| Claim/annotation item | Evidence type (direct for this gene vs inference from GH1 family vs related gene in other species) | Key details (reaction, motifs, localization, pathway) | Best supporting source (citation id) | Publication year | URL (if in evidence) |
|---|---|---|---|---|---|
| No direct literature found for Nicotiana attenuata BGLU18_6 / UniProt A0A1J6KFZ7 / ORF A4A49_57285 in retrieved papers | Direct search result for this exact gene: none | No retrieved paper directly mentioned the accession, gene symbol, or ORF; functional annotation must therefore rely on UniProt/domain assignment plus cautious family-level inference | (pqac-00000000) | 2018 | https://doi.org/10.1016/j.nbt.2017.08.012 |
| Protein is very likely a GH1 beta-glucosidase | Inference from GH1 family/domain assignment | GH1 beta-glucosidases hydrolyze β-glucosidic bonds between carbohydrate units or between a carbohydrate and an aglycone; this matches the UniProt description “Beta-glucosidase 18” and GH1/PF00232 domain assignment | (pqac-00000003) | 2020 | https://doi.org/10.3390/biom10050806 |
| Likely catalytic mechanism is retaining double-displacement hydrolysis using two catalytic glutamates | Inference from GH1 family | GH1 enzymes use a Koshland retaining mechanism with one glutamate as catalytic acid/base and one as nucleophile, proceeding through a glycosyl-enzyme intermediate | (pqac-00000001) | 2021 |  |
| Expected conserved catalytic motifs/residues include NEP/TXNEP and TENG/related motif containing the two catalytic glutamates | Inference from GH1 family | GH1 beta-glucosidases commonly contain conserved motifs harboring the catalytic glutamates; examples include NEP and TENG, or broader TXNEP/TFNEP-like motifs used to identify GH1 active sites | (pqac-00000002, pqac-00000001) | 2018; 2021 | https://doi.org/10.1016/j.ijbiomac.2018.04.156 |
| Expected structural fold is a canonical (α/β)8 TIM barrel | Inference from GH1 family | Structural studies of GH1 beta-glucosidases show the active site embedded in a TIM-barrel fold; catalytic glutamates occupy conserved positions in the barrel architecture | (pqac-00000000, pqac-00000005) | 2018 | https://doi.org/10.1016/j.nbt.2017.08.012 |
| Substrate specificity cannot be assigned specifically for BGLU18_6, but GH1 enzymes often range from aryl-β-glucosides to cellobiose and broader heterosides | Inference from GH1 family | GH1 beta-glucosidases are often classified as aryl-β-glucosidases, true cellobiases, or broad-specificity enzymes; therefore BGLU18_6 may act on small glucosides, but exact substrate must be experimentally determined | (pqac-00000002) | 2018 | https://doi.org/10.1016/j.ijbiomac.2018.04.156 |
| A plausible biological role is activation of defense or specialized metabolites by deglycosylation | Related gene/function in plants and microbes; cautious inference | Plant beta-glucosidases can activate chemical defense compounds and release active metabolites from conjugates; in a host-pathogen context, beta-glucosidase hydrolysis of scopolin releases scopoletin, illustrating how glucoside cleavage can alter defense chemistry | (pqac-00000003, pqac-00000004) | 2020; 2022 | https://doi.org/10.3390/biom10050806; https://doi.org/10.1128/mbio.00935-22 |
| Another plausible pathway context is phytohormone or stored-metabolite activation rather than primary cellulose digestion | Inference from plant GH1 functions | Plant beta-glucosidases are reported to release active phytohormones from conjugates and to activate defense chemistry; these roles are more consistent with many plant GH1 enzymes than bulk cellulose catabolism alone | (pqac-00000003) | 2020 | https://doi.org/10.3390/biom10050806 |
| Cellular localization remains unresolved for this exact gene | No direct evidence for this gene; limited family-level inference | Retrieved evidence did not identify subcellular localization for BGLU18_6; because plant GH1 beta-glucosidases can occur in multiple compartments, localization should be treated as unknown until sequence-based prediction or experiment confirms it | (pqac-00000003) | 2020 | https://doi.org/10.3390/biom10050806 |
| Active-site microenvironment can strongly influence substrate preference and hydrolysis vs transglycosylation | Inference from GH1 family structure-function studies | Comparative GH1 structures show that local pocket residues and water access alter glycone/aglycone binding and reaction outcome, implying that sequence-level family membership alone is insufficient to assign precise substrate specificity to BGLU18_6 | (pqac-00000000, pqac-00000006, pqac-00000007) | 2018 | https://doi.org/10.1016/j.nbt.2017.08.012 |


*Table: This table summarizes the available evidence and cautious inferences for functional annotation of Nicotiana attenuata BGLU18_6 (A0A1J6KFZ7). It highlights the absence of direct literature for the exact gene and shows which annotation items are supported only by GH1 family knowledge or related beta-glucosidase studies.*