id: P16579 gene_symbol: WIN6 product_type: PROTEIN status: DRAFT taxon: id: NCBITaxon:3694 label: Populus trichocarpa description: Wound-inducible secreted acidic endochitinase of glycoside hydrolase family 19 (class I chitinase). It comprises an N-terminal chitin-binding type-1 (hevein-like) domain joined by a spacer to a C-terminal catalytic chitinase domain, and randomly hydrolyzes the beta-1,4 linkages of chitin and chitodextrins. The enzyme contributes to plant defense against chitin-containing fungal pathogens, and its expression is activated systemically by wounding. alternative_records: - id: B9HQY4 relationship: REFERENCE_PROTEOME_CANDIDATE reference_proteome: UP000006729 reviewed_on: '2026-10-19' reason: Retain P16579 as the primary Swiss-Prot accession. B9HQY4 at POPTR_009G141800v4 is the leading candidate, not an established equivalent. It has 317 identical residues across 340 global-alignment columns (16 substitutions and seven gap columns). B9HQZ1 represents a second model of the same locus, while nearby chitinase loci also match strongly. Hybrid H11-11 provenance and the absence of a direct locus cross-reference leave allele, model, and paralog alternatives unresolved. Mapping source genomic record U01661, including flanks, to the reference assembly is needed before promoting this relationship. evidence: - type: SEQUENCE_COMPARISON description: MMseqs2 searched all 77,340 sequences in UP000006729 (release 2026_03); global BLOSUM62 alignments were computed for every returned hit. B9HQY4 ranks first by global alignment score, with 93.2353% identity including gap columns, 97.9412% query coverage and 100.0% target coverage. The saved candidate table and alignments retain competing matches and residue-level differences. The search is heuristic, and sequence similarity alone is not definitive genomic mapping. Identity over paired residues is 95.1952% (317/333); gap columns are excluded from this denominator. supported_by: - reference_id: file:POPTR/WIN6/WIN6-record-evidence.yaml supporting_text: |- query_length: 340 target_length: 333 alignment_columns: 340 identities: 317 mismatches: 16 gap_columns: 7 identity_percent: 93.2353 query_coverage_percent: 97.9412 target_coverage_percent: 100.0 - type: PROTEOME_MEMBERSHIP description: Current UniProtKB and proteome records place B9HQY4, but not P16579, in reference proteome UP000006729. Both UniProt records use NCBITaxon:3694; source-organism qualifications are recorded separately. supported_by: - reference_id: file:POPTR/WIN6/WIN6-record-evidence.yaml supporting_text: |- reference_proteome: UP000006729 proteome_is_reference: true proteome_taxon_matches: true primary_in_reference_proteome: false alternative_in_reference_proteome: true - type: RECORD_HISTORY description: UniSave versions 109 (2015), 128 (2020), and 138 (2024) lack Proteomes cross-references. These dated samples support longstanding absence at those dates; they do not establish uninterrupted absence, a removal event, or UniProt's motivation. supported_by: - reference_id: file:POPTR/WIN6/WIN6-record-evidence.yaml supporting_text: |- sampled_history_versions: - 109 - 128 - 138 sampled_versions_with_proteome_links: [] - type: CURATION_CONTEXT description: ENA assigns the original genomic sequence U01661 to Populus trichocarpa x Populus deltoides, strain H11-11, whereas UniProtKB assigns P16579 to taxon 3694. This hybrid origin is relevant even though the live UniProt taxonomy matches the reference species. supported_by: - reference_id: file:POPTR/WIN6/WIN6-record-evidence.yaml supporting_text: /organism="Populus trichocarpa x Populus deltoides" - reference_id: file:POPTR/WIN6/WIN6-record-evidence.yaml supporting_text: /strain="H11-11" existing_annotations: - term: id: GO:0004568 label: chitinase activity evidence_type: IEA original_reference_id: GO_REF:0000002 qualifier: enables review: summary: General chitinase activity is correct but a more precise endochitinase term is available and better matches the catalytic activity. action: MODIFY reason: The catalytic activity is random endo-hydrolysis of chitin, which is captured precisely by endochitinase activity rather than the broader chitinase parent. supported_by: - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["CC:CATALYTIC ACTIVITY"] supporting_text: Reaction=Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide proposed_replacement_terms: - id: GO:0008843 label: endochitinase activity - term: id: GO:0005975 label: carbohydrate metabolic process evidence_type: IEA original_reference_id: GO_REF:0000002 qualifier: involved_in review: summary: Carbohydrate metabolic process is correct but is a high-level parent term that is less informative than the chitin catabolic process for this specific chitin-degrading enzyme. action: KEEP_AS_NON_CORE reason: The more specific chitin catabolic process and cell wall macromolecule catabolic process terms already capture the biological role; the generic carbohydrate metabolism parent is true but redundant, so it is retained as a non-core annotation. supported_by: - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["CC:CATALYTIC ACTIVITY"] supporting_text: Reaction=Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide - term: id: GO:0006032 label: chitin catabolic process evidence_type: IEA original_reference_id: GO_REF:0000002 qualifier: involved_in review: summary: Chitin catabolic process is the direct biological process for this endochitinase. action: ACCEPT reason: The enzyme hydrolyzes chitin, so chitin catabolism is the immediate process it participates in. supported_by: - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["CC:CATALYTIC ACTIVITY"] supporting_text: Reaction=Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide - reference_id: file:POPTR/WIN6/WIN6-deep-research-openai.md supporting_text: Random endo-hydrolysis of β-1,4 linkages in chitin/chitodextrins (endochitinase activity). - term: id: GO:0008061 label: chitin binding evidence_type: IEA original_reference_id: GO_REF:0000120 qualifier: enables review: summary: Chitin binding is supported by the N-terminal chitin-binding type-1 domain but is a substrate-binding activity supporting catalysis rather than the core molecular function. action: KEEP_AS_NON_CORE reason: The protein has a dedicated chitin-binding type-1 domain, so chitin binding is well supported, but it is auxiliary to the catalytic endochitinase activity. supported_by: - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["DR:GO"] supporting_text: DR GO; GO:0008061; F:chitin binding; IEA:UniProtKB-KW. - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["FT:DOMAIN"] supporting_text: /note="Chitin-binding type-1" - term: id: GO:0008843 label: endochitinase activity evidence_type: IEA original_reference_id: GO_REF:0000003 qualifier: enables review: summary: Endochitinase activity is the precise core molecular function, matching the catalytic activity and EC 3.2.1.14. action: ACCEPT reason: UniProt records random endo-hydrolysis of chitin under EC 3.2.1.14, which is exactly endochitinase activity. supported_by: - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["CC:CATALYTIC ACTIVITY"] supporting_text: Reaction=Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide - reference_id: file:POPTR/WIN6/WIN6-deep-research-openai.md supporting_text: Strongly support `GO:0008843` (endochitinase activity). - term: id: GO:0016998 label: cell wall macromolecule catabolic process evidence_type: IEA original_reference_id: GO_REF:0000002 qualifier: involved_in review: summary: Cell wall macromolecule catabolic process fits degradation of fungal cell wall chitin during defense. action: ACCEPT reason: Hydrolysis of chitin, a fungal cell wall polysaccharide, is a cell wall macromolecule catabolic process consistent with the antifungal role. supported_by: - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["CC:FUNCTION"] supporting_text: 'FUNCTION: Defense against chitin-containing fungal pathogens.' - term: id: GO:0050832 label: defense response to fungus evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: involved_in review: summary: Defense response to fungus is supported by the documented antifungal function and wound induction. action: ACCEPT reason: UniProt states the protein functions in defense against chitin-containing fungal pathogens and is wound-inducible, consistent with an antifungal defense role. supported_by: - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["CC:FUNCTION"] supporting_text: 'FUNCTION: Defense against chitin-containing fungal pathogens.' - reference_id: file:POPTR/WIN6/WIN6-deep-research-openai.md supporting_text: Defense against chitin-containing fungal pathogens. references: - id: file:POPTR/WIN6/WIN6-record-evidence.yaml title: Compact archived record and sequence evidence for P16579 - id: GO_REF:0000002 title: Gene Ontology annotation through association of InterPro records with GO terms findings: - statement: GO_REF:0000002 supplied one or more source GOA annotations reviewed in this file. - id: GO_REF:0000003 title: Gene Ontology annotation based on Enzyme Commission mapping findings: - statement: GO_REF:0000003 supplied the EC-based endochitinase activity annotation reviewed in this file. - id: GO_REF:0000117 title: Electronic Gene Ontology annotations created by ARBA machine learning models findings: - statement: GO_REF:0000117 supplied the defense response to fungus annotation reviewed in this file. - id: GO_REF:0000120 title: Combined Automated Annotation using Multiple IEA Methods findings: - statement: GO_REF:0000120 supplied the chitin binding annotation reviewed in this file. - id: file:POPTR/WIN6/WIN6-uniprot.txt title: UniProtKB reviewed entry for WIN6 findings: - statement: UniProt describes WIN6 as a wound-inducible GH19 class I acidic endochitinase with a chitin-binding type-1 domain that defends against chitin-containing fungal pathogens. - id: file:POPTR/WIN6/WIN6-deep-research-openai.md title: Deep research synthesis for WIN6 findings: - statement: Deep research supports endochitinase activity as the core function and a wound-induced antifungal defense role for WIN6. - id: file:POPTR/WIN6/WIN6-goa.tsv title: QuickGO GOA annotations for WIN6 findings: - statement: GOA rows supplied the existing_annotations reviewed in this file. core_functions: - description: Randomly hydrolyzes the beta-1,4 linkages of chitin as a secreted endochitinase, degrading fungal cell wall chitin as part of wound-inducible defense against fungal pathogens. molecular_function: id: GO:0008843 label: endochitinase activity directly_involved_in: - id: GO:0006032 label: chitin catabolic process - id: GO:0016998 label: cell wall macromolecule catabolic process - id: GO:0050832 label: defense response to fungus locations: [] supported_by: - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["CC:CATALYTIC ACTIVITY"] supporting_text: Reaction=Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide - reference_id: file:POPTR/WIN6/WIN6-uniprot.txt record_section: ["CC:FUNCTION"] supporting_text: 'FUNCTION: Defense against chitin-containing fungal pathogens.' proposed_new_terms: [] suggested_questions: - question: Does WIN6 act primarily against fungal pathogens, or does it also contribute to anti-insect defense given its wound-inducible expression? suggested_experiments: - description: Assay recombinant WIN6 endochitinase activity against chitin substrates and test antifungal inhibition of hyphal growth in vitro. experiment_type: targeted enzymatic and antifungal assay