduca on N. attenuata):
- Midgut extracts from BG1-silenced larvae produced 55% less RGHGL (a partially deglycosylated lyciumoside IV product).
- Silenced larvae excreted 40% more lyciumoside IV and 70% less RGHGL than controls.
These data support a mechanistic role for insect BG1 in HGL-DTG detoxification. (poreddy2016probingtheherbivoresb pages 72-74, poreddy2016probingtheherbivores pages 72-74)
Total HGL-DTG concentrations increased significantly under herbivory in N. attenuata (reported as F1,4 = 36.88, P ≤ 0.0037; n = 3), with increases contributed by lyciumoside IV and related DTGs. (poreddy2016probingtheherbivores pages 14-38, poreddy2016probingtheherbivoresc pages 14-38)
A 2022 Natural Product Reports highlight by Li, Baldwin & Li argues that for many plant specialized metabolites, the biologically active/toxic forms can emerge from post-ingestive modifications, and that N. attenuata HGL-DTGs do not fit the simplest “plant glycoside + plant glucosidase detonator” paradigm. This synthesis supports a conservative interpretation: even though BGLU18_1 is a GH1 beta-glucosidase, it should not be automatically assigned as the HGL-DTG ‘detonator’ enzyme without direct evidence. (li2022harmonizingbiosynthesiswith pages 3-4, li2022harmonizingbiosynthesiswith pages 4-6)
The following table separates direct evidence for NaBGLU18_1 from indirect inference and related-system data, with URLs and dates.
| Evidence type | Claim (reaction/substrate/localization/pathway) | Supporting source (paper title) | Publication date/year | URL/DOI | Notes/limitations |
|---|---|---|---|---|---|
| Direct evidence status for NaBGLU18_1 / A0A314KWB2 | No direct biochemical or genetic characterization of Nicotiana attenuata BGLU18_1 was identified in the retrieved literature; therefore specific substrate, reaction, pathway role, and localization remain unverified experimentally for this exact protein. (poreddy2016probingtheherbivores pages 14-38, yang2024genomewideidentificationand pages 1-2, li2022harmonizingbiosynthesiswith pages 3-4) | Multiple retrieved sources surveyed; no paper directly characterizing A0A314KWB2/BGLU18_1 found | 2016-2024 | UniProt accession supplied by user: https://www.uniprot.org/uniprotkb/A0A314KWB2 | Critical limitation: annotation must rely on UniProt family/domain assignment and indirect GH1 knowledge unless future organism-specific evidence appears. |
| Indirect GH1 family/domain inference | A0A314KWB2 belongs to glycoside hydrolase family 1 (GH1) beta-glucosidases, so the most defensible core inference is that it is a retaining beta-glycosidase acting on glucosidic substrates, releasing beta-D-glucose plus an aglycone/ligand. (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2) | Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum; Genome-wide identification and expression analysis of the glycosyl hydrolase family 1 genes in Medicago sativa revealed their potential roles in response to multiple abiotic stresses | 2024; 2024 | https://doi.org/10.1186/s12870-024-05919-3 ; https://doi.org/10.1186/s12864-023-09918-w | Indirect only; family-level prediction does not establish the natural substrate of NaBGLU18_1. |
| Indirect GH1 catalytic mechanism | Plant GH1 BGLUs typically have a classical (beta/alpha)8 barrel and two catalytic carboxylates operating by a retaining double-displacement mechanism. (yang2024genomewideidentificationand pages 1-2) | Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum | 2024 | https://doi.org/10.1186/s12870-024-05919-3 | Mechanistic inference is strong for GH1 enzymes but was not experimentally shown for A0A314KWB2. |
| Indirect substrate-spectrum inference | Plant GH1 BGLUs can hydrolyze glucosides involved in cyanohydrin, alkaloid, phenylpropanoid, defense-compound, and phytohormone metabolism; many also function in cell wall remodeling, scent release, and microbe/insect interactions. (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2) | Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum; Genome-wide identification and expression analysis of the glycosyl hydrolase family 1 genes in Medicago sativa revealed their potential roles in response to multiple abiotic stresses | 2024; 2024 | https://doi.org/10.1186/s12870-024-05919-3 ; https://doi.org/10.1186/s12864-023-09918-w | Broad family properties only; they do not prove whether NaBGLU18_1 prefers hormone conjugates, defense glycosides, or other glucosides. |
| Indirect hormone-related functional analogy | Some plant GH1 members, notably AtBGLU18 and AtBGLU10, hydrolyze ABA-glucose ester (ABA-GE) to release active abscisic acid (ABA), linking GH1 enzymes to stress signaling. (yang2024genomewideidentificationand pages 1-2) | Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum | 2024 | https://doi.org/10.1186/s12870-024-05919-3 | Important analogy because the target symbol contains “BGLU18”, but this is not evidence that Nicotiana attenuata BGLU18_1 is an ABA-GE hydrolase. Gene symbols are potentially misleading across species. |
| Indirect localization analogy | Reported localizations for characterized plant GH1 BGLUs include endoplasmic reticulum for AtBGLU18, vesicles for AtBGLU10, and chloroplast for Os3BGLU6. (yang2024genomewideidentificationand pages 1-2) | Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum | 2024 | https://doi.org/10.1186/s12870-024-05919-3 | Localization of NaBGLU18_1 remains unknown; these examples only show that GH1 BGLUs occupy diverse intracellular compartments. |
| Indirect stress-pathway inference | GH1 BGLUs are frequently implicated in biotic/abiotic stress responses and can contribute by activating stored defensive chemicals or phytohormone conjugates. (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2) | Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in Fagopyrum tataricum; Genome-wide identification and expression analysis of the glycosyl hydrolase family 1 genes in Medicago sativa revealed their potential roles in response to multiple abiotic stresses | 2024; 2024 | https://doi.org/10.1186/s12870-024-05919-3 ; https://doi.org/10.1186/s12864-023-09918-w | This supports a stress-related annotation at family level, but not a specific pathway assignment for A0A314KWB2. |
| Context from Nicotiana attenuata defense chemistry (not direct NaBGLU18_1 evidence) | In N. attenuata, 17-hydroxygeranyllinalool diterpene glycosides (HGL-DTGs) are major defense metabolites, but their defensive activation is described as involving post-ingestive hydroxylation rather than a demonstrated plant GH1 beta-glucosidase cleavage step. (li2022harmonizingbiosynthesiswith pages 3-4, li2022harmonizingbiosynthesiswith pages 4-6) | Harmonizing biosynthesis with post-ingestive modifications to understand the ecological functions of plant natural products | May 2022 | https://doi.org/10.1039/d2np00019a | Highly relevant to N. attenuata specialized metabolism; however, this paper explicitly shifts emphasis away from assuming a plant beta-glucosidase trigger for HGL-DTG activation. |
| Context from N. attenuata HGL-DTG pathway | Prior to herbivory, geranyllinalool is hydroxylated by NaCYP736As, glycosylated by UGT74P, and later malonylated; disruption of these steps causes accumulation of autotoxic intermediates. (li2022harmonizingbiosynthesiswith pages 3-4) | Harmonizing biosynthesis with post-ingestive modifications to understand the ecological functions of plant natural products | May 2022 | https://doi.org/10.1039/d2np00019a | Relevant pathway background for N. attenuata; no direct role for NaBGLU18_1 shown. |
| Context from insect-plant interaction | In Manduca sexta, only the glucose at C-17 of HGL-DTGs is removed by an insect midgut beta-glucosidase, representing a detoxification step for the herbivore rather than a demonstrated plant enzymatic step. (li2022harmonizingbiosynthesiswith pages 4-6) | Harmonizing biosynthesis with post-ingestive modifications to understand the ecological functions of plant natural products | May 2022 | https://doi.org/10.1039/d2np00019a | Important limitation: these beta-glucosidase data concern the herbivore, not NaBGLU18_1. |
| Quantitative, non-target comparison from Manduca PMRi | Plant-mediated RNAi lines targeting larval genes reduced M. quinquemaculata CYP6B46 and BG1 transcripts by about 90% and 80%, respectively, showing strong silencing of insect detoxification genes on transgenic N. attenuata plants. (poreddy2017plantmediatedrnaisilences pages 1-2) | Plant-mediated RNAi silences midgut-expressed genes in congeneric lepidopteran insects in nature | Nov 2017 | https://doi.org/10.1186/s12870-017-1149-5 | Included because requested and relevant to HGL-DTG context, but this is not evidence about plant NaBGLU18_1 function. |
| Quantitative, non-target comparison from Manduca PMRi and dissertation evidence | PMRi studies/dissertation report ca. 90% CYP6B46 and ca. 75% BG1 transcript reduction in larval midguts, with 98% and 96% sequence similarity between PMRi constructs and homologs. (poreddy2016probingtheherbivoresc pages 14-38, poreddy2017plantmediatedrnaisilences pages 2-5) | Probing the herbivores responses to plant defenses using plant-mediated RNAi; Plant-mediated RNAi silences midgut-expressed genes in congeneric lepidopteran insects in nature | 2016; 2017 | DOI unavailable in retrieved text for dissertation; https://doi.org/10.1186/s12870-017-1149-5 | Values vary slightly by source/reporting context (75% vs 80% BG1 reduction). These are insect-gene silencing data, not NaBGLU18_1 measurements. |
| Quantitative metabolite effects in insect BG1 silencing | Midgut extracts from beta-glucosidase1-silenced larvae produced 55% less RGHGL (partially deglycosylated lyciumoside IV product); silenced larvae excreted 40% more lyciumoside IV and 70% less RGHGL than controls. (poreddy2016probingtheherbivoresb pages 72-74, poreddy2016probingtheherbivores pages 72-74) | Probing the herbivores responses to plant defenses using plant-mediated RNAi | 2016 | DOI unavailable in retrieved text | Useful quantitative benchmark for HGL-DTG detoxification, but all measurements concern insect BG1 activity, not the plant protein A0A314KWB2. |
| Quantitative HGL-DTG induction in plant upon herbivory | Total HGL-DTG concentrations in N. attenuata leaves increased significantly after herbivory (F1,4 = 36.88, P <= 0.0037; n = 3), with contributions from lyciumoside IV, Nic1, and Nic2. (poreddy2016probingtheherbivores pages 14-38, poreddy2016probingtheherbivoresc pages 14-38) | Probing the herbivores responses to plant defenses using plant-mediated RNAi | 2016 | DOI unavailable in retrieved text | Demonstrates the defensive metabolite context in the correct organism, but does not identify NaBGLU18_1 as the responsible enzyme for any step. |
| Functional interpretation relevant to annotation | The safest current annotation for BGLU18_1 / A0A314KWB2 is therefore: putative GH1 beta-glucosidase with probable retaining glycosidase activity on an as-yet-unknown plant glucoside substrate; possible involvement in stress or specialized metabolism is plausible but unproven. (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2, li2022harmonizingbiosynthesiswith pages 3-4) | Family/domain and plant-defense context synthesized from retrieved sources | 2022-2024 | https://doi.org/10.1186/s12870-024-05919-3 ; https://doi.org/10.1186/s12864-023-09918-w ; https://doi.org/10.1039/d2np00019a | This is an inference-based functional annotation, explicitly distinct from direct experimental characterization. |
Table: This table distinguishes direct evidence for Nicotiana attenuata BGLU18_1 from indirect GH1 family knowledge and related N. attenuata defense literature. It is useful for functional annotation because it makes clear which claims are experimentally supported for the exact target and which remain inference-based.
Given the evidence available in this run, a safe, standards-aligned functional annotation for N. attenuata BGLU18_1 (A0A314KWB2) is:
- Protein family: GH1 beta-glucosidase (glycoside hydrolase family 1) (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2)
- Molecular function (high confidence, family-level): retaining beta-glucosidase acting on beta-D-glucosides to release beta-D-glucose + aglycone/ligand (yang2024genomewideidentificationand pages 1-2)
- Biological process (moderate confidence, family-level): likely participates in metabolism of glucosylated compounds in planta (hormone conjugates and/or specialized metabolite glucosides), potentially in stress-related contexts; specific pathway assignment requires direct evidence (yang2024genomewideidentificationand pages 1-2, kong2024genomewideidentificationand pages 1-2)
- Subcellular localization: unknown for this protein; GH1 BGLUs can be ER/vesicle/chloroplast localized in other plants, so localization should be experimentally determined for N. attenuata BGLU18_1 (yang2024genomewideidentificationand pages 1-2)
To meet the user’s stated needs (“primary function, substrate specificity, where it works”), the missing data for A0A314KWB2 are:
- Biochemical assays with candidate glucoside substrates (determine Km/kcat, specificity)
- Genetic perturbation in N. attenuata (CRISPR/RNAi/overexpression) with metabolomics to map pathway impact
- Subcellular localization experiments (fluorescent tagging, fractionation)
- Expression profiling across tissues/stresses/herbivory to connect to defense/hormone pathways
These are standard next steps precisely because GH1 family membership alone is not enough to uniquely assign a natural substrate in planta. (yang2024genomewideidentificationand pages 1-2, li2022harmonizingbiosynthesiswith pages 3-4)
References
(yang2024genomewideidentificationand pages 1-2): Haizhu Yang, Xin Yao, Weijiao Wu, Ailing He, Chao Ma, Sanwei Yang, and Jingjun Ruan. Genome-wide identification and gene expression pattern analysis of the glycoside hydrolase family 1 in fagopyrum tataricum. BMC Plant Biology, Dec 2024. URL: https://doi.org/10.1186/s12870-024-05919-3, doi:10.1186/s12870-024-05919-3. This article has 3 citations and is from a peer-reviewed journal.
(kong2024genomewideidentificationand pages 1-2): Haiming Kong, Jiaxing Song, Shihai Ma, Jing Yang, Zitong Shao, Qian Li, Zhongxing Li, Zhiguo Xie, Peizhi Yang, and Yuman Cao. Genome-wide identification and expression analysis of the glycosyl hydrolase family 1 genes in medicago sativa revealed their potential roles in response to multiple abiotic stresses. BMC Genomics, Jan 2024. URL: https://doi.org/10.1186/s12864-023-09918-w, doi:10.1186/s12864-023-09918-w. This article has 28 citations and is from a peer-reviewed journal.
(li2022harmonizingbiosynthesiswith pages 3-4): Jiancai Li, Ian T. Baldwin, and Dapeng Li. Harmonizing biosynthesis with post-ingestive modifications to understand the ecological functions of plant natural products. Natural Product Reports, 39:1383-1392, May 2022. URL: https://doi.org/10.1039/d2np00019a, doi:10.1039/d2np00019a. This article has 8 citations and is from a peer-reviewed journal.
(li2022harmonizingbiosynthesiswith pages 4-6): Jiancai Li, Ian T. Baldwin, and Dapeng Li. Harmonizing biosynthesis with post-ingestive modifications to understand the ecological functions of plant natural products. Natural Product Reports, 39:1383-1392, May 2022. URL: https://doi.org/10.1039/d2np00019a, doi:10.1039/d2np00019a. This article has 8 citations and is from a peer-reviewed journal.
(poreddy2016probingtheherbivores pages 14-38): S Poreddy. Probing the herbivores responses to plant defenses using plant-mediated rnai. Unknown journal, 2016.
(poreddy2017plantmediatedrnaisilences pages 1-2): Spoorthi Poreddy, Jiancai Li, and Ian T. Baldwin. Plant-mediated rnai silences midgut-expressed genes in congeneric lepidopteran insects in nature. BMC Plant Biology, Nov 2017. URL: https://doi.org/10.1186/s12870-017-1149-5, doi:10.1186/s12870-017-1149-5. This article has 59 citations and is from a peer-reviewed journal.
(poreddy2017plantmediatedrnaisilences pages 2-5): Spoorthi Poreddy, Jiancai Li, and Ian T. Baldwin. Plant-mediated rnai silences midgut-expressed genes in congeneric lepidopteran insects in nature. BMC Plant Biology, Nov 2017. URL: https://doi.org/10.1186/s12870-017-1149-5, doi:10.1186/s12870-017-1149-5. This article has 59 citations and is from a peer-reviewed journal.
(poreddy2016probingtheherbivoresb pages 72-74): S Poreddy. Probing the herbivores responses to plant defenses using plant-mediated rnai. Unknown journal, 2016.
(poreddy2016probingtheherbivores pages 72-74): S Poreddy. Probing the herbivores responses to plant defenses using plant-mediated rnai. Unknown journal, 2016.
(poreddy2016probingtheherbivoresc pages 14-38): S Poreddy. Probing the herbivores responses to plant defenses using plant-mediated rnai. Unknown journal, 2016.
A0A314KWB2 as BGLU18_1, a glycosyl hydrolase family 1 beta-glucosidase. [file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-uniprot.txt "DE SubName: Full=Beta-glucosidase 18"; "CC -!- SIMILARITY: Belongs to the glycosyl hydrolase 1 family."; "DR GO; GO:0008422; F:beta-glucosidase activity; IEA:TreeGrafter."]NaBGL2 to BGLU18_1 / A0A314KWB2 as the best current sequence-backed NICAT ortholog to tobacco beta-GD2. [file:projects/NICOTINE_BIOSYNTHESIS.md "NaBGL2 -> BGLU18_1 / A0A314KWB2"; "Tobacco beta-GD2 (Nitab4.5_0000031g0400) maps best to NIATv7_g09974, then to UniProt BGLU18_1."]id: A0A314KWB2
gene_symbol: NaBGL2_candidate_BGLU18_1
product_type: PROTEIN
status: DRAFT
aliases:
- BGLU18_1
- NaBGL2
taxon:
id: NCBITaxon:49451
label: Nicotiana attenuata
description: >-
NaBGL2_candidate_BGLU18_1 is the best current NICAT mapping for the beta-GD2-like
homeologous late hydrolase in the nicotine pathway. The evidence is somewhat
less direct than for the beta-GD1 anchor, but the pathway paper and mapping
pass together keep BGLU18_1 as the leading attenuata candidate for the second
beta-GD-like copy.
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with GO
terms
findings: []
- id: GO_REF:0000118
title: TreeGrafter-generated GO annotations
findings: []
- id: GO_REF:0000120
title: Combined Automated Annotation using Multiple IEA Methods
findings: []
- id: file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-uniprot.txt
title: UniProt entry A0A314KWB2 for Nicotiana attenuata BGLU18_1
findings:
- statement: BGLU18_1 is a glycosyl hydrolase family 1 beta-glucosidase
supporting_text: 'DE SubName: Full=Beta-glucosidase 18'
reference_section_type: DATABASE_ENTRY
- statement: UniProt assigns beta-glucosidase activity to BGLU18_1
supporting_text: 'DR GO; GO:0008422; F:beta-glucosidase activity; IEA:TreeGrafter.'
reference_section_type: DATABASE_ENTRY
- id: file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-notes.md
title: NaBGL2 BGLU18_1 candidate notes
findings:
- statement: beta-GD2 remains a pathway-relevant homeologous hydrolase candidate
supporting_text: The glucosylation preprint identifies a homeologous A622L-MATE2-beta-GD2 cluster alongside A622-MATE1-beta-GD1, which keeps a second beta-GD-like hydrolase in the pathway frame even though beta-GD1 is the more directly assayed late-step anchor.
reference_section_type: LITERATURE_REVIEW
- statement: BGLU18_1 is the best current sequence-backed NICAT ortholog to tobacco beta-GD2
supporting_text: The 2026-04-05 mapping dive assigns NaBGL2 to BGLU18_1 / A0A314KWB2 as the best current sequence-backed NICAT ortholog to tobacco beta-GD2.
reference_section_type: LITERATURE_REVIEW
- id: file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-deep-research-falcon.md
title: Deep research report on NaBGL2/BGLU18_1 (Falcon/Edison Scientific Literature)
findings:
- statement: No primary publication directly characterizes A0A314KWB2 / BGLU18_1;
the deep research supports a cautious GH1-family annotation (retaining beta-glucosidase,
conserved catalytic glutamates, TIM-barrel fold) and treats the attenuata
BGLU18_1 as the homeologous beta-GD2 candidate in the A622L-MATE2-beta-GD2
late nicotine-pathway cluster, alongside the better-characterized BGLU18_6
(beta-GD1) anchor.
existing_annotations:
- term:
id: GO:0004553
label: hydrolase activity, hydrolyzing O-glycosyl compounds
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: This broad hydrolase term should be narrowed to beta-glucosidase activity.
action: MODIFY
reason: >-
GO:0008422 is the more informative GH1 activity term for this candidate.
proposed_replacement_terms:
- id: GO:0008422
label: beta-glucosidase activity
- term:
id: GO:0005975
label: carbohydrate metabolic process
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: This generic process term is too broad for the pathway-focused review.
action: MARK_AS_OVER_ANNOTATED
reason: >-
The important curation question is whether this copy participates in late
nicotine-pathway glucoside hydrolysis, not generic carbohydrate metabolism.
- term:
id: GO:0008422
label: beta-glucosidase activity
evidence_type: IEA
original_reference_id: GO_REF:0000118
review:
summary: Beta-glucosidase activity is the appropriate core molecular-function annotation.
action: ACCEPT
reason: >-
UniProt and GH1 family assignment support beta-glucosidase chemistry for
this beta-GD2-like candidate.
supported_by:
- reference_id: file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-uniprot.txt
supporting_text: 'DR GO; GO:0008422; F:beta-glucosidase activity; IEA:TreeGrafter.'
reference_section_type: DATABASE_ENTRY
- term:
id: GO:0042179
label: nicotine biosynthetic process
evidence_type: TAS
original_reference_id: file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-notes.md
review:
summary: BGLU18_1 should be added as a plausible homeologous nicotine-pathway hydrolase candidate.
action: NEW
reason: >-
The pathway paper retains a beta-GD2-like homeologous cluster, and the
mapping pass now identifies BGLU18_1 as the best current attenuata ortholog.
supported_by:
- reference_id: file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-notes.md
supporting_text: The 2026-04-05 mapping dive assigns NaBGL2 to BGLU18_1 / A0A314KWB2 as the best current sequence-backed NICAT ortholog to tobacco beta-GD2.
reference_section_type: LITERATURE_REVIEW
core_functions:
- molecular_function:
id: GO:0008422
label: beta-glucosidase activity
directly_involved_in:
- id: GO:0042179
label: nicotine biosynthetic process
description: >-
BGLU18_1 is the leading current NICAT candidate for the homeologous beta-GD2-like
late hydrolase branch in nicotine biosynthesis.
supported_by:
- reference_id: file:NICAT/NaBGL2_candidate_BGLU18_1/NaBGL2_candidate_BGLU18_1-notes.md
supporting_text: The glucosylation preprint identifies a homeologous A622L-MATE2-beta-GD2 cluster alongside A622-MATE1-beta-GD1, which keeps a second beta-GD-like hydrolase in the pathway frame even though beta-GD1 is the more directly assayed late-step anchor.
reference_section_type: LITERATURE_REVIEW
proposed_new_terms: []
suggested_questions:
- question: Does A0A314KWB2 function as a true beta-GD2-like nicotine glucoside hydrolase in Nicotiana attenuata, or is it a partially diverged homeolog?
- question: How much functional redundancy exists between the BGLU18_1 and BGLU18_6 copies in roots?
suggested_experiments:
- description: Compare BGLU18_1 and BGLU18_6 side by side in late-pathway glucoside hydrolysis assays.
experiment_type: comparative biochemical assay
hypothesis: BGLU18_1 is catalytically competent but weaker or differently tuned than the primary BGLU18_6 anchor.
- description: Generate single and double disruptions of the two BGLU18 candidates and quantify glucosylated late intermediates and nicotine accumulation.
experiment_type: genetics plus metabolite profiling
hypothesis: The two BGLU18 copies have overlapping but non-identical contributions to late nicotine-pathway flux.