Q2U1U6

UniProt ID: Q2U1U6
Organism: Aspergillus oryzae (strain ATCC 42149 / RIB 40)
Review Status: DRAFT
Aliases:
AO090138000091
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Gene Description

Q2U1U6 (AO090138000091) is a small (134 aa) uncharacterized protein from Aspergillus oryzae RIB 40 that contains a Chondroitin_lyas domain (InterPro IPR008929) and matches the Chondroitin AC/alginate lyase superfamily fold (SUPFAM SSF48230). These domain signatures place the protein in the polysaccharide lyase superfamily, whose members cleave glycosidic bonds in acidic polysaccharides via a beta-elimination mechanism rather than hydrolysis. The predicted substrates, by analogy to characterized family members, are glycosaminoglycans such as chondroitin sulfate, dermatan sulfate, or hyaluronic acid. No experimental characterization of this specific protein has been published. The protein is encoded on chromosome 6 of the A. oryzae RIB 40 genome. Aspergillus section Flavi species encode extensive carbohydrate-active enzyme (CAZyme) repertoires, and the presence of a putative glycosaminoglycan lyase is consistent with the broad polysaccharide-degrading capacity of this lineage.

Core Functions

Predicted polysaccharide lyase activity based on the Chondroitin_lyas domain (IPR008929) and Chondroitin AC/alginate lyase superfamily fold (SSF48230). The protein likely cleaves glycosidic bonds in acidic polysaccharides (glycosaminoglycans) via beta-elimination. The exact substrate specificity (chondroitin sulfate, dermatan sulfate, hyaluronan, or alginate) cannot be determined without experimental characterization.

Molecular Function:
carbon-oxygen lyase activity, acting on polysaccharides
Directly Involved In:
polysaccharide catabolic process
Cellular Locations:
extracellular region
Supporting Evidence:
  • UniProt:Q2U1U6
    InterPro; IPR008929; Chondroitin_lyas.
  • UniProt:Q2U1U6
    SUPFAM; SSF48230; Chondroitin AC/alginate lyase; 1.
  • file:ASPOR/Q2U1U6/Q2U1U6-deep-research-falcon.md
    Q2U1U6 is predicted to function as a polysaccharide lyase capable of degrading glycosaminoglycans through a beta-elimination mechanism

References

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Suggested Questions for Experts

Q: Does Q2U1U6 have a signal peptide or other secretion signal? At 134 amino acids it is unusually small for a secreted polysaccharide lyase; is it a functional enzyme or a gene prediction artifact?

Q: What is the substrate specificity of Q2U1U6? The Chondroitin_lyas domain is found in enzymes acting on chondroitin sulfate, dermatan sulfate, hyaluronic acid, and alginate.

Q: Is there a complete glycosaminoglycan utilization pathway in A. oryzae (downstream GH88 unsaturated glucuronyl hydrolase, sulfatases, transporters), or is this an isolated enzyme?

Suggested Experiments

Experiment: Recombinant expression and enzymatic assay with defined GAG substrates (chondroitin sulfate A/C, dermatan sulfate, hyaluronic acid, alginate) monitoring delta-4,5-unsaturated product formation at 232 nm to determine substrate specificity and kinetic parameters.

Hypothesis: Q2U1U6 has polysaccharide lyase activity toward one or more glycosaminoglycan substrates.

Type: biochemical assay

Experiment: AlphaFold structure analysis (entry available in AlphaFoldDB) to identify active site residues and compare to characterized chondroitin lyases for clues to substrate preference and cleavage mode.

Hypothesis: Structural comparison will reveal conserved active site architecture diagnostic of a specific polysaccharide lyase subfamily.

Type: computational structural analysis

Experiment: RT-qPCR or RNA-seq under growth on different carbon sources (GAGs, plant polysaccharides, simple sugars) to determine expression conditions and infer physiological substrate.

Hypothesis: Q2U1U6 expression is induced by glycosaminoglycan substrates, indicating a physiological role in GAG catabolism.

Type: transcriptomics

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 · Q2U1U6-protnlm-predictions-review.yaml · Review status: COMPLETE

The 134-residue protein has a partial polysaccharide-lyase-like fold assignment. Neither polysaccharide catabolism nor O-glycosyl hydrolase activity is established for this short sequence.

Source documents: genes/ASPOR/Q2U1U6/Q2U1U6-uniprot.txt · genes/ASPOR/Q2U1U6/Q2U1U6-goa.tsv · genes/ASPOR/Q2U1U6/Q2U1U6-hypotheses/prediction-glycoside-hydrolase/openscientist.md

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

GO:0000272 polysaccharide catabolic process GO_BP
UNC — Uncertain Review score: 1/2
Prediction method: ProtNLM2 · Version: UniProt 2024_06 pilot
Review rationale: The sole InterPro assignment is the chondroitin-lyase-like structural superfamily IPR008929 in a 134-residue sequence. A partial fold assignment does not establish a complete catalytic enzyme or its physiological substrate. Polysaccharide catabolism is plausible for some proteins with this fold, but the inspected sources contain neither a diagnostic complete enzyme architecture nor a target assay. The term is absent from the cached annotations and remains uncertain.
Supporting Evidence:
GO:0004553 hydrolase activity, hydrolyzing O-glycosyl compounds GO_MF
NPI — Nonparalog incorrect Review score: 0/2
Prediction method: ProtNLM2 · Version: UniProt 2024_06 pilot
DOMAIN ARCHITECTURE MISMATCH
Review rationale: IPR008929 identifies a partial chondroitin/alginate-lyase-like fold in a 134-residue protein, not an experimentally demonstrated O-glycosyl hydrolase. The focused report found that the only mechanistic lead is a lyase superfamily assignment, not a glycoside hydrolase family, and that the match is too short to establish even a complete lyase enzyme. The GO:0004553 molecular-function prediction is therefore an off-class transfer from a fragmentary lyase-like fold to a hydrolytic activity; the inspected evidence supports leaving molecular function uncharacterized rather than adding a lyase replacement.
Supporting Evidence:

Deep Research

Falcon

(Q2U1U6-deep-research-falcon.md)

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OpenScientist

(Q2U1U6-hypotheses/prediction-glycoside-hydrolase/openscientist.md)

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