A0A8B8L1Z3

UniProt ID: A0A8B8L1Z3
Organism: Abrus precatorius
Review Status: DRAFT
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Gene Description

A0A8B8L1Z3 (LOC113860185) is a 474-amino-acid protein from Abrus precatorius (Indian licorice). It has an N-terminal J domain (residues 70-135) followed by long low-complexity and disordered regions. It belongs to the plant-specific PTHR45496 family, subfamily SF19. The only Arabidopsis thaliana member of SF19 is At5g64360, which is known as SDJ1, DNAJ1 or EIP9. The Abrus protein is most similar to SDJ1 among Arabidopsis proteins (about 46% identity over its length) and the two have similar lengths. The J domain lacks the His-Pro-Asp (HPD) motif needed to stimulate Hsp70 ATPase activity. SDJ1 also lacks this motif, which argues against a canonical Hsp70 cochaperone role. In Arabidopsis, SDJ1 and its paralogs SDJ2 and SDJ3 are nuclear proteins. They lack DNA-binding domains. The SU(VAR)3-9 homologs SUVH1 and SUVH3, which read DNA methylation, recruit them to methylated euchromatic sites near transposons. There they enhance transcription of nearby genes, counteracting the silencing effect of transposon methylation. By descent, A0A8B8L1Z3 is predicted to be a nuclear transcriptional coactivator of this SUVH-SDJ type. The Abrus protein itself has not been characterized experimentally.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005634 nucleus
ISS
file:ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-bioinformatics/RESULTS-rereview.md 		NEW
Summary: Proposed nuclear location, inherited from PAINT node PTN002896004 and supported by experimental nuclear localization of the closest Arabidopsis relative EIP9/SDJ1.
Reason: GOA has no annotations for A0A8B8L1Z3. Abrus is not one of the PANTHER reference genomes, so it cannot receive IBA rows. PAINT placed nucleus (IBD) at PTN002896004, a flowering-plant node whose descendants include SDJ1 (SF19), SDJ2 (SF1), SDJ3 (SF10) and ADMETOS (SF32). A0A8B8L1Z3 is a flowering-plant SF19 member, so it descends from this node. EIP9/SDJ1 (At5g64360) has a direct nuclear localization result, and the SUVH-SDJ complex works on chromatin.
Supporting Evidence:
file:ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-bioinformatics/RESULTS-rereview.md
PAINT asserts nucleus (GO:0005634) and GO:0001228 "DNA-binding transcription activator
PMID:21700722
EMF1-EIP1, EMF1-EIP6 and EMF1-EIP9 heterodimers were localized in the nucleus
GO:0003713 transcription coactivator activity
ISS
file:ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-bioinformatics/RESULTS-rereview.md 		NEW
Summary: Proposed transcription coactivator activity, by descent from the SUVH-SDJ J-domain proteins. These proteins activate transcription when methyl-DNA readers recruit them to DNA.
Reason: At PTN002896004, PAINT asserts that SDJ-family proteins activate transcription, using GO:0001228 (DNA-binding transcription activator activity, RNA polymerase II-specific). This review keeps that function but uses the coactivator term instead of the DNA-binding transcription factor term, because the evidence points to a recruited coregulator. SDJ1 and SDJ2 have no DNA-binding domain. SUVH1 and SUVH3, which bind methylated DNA, recruit them to DNA, and activation was shown by tethering DNAJ1 artificially to DNA. SDJ2 already carries a direct experimental GO:0003713 annotation (PMID:30589221). This is a refinement of the term that PAINT assigned, not a function that PAINT left out. A0A8B8L1Z3 shares the subfamily of SDJ1/DNAJ1, the protein whose recruitment-dependent activation Harris et al. demonstrated. Confidence is moderate: no Abrus experiment exists.
Supporting Evidence:
PMID:30523112
Ectopic recruitment of DNAJ1 enhanced gene transcription in plants, yeast, and mammals.
PMID:30523112
DNAJ1 and DNAJ2 lack any discernible methyl-binding domain, but they are robustly associated with SUVH1 and SUVH3
PMID:30589221
We demonstrate that the SUVH-SDJ complex components have transcriptional activation activity.
file:ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-bioinformatics/RESULTS-rereview.md
The only Arabidopsis thaliana member of PTHR45496:SF19 is Q9FMF3 (At5g64360)

Core Functions

Predicted nuclear transcriptional coactivator of the SUVH-SDJ type. In Arabidopsis, the closest relative SDJ1/DNAJ1 (same PANTHER subfamily, SF19) has no DNA-binding domain. The methyl-DNA readers SUVH1 and SUVH3 recruit it to methylated euchromatin and transposon-proximal sites, where it enhances transcription of nearby genes. The J domain of A0A8B8L1Z3 lacks the HPD motif, so it may not act as a canonical Hsp70 cochaperone. How these proteins activate transcription is unknown. The earlier core function ("protein folding chaperone" in the cytoplasm) was based only on the generic J-domain signature and is withdrawn.

Molecular Function:
transcription coactivator activity
Directly Involved In:
positive regulation of DNA-templated transcription
Cellular Locations:
nucleus
Supporting Evidence:
  • PMID:30523112
    Thus, the SUVH proteins bind to methylated DNA and recruit the DNAJ proteins to enhance proximal gene expression, thereby counteracting the repressive effects of transposon insertion near genes.
  • file:ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-bioinformatics/RESULTS-rereview.md
    The query's J domain (residues 70-135) has no His-Pro-Asp tripeptide.

References

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Suggested Questions for Experts

Q: The PAINT node PTN002896004 is annotated with GO:0001228 (DNA-binding transcription activator activity, RNA polymerase II-specific). SDJ proteins have no DNA-binding domain and are recruited by SUVH1 and SUVH3. Should the node term be transcription coactivator activity (GO:0003713) instead?

Q: The J domain of SDJ1-type proteins has no HPD motif. Does it still bind any Hsp70? Or has it been repurposed to recruit transcriptional machinery?

Q: Does the Abrus SF19 protein interact with Abrus SUVH1/SUVH3 orthologs, and does it localize to methylated promoters?

Suggested Experiments

Experiment: Fuse A0A8B8L1Z3 to the GAL4 DNA-binding domain or a programmable zinc finger, and measure reporter activation in yeast and in Nicotiana benthamiana leaves. Include J-domain deletions as controls.

Hypothesis: A0A8B8L1Z3 activates transcription when it is recruited to DNA.

Type: reporter assay

Experiment: Co-express GFP-tagged A0A8B8L1Z3 with tagged Abrus SUVH1/SUVH3 orthologs in N. benthamiana. Image the proteins by confocal microscopy with a nuclear marker, then perform co-immunoprecipitation.

Hypothesis: A0A8B8L1Z3 is nuclear and forms a complex with Abrus SUVH1/SUVH3 orthologs.

Type: fluorescence microscopy and co-immunoprecipitation

External Prediction Reviews

These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.

ProtNLM2 External predictions

View prediction review YAML · A0A8B8L1Z3-protnlm-predictions-review.yaml · Review status: COMPLETE

A0A8B8L1Z3 is an uncharacterized Abrus precatorius J-domain protein in the plant-specific PTHR45496:SF19 subfamily, whose only Arabidopsis member is SDJ1/DNAJ1/EIP9 (At5g64360). The gene review predicts a nuclear SUVH-SDJ-type transcriptional coactivator by descent from PAINT node PTN002896004, which asserts nucleus. The single ProtNLM2 prediction, endoplasmic reticulum, places the protein in a compartment that this evidence contradicts and that no sequence feature supports.

Source documents: genes/ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-uniprot.txt · genes/ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-goa.tsv · genes/ABRPR/A0A8B8L1Z3/A0A8B8L1Z3-ai-review.yaml

Review score: 2 = concordant with evidence; 1 = uncertain; 0 = discordant with evidence. This is an assessment score, not a model probability.

GO:0005783 endoplasmic reticulum GO_CC
NPI — Nonparalog incorrect Review score: 0/2
Prediction method: ProtNLM2 · Version: UniProt 2024_06 pilot
Review rationale: GOA has no annotations for this protein, so an ER term would be novel, but the available evidence points to the nucleus instead. A0A8B8L1Z3 is in PTHR45496:SF19 and is closest among Arabidopsis proteins to SDJ1/DNAJ1/EIP9 (about 46% identity over a similar length). PAINT asserts nucleus at node PTN002896004, which spans the SDJ1, SDJ2, SDJ3 and ADMETOS subfamilies. EIP9/SDJ1 heterodimers with EMF1 localize to the nucleus, and SDJ1/DNAJ1 is recruited to methylated DNA by the SUVH1/SUVH3 methyl readers, where it enhances transcription. The UniProt record shows no signal peptide or transmembrane segment, only an N-terminal J domain followed by disordered regions. The J domain lacks the HPD motif, which argues against the protein acting as an Hsp70 (for example BiP) cochaperone at the ER. The ER label most likely reflects the many ER-resident J-domain proteins rather than any feature of this subfamily. No literature reports ER localization for any SF19 member.
Supporting Evidence:

Deep Research

Falcon

(A0A8B8L1Z3-deep-research-falcon.md)

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📚 Additional Documentation

Notes

(A0A8B8L1Z3-notes.md)

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📄 View Raw YAML

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