LYZ is the single chicken-type (c-type) lysozyme of the common vampire bat, a secreted glycoside hydrolase of family GH22 (EC 3.2.1.17). The 148-residue precursor has a signal peptide (residues 1-18) and a cleaved 19-148 mature chain that adopts the canonical lysozyme C fold. It hydrolyses the beta-(1->4) linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine in bacterial peptidoglycan, and between N-acetylglucosamine residues in chitodextrins, degrading the cell wall and lysing the bacterium. Its physiological setting is extracellular: it is a classical innate immune effector of body fluids and secretions, and in D. rotundus it is one of the antimicrobials that dominate the accessory submaxillary salivary gland, where it was detected at both transcript and protein level, and it is also transcribed in liver. Unlike insectivorous bats, which duplicated and neofunctionalised lysozyme for chitin digestion, vampire bats retain a single lysozyme gene; that gene carries a signature of positive selection on the mature protein specific to the sanguivorous lineage, with substitutions predicted to alter function, consistent with adaptation of antimicrobial defence to a blood diet.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0003796
lysozyme activity
|
IEA
GO_REF:0000120 |
ACCEPT |
Summary: UniProt records the EC 3.2.1.17 reaction for this protein, it is assigned to glycosyl hydrolase family 22, and PANTHER places it in subfamily PTHR11407:SF28 LYSOZYME C. Muramidase activity is the core molecular function.
Reason: Catalytic activity statement, GH22 family assignment, and lysozyme C subfamily assignment all agree. This is the defining activity of the protein.
Supporting Evidence:
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
Hydrolysis of (1->4)-beta-linkages between N-acetylmuramic
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
Belongs to the glycosyl hydrolase 22 family.
|
|
GO:0003824
catalytic activity
|
IEA
GO_REF:0000043 |
MODIFY |
Summary: Root-level catalytic activity derived from the Hydrolase keyword. The specific reaction is known and already annotated.
Reason: Replace with the specific GO:0003796 lysozyme activity.
Proposed replacements:
lysozyme activity
Supporting Evidence:
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
Hydrolysis of (1->4)-beta-linkages between N-acetylmuramic
|
|
GO:0016787
hydrolase activity
|
IEA
GO_REF:0000043 |
MODIFY |
Summary: Keyword-derived parent term. The exact hydrolytic reaction is specified in the UniProt catalytic activity block.
Reason: Replace with the specific GO:0003796 lysozyme activity.
Proposed replacements:
lysozyme activity
Supporting Evidence:
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
Hydrolysis of (1->4)-beta-linkages between N-acetylmuramic
|
|
GO:0016798
hydrolase activity, acting on glycosyl bonds
|
IEA
GO_REF:0000043 |
MODIFY |
Summary: Keyword-derived intermediate parent. Correct but two levels more general than the annotated EC 3.2.1.17 reaction.
Reason: Replace with the specific GO:0003796 lysozyme activity.
Proposed replacements:
lysozyme activity
Supporting Evidence:
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
Hydrolysis of (1->4)-beta-linkages between N-acetylmuramic
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
Belongs to the glycosyl hydrolase 22 family.
|
|
GO:0050830
defense response to Gram-positive bacterium
|
IEA
GO_REF:0000118 |
ACCEPT |
Summary: Gram-positive bacteria are the canonical target of c-type lysozymes, because their thick peptidoglycan is directly accessible to the enzyme. The human orthologue LYZ carries this annotation from direct assay (IDA), and the TreeGrafter propagation to the bat protein is appropriate. An earlier version of this review proposed replacing this term with the broader GO:0042742; that would discard information, since the general term is separately annotated and retained.
Reason: This is the well-supported, mechanistically explained specificity of c-type lysozyme, and the broad parent is annotated separately. Keep the specific term.
Supporting Evidence:
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
Lysozymes have primarily a bacteriolytic function
file:DESRO/K9IWH5/K9IWH5-deep-research-falcon.md
GH22 lysozymes prefer Gram-positive bacteria due to accessibility of peptidoglycan, but they can exhibit activity against Gram-negative bacteria when the outer membrane barrier is compromised
|
|
GO:0050829
defense response to Gram-negative bacterium
|
IEA
GO_REF:0000118 |
ACCEPT |
Summary: Activity against Gram-negative bacteria is the secondary, well-described behaviour of mammalian c-type lysozymes: the outer membrane shields the peptidoglycan, so killing requires permeabilisation, but the activity is real and the human orthologue carries the same annotation by phylogenetic inference. As with the Gram-positive term, an earlier version of this review proposed generalising this to GO:0042742, which would lose the distinction between the primary and secondary spectrum.
Reason: Consistent with the characterised spectrum of mammalian c-type lysozyme and with the same TreeGrafter propagation applied to the human orthologue. Retained at the specific level.
Supporting Evidence:
file:DESRO/K9IWH5/K9IWH5-deep-research-falcon.md
GH22 lysozymes prefer Gram-positive bacteria due to accessibility of peptidoglycan, but they can exhibit activity against Gram-negative bacteria when the outer membrane barrier is compromised
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
Lysozymes have primarily a bacteriolytic function
|
|
GO:0042742
defense response to bacterium
|
IEA
GO_REF:0000043 |
ACCEPT |
Summary: The general antibacterial defence term, correct as the umbrella over the two spectrum-specific terms above. Supported by the UniProt Antimicrobial and Bacteriolytic enzyme keywords and by the description of c-type lysozyme as an innate immune effector that kills bacteria by degrading their cell wall peptidoglycan.
Reason: Correct and directly supported. Retained as the general parent alongside the specific Gram-positive and Gram-negative terms.
Supporting Evidence:
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
Lysozymes have primarily a bacteriolytic function
PMID:31506780
killing bacteria by degrading peptidoglycan in their cell walls
|
|
GO:0031640
killing of cells of another organism
|
IEA
GO_REF:0000043 |
ACCEPT |
Summary: This is precisely what a muramidase does: hydrolysing peptidoglycan weakens the cell wall and lyses the bacterium. The human orthologue LYZ carries this term from direct assay (IDA, PMID:9727055). An earlier version of this review marked it as over-annotated on the grounds that it is broad, but breadth is not the issue here - the term states the outcome of the enzyme's own catalytic action.
Reason: Bacteriolysis is the direct, demonstrated consequence of lysozyme activity, not an inflated inference. The keyword source (Bacteriolytic enzyme) is exactly on point.
Supporting Evidence:
PMID:31506780
killing bacteria by degrading peptidoglycan in their cell walls
file:DESRO/K9IWH5/K9IWH5-deep-research-falcon.md
thereby weakening the cell wall and causing osmotic lysis
|
|
GO:0005576
extracellular region
|
ISS
file:DESRO/K9IWH5/K9IWH5-uniprot.txt |
NEW |
Summary: Proposed new annotation. The GOA record for K9IWH5 carries no cellular component term at all, which is a genuine gap: the precursor has a SignalP-predicted signal peptide (1-18) with a cleaved 19-148 mature chain, lysozyme is a classical secreted protein of body fluids, the human orthologue is annotated to GO:0005576 from direct assay, and lysozyme was recovered from the D. rotundus accessory submaxillary gland by both transcriptome and proteome analysis.
Reason: Fills a missing aspect. The ISS evidence code rests on the sequence and orthology basis recorded in the UniProt entry - the cleaved signal peptide and the secreted human orthologue - which is why the reference is the UniProt record rather than a publication. The Vampirome study is retained as corroborating support, but its proteome was taken from dissected gland tissue rather than secreted saliva, so it is not by itself direct evidence of extracellular localisation.
Supporting Evidence:
file:DESRO/K9IWH5/K9IWH5-uniprot.txt
SIGNAL 1..18
PMID:23411029
families were expressed at higher levels in the AC gland, as indicated by both transcriptome and proteome analysis (Figure 2B).
file:DESRO/K9IWH5/K9IWH5-deep-research-falcon.md
These features support extracellular localization (secreted protein) as primary functional context.
|
Q: Do the positively selected substitutions in vampire bat mature lysozyme change its catalytic properties or antibacterial spectrum relative to lysozymes of insectivorous and frugivorous phyllostomid bats?
Suggested experts: David M. Irwin, Yang Liu
Q: Is salivary lysozyme delivered to the host bite wound in amounts that matter for wound microbiology, or does it act principally to protect the bat's own oral cavity and ingested blood meal?
Suggested experts: Ivo M. B. Francischetti, José M. C. Ribeiro
Q: Why is lysozyme concentrated in the accessory rather than the principal submaxillary gland, and does that compartmentalisation separate antimicrobial from anti-hemostatic salivary functions?
Experiment: Express recombinant D. rotundus LYZ alongside lysozyme from a frugivorous phyllostomid and human LYZ; compare turbidimetric muramidase rates on Micrococcus lysodeikticus cell walls across pH and NaCl gradients, and determine minimum inhibitory concentrations against Gram-positive and Gram-negative bacteria with and without an outer-membrane permeabiliser. Test individual sanguivore-clade substitutions by site-directed mutagenesis in the frugivorous background.
Hypothesis: Sanguivore-specific substitutions in vampire bat lysozyme alter its antibacterial spectrum or its activity under the ionic conditions of blood.
Type: Recombinant enzymology with site-directed mutagenesis
Experiment: Quantify lysozyme in saliva expectorated by feeding bats by targeted parallel reaction monitoring mass spectrometry, and localise the protein within accessory versus principal submaxillary gland sections by immunohistochemistry.
Hypothesis: Vampire bat lysozyme is secreted into saliva and reaches the host bite site.
Type: Targeted proteomics and immunohistochemistry
Experiment: Measure lysozyme transcript abundance and muramidase activity in stomach and intestinal tissue and contents versus salivary gland, and assay the recombinant enzyme for stability and activity at gastric pH and against pepsin.
Hypothesis: In the absence of a duplicated paralogue, the single vampire bat lysozyme also acts on the ingested blood meal in the digestive tract.
Type: Tissue expression profiling with activity assay
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.
Plan status update
- Objective 1 (identity verification): LYZ corresponds to a c-type lysozyme (muramidase; EC 3.2.1.17) that hydrolyzes peptidoglycan and belongs to the classical GH22 lysozyme family. The UniProt-provided domains (Glyco_hydro_22) and function align with current literature on c-type lysozymes; no conflicting genes with the same symbol were identified in our retrieved evidence. Organism: Desmodus rotundus is correct; however, species-specific publications directly documenting this UniProt entry’s properties are limited in the retrieved 2023–2024 literature. We proceed with a careful functional annotation anchored to GH22 lysozyme evidence and clearly mark species-specific gaps (matwiejczyk2025lysozymemonomerdimer pages 2-3, matwiejczyk2025lysozymemonomerdimer pages 3-5).
Comprehensive research report: LYZ (UniProt K9IWH5) from Desmodus rotundus
1) Key concepts and definitions
- Molecular identity and reaction class: LYZ encodes a c-type lysozyme (muramidase) that cleaves the β(1→4) glycosidic bond in bacterial peptidoglycan, thereby weakening the cell wall and causing osmotic lysis. This activity is prototypical of GH22 lysozymes and is strongest against Gram-positive bacteria with thick peptidoglycan layers (matwiejczyk2025lysozymemonomerdimer pages 2-3, gillaniUnknownyearunveilingtheproduction pages 5-7, gillaniUnknownyearunveilingtheproduction pages 3-5).
- Substrate: The immediate chemical substrate is the N-acetylmuramic acid (NAM)–N-acetylglucosamine (NAG) polymer of peptidoglycan; lysozyme targets the β(1→4) linkage between NAM and NAG (gillaniUnknownyearunveilingtheproduction pages 5-7, gillaniUnknownyearunveilingtheproduction pages 3-5).
- Physiological role: Lysozyme is a canonical innate immune effector present in secretions and immune cells, contributing to direct bacteriolysis and to immunomodulation via peptidoglycan fragment generation and other non-enzymatic antimicrobial effects (e.g., membrane perturbation due to cationic character) (matwiejczyk2025lysozymemonomerdimer pages 2-3, gillaniUnknownyearunveilingtheproduction pages 5-7).
2) Mechanism and catalytic features
- Mechanistic class: c-type (GH22) lysozymes catalyze hydrolysis of the NAM–NAG β(1→4) bond through a classical active site containing multiple subsites for sugar binding. A conserved catalytic glutamate/aspartate dyad (classically Glu35 and Asp52 in hen egg-white lysozyme numbering) provides acid/base catalysis and nucleophile/general base functions, consistent with a retaining glycosidase mechanism described for GH22 lysozymes (matwiejczyk2025lysozymemonomerdimer pages 3-5).
- Structural determinants: GH22 lysozymes are small, highly basic proteins stabilized by multiple disulfide bonds that maintain the integrity of the catalytic cleft; at least two disulfides are required to preserve activity, and oxidation of key residues (e.g., Met, Trp, Tyr) can inactivate enzyme activity (matwiejczyk2025lysozymemonomerdimer pages 2-3, matwiejczyk2025lysozymemonomerdimer pages 7-9).
3) Substrate specificity and organismal context
- Peptidoglycan targeting: GH22 lysozymes prefer Gram-positive bacteria due to accessibility of peptidoglycan, but they can exhibit activity against Gram-negative bacteria when the outer membrane barrier is compromised or via engineered/modified forms that enhance permeabilization (e.g., conjugation with polymers, synergy with chelators or other antimicrobials) (matwiejczyk2025lysozymemonomerdimer pages 2-3, gillaniUnknownyearunveilingtheproduction pages 5-7, matwiejczyk2025lysozymemonomerdimer pages 9-10).
4) Protein family/domains and evolutionary context
- Family: LYZ belongs to the c-type lysozyme family within GH22; c-, g-, and i-type lysozymes constitute the major lysozyme classes. GH22 lysozymes share a conserved core fold and catalytic architecture. The literature consistently describes c-type lysozymes (including human and chicken) as GH22, with broadly conserved catalytic features across vertebrates (matwiejczyk2025lysozymemonomerdimer pages 2-3, matwiejczyk2025lysozymemonomerdimer pages 3-5).
- Lysozyme–lactalbumin relationship: While this report centers on GH22 lysozymes, many sources note evolutionary and structural relationships between c-type lysozymes and mammalian α-lactalbumins; both are small secreted proteins with related folds, though only lysozymes are glycoside hydrolases (context consistent with GH22 literature; see general GH22 lysozyme overviews) (matwiejczyk2025lysozymemonomerdimer pages 2-3).
5) Cellular localization and secretion (mammals)
- Secretions and immune compartments: Lysozyme is widely distributed in body fluids (e.g., saliva, tears, milk) and present in immune cells; it contributes to mucosal/secreted antimicrobial defense and innate immunity in blood/tissues (matwiejczyk2025lysozymemonomerdimer pages 2-3). These features support extracellular localization (secreted protein) as primary functional context. Specific cell-type attributions (e.g., neutrophil granules, Paneth cells) are well established in the broader literature, but were not retrieved as citable items in our extracted evidence set; therefore, we conservatively report secretion and immune localization based on available sources (matwiejczyk2025lysozymemonomerdimer pages 2-3).
6) Evidence for Desmodus rotundus/bats; species-specific considerations
- Data limitations and inference: Our focused searches retrieved limited, directly citable 2023–2024 sources documenting LYZ protein expression in vampire bat saliva or serum in the evidence set. Older studies and broader bat literature exist but were not captured as evidence here; accordingly, we do not assert species-specific claims beyond UniProt identity and GH22 inference. Function is inferred from conserved GH22/c-type lysozyme properties: secreted muramidase active on peptidoglycan, contributing to innate defense at mucosal surfaces (matwiejczyk2025lysozymemonomerdimer pages 2-3, matwiejczyk2025lysozymemonomerdimer pages 3-5).
- Statement of ambiguity: The gene symbol LYZ is not ambiguous in this context, and the UniProt record (K9IWH5) specifies a GH22 lysozyme in Desmodus rotundus. However, species-specific experimental literature within 2023–2024 supporting saliva or serum detection and adaptive evolution was not recovered by our evidence tool; thus, we annotate function primarily by family/domain inference (matwiejczyk2025lysozymemonomerdimer pages 2-3, matwiejczyk2025lysozymemonomerdimer pages 3-5).
7) Recent developments and latest research (emphasis 2023–2024)
- Antibiofilm and surface applications: Reviews and applied reports highlight lysozyme’s integration into wound dressings, implant coatings, and polymeric films, where immobilized lysozyme can prevent Staphylococcus aureus biofilms for extended periods (e.g., >14 days) and inhibit biofilms with microgram loadings embedded in membranes, illustrating real-world anti-biofilm use cases (matwiejczyk2025lysozymemonomerdimer pages 9-10, matwiejczyk2025lysozymemonomerdimer pages 7-9).
- Enzyme engineering and delivery: Chemical conjugation (e.g., dextran, PEGylation, fatty acylation) and formulation advances enhance Gram-negative activity, stability, and half-life; recombinant production in E. coli or yeast with engineered tags/inteins and CRISPR-assisted optimization is commonly used for yield and secretion improvements (gillaniUnknownyearunveilingtheproduction pages 3-5, gillaniUnknownyearunveilingtheproduction pages 9-9).
- Diagnostics and analytical tools: Lysozyme activity underpins workflows that digest peptidoglycan into NAM/NAG disaccharides for downstream analytical labeling and detection; recent chemical biology demonstrates peptidoglycan labeling strategies that rely on lysozyme digestion steps to analyze NAG/NAM-containing fragments, underscoring lysozyme’s utility in modern glycobiology workflows (gillaniUnknownyearunveilingtheproduction pages 9-9). Activity-based profiling of retaining glycosidases is advancing, though specific GH22-directed probes were discussed in general terms in the extracted context (gillaniUnknownyearunveilingtheproduction pages 9-9).
8) Current applications and implementations
- Food, medical, and environmental uses: Lysozyme is deployed as a food preservative (e.g., additive concentrations ~10–100 µg/ml; egg white contains ~3.2 mg/mL lysozyme), in antimicrobial packaging and water treatment membranes (e.g., chitosan–lysozyme nanofibers), and as part of therapeutic or prophylactic formulations (topicals, aerosols, lozenges) (matwiejczyk2025lysozymemonomerdimer pages 7-9, gillaniUnknownyearunveilingtheproduction pages 9-9).
- Synergy and combination therapies: Lysozyme synergizes with outer membrane permeabilizers and other antimicrobials to target Gram-negative bacteria and biofilms, a recurring strategy in applied research and translational studies (matwiejczyk2025lysozymemonomerdimer pages 2-3, matwiejczyk2025lysozymemonomerdimer pages 9-10).
9) Expert perspectives and analysis
- Conserved GH22 mechanism supports functional annotation: The presence of GH22 domains and lysozyme-like catalytic motifs provides strong evidence that Desmodus rotundus LYZ (K9IWH5) is a secreted muramidase participating in innate antibacterial defense, with a catalytic acid/base dyad and a retaining mechanism typical of c-type lysozymes (matwiejczyk2025lysozymemonomerdimer pages 3-5, matwiejczyk2025lysozymemonomerdimer pages 2-3).
- Substrate access determines spectrum: The Gram-positive bias is mechanistically explained by cell envelope accessibility; the outer membrane of Gram-negative bacteria necessitates permeabilization or engineered lysozyme variants to achieve robust activity. This explains the emphasis on conjugates, coatings, and synergy in current applications (matwiejczyk2025lysozymemonomerdimer pages 2-3, gillaniUnknownyearunveilingtheproduction pages 5-7, matwiejczyk2025lysozymemonomerdimer pages 9-10).
- Translational outlook: The 2023–2024 literature stresses anti-biofilm materials, diagnostic workflows leveraging peptidoglycan digestion, and protein engineering to expand spectrum and stability; these directions are directly compatible with a GH22 lysozyme such as K9IWH5 (matwiejczyk2025lysozymemonomerdimer pages 9-10, gillaniUnknownyearunveilingtheproduction pages 9-9).
10) Relevant statistics and quantitative data
- Source and usage levels: Egg white lysozyme content ~3.2 mg/mL; typical preservative concentrations ~10–100 µg/mL; examples of anti-biofilm coatings preventing S. aureus biofilms for >14 days and polymer membranes embedding ~16 µg lysozyme to suppress biofilms (matwiejczyk2025lysozymemonomerdimer pages 7-9, matwiejczyk2025lysozymemonomerdimer pages 9-10).
- Purification yields and specific activities: Example workflow shows stepwise purification to a final specific activity ~2000 U/mg with ~33% overall yield, illustrating achievable performance parameters for recombinant/isolated lysozyme preparations used in research and industry (gillaniUnknownyearunveilingtheproduction pages 3-5).
Organism- and record-specific conclusion
- LYZ (K9IWH5) from Desmodus rotundus is best annotated as a secreted c-type lysozyme (GH22 muramidase) that hydrolyzes the β(1→4) NAM–NAG linkage in peptidoglycan via a conserved catalytic dyad, contributing to innate antibacterial defense. While bat- and vampire bat–specific 2023–2024 experimental confirmations in saliva or serum were not recovered in the extracted evidence, the domain architecture and extensive conservation of GH22 lysozymes across mammals strongly support this functional assignment. Applications leveraging lysozyme’s activity—including anti-biofilm materials and analytical digestion of peptidoglycan—are rapidly advancing and directly relevant to the biochemical properties of K9IWH5 (matwiejczyk2025lysozymemonomerdimer pages 2-3, matwiejczyk2025lysozymemonomerdimer pages 3-5, gillaniUnknownyearunveilingtheproduction pages 5-7, gillaniUnknownyearunveilingtheproduction pages 3-5, matwiejczyk2025lysozymemonomerdimer pages 9-10).
Notes on URLs and publication dates
- Matwiejczyk et al., 2025, International Journal of Peptide Research and Therapeutics. URL: https://doi.org/10.1007/s10989-025-10742-x (matwiejczyk2025lysozymemonomerdimer pages 3-5, matwiejczyk2025lysozymemonomerdimer pages 2-3, matwiejczyk2025lysozymemonomerdimer pages 7-9, matwiejczyk2025lysozymemonomerdimer pages 9-10).
- Gillani et al., year not specified in excerpt (review). URL not available from extracted context (gillaniUnknownyearunveilingtheproduction pages 5-7, gillaniUnknownyearunveilingtheproduction pages 3-5, gillaniUnknownyearunveilingtheproduction pages 9-9).
Acknowledgment of limitations
- Bat-specific localization/expression evidence (e.g., saliva or neutrophil/Paneth cell data for D. rotundus) was not present in the extracted 2023–2024 evidence set. Where species-specific literature is limited, we have inferred function from GH22/c-type lysozyme domain knowledge and indicated this explicitly (matwiejczyk2025lysozymemonomerdimer pages 2-3, matwiejczyk2025lysozymemonomerdimer pages 3-5).
References
(matwiejczyk2025lysozymemonomerdimer pages 2-3): Magdalena Matwiejczyk, Aleksandra Zambrowicz, and Monika Besman. Lysozyme monomer, dimer, and oligomers: a review with a focus on immunological potential. International Journal of Peptide Research and Therapeutics, Jul 2025. URL: https://doi.org/10.1007/s10989-025-10742-x, doi:10.1007/s10989-025-10742-x. This article has 5 citations and is from a peer-reviewed journal.
(matwiejczyk2025lysozymemonomerdimer pages 3-5): Magdalena Matwiejczyk, Aleksandra Zambrowicz, and Monika Besman. Lysozyme monomer, dimer, and oligomers: a review with a focus on immunological potential. International Journal of Peptide Research and Therapeutics, Jul 2025. URL: https://doi.org/10.1007/s10989-025-10742-x, doi:10.1007/s10989-025-10742-x. This article has 5 citations and is from a peer-reviewed journal.
(gillaniUnknownyearunveilingtheproduction pages 5-7): SQ Gillani, K Waheed, S Najam, N Nadeem, and L Jameel. Unveiling the production, purification, and multifaceted potential of lysozymes: a review. Unknown journal, Unknown year.
(gillaniUnknownyearunveilingtheproduction pages 3-5): SQ Gillani, K Waheed, S Najam, N Nadeem, and L Jameel. Unveiling the production, purification, and multifaceted potential of lysozymes: a review. Unknown journal, Unknown year.
(matwiejczyk2025lysozymemonomerdimer pages 7-9): Magdalena Matwiejczyk, Aleksandra Zambrowicz, and Monika Besman. Lysozyme monomer, dimer, and oligomers: a review with a focus on immunological potential. International Journal of Peptide Research and Therapeutics, Jul 2025. URL: https://doi.org/10.1007/s10989-025-10742-x, doi:10.1007/s10989-025-10742-x. This article has 5 citations and is from a peer-reviewed journal.
(matwiejczyk2025lysozymemonomerdimer pages 9-10): Magdalena Matwiejczyk, Aleksandra Zambrowicz, and Monika Besman. Lysozyme monomer, dimer, and oligomers: a review with a focus on immunological potential. International Journal of Peptide Research and Therapeutics, Jul 2025. URL: https://doi.org/10.1007/s10989-025-10742-x, doi:10.1007/s10989-025-10742-x. This article has 5 citations and is from a peer-reviewed journal.
(gillaniUnknownyearunveilingtheproduction pages 9-9): SQ Gillani, K Waheed, S Najam, N Nadeem, and L Jameel. Unveiling the production, purification, and multifaceted potential of lysozymes: a review. Unknown journal, Unknown year.
There is a gene-specific paper, and it was not being used. The UniProt entry
lists three EMBL records; the third (MK561737 / QEQ43371.1, liver) carries
RX PubMed=31506780 — He et al. 2019, Adaptive Evolution of C-Type Lysozyme in
Vampire Bats. Fetched into the cache (abstract only; full_text_available:
false). Key points:
finding_review and turned into a knowledge gap rather than an annotation.The second salivary-gland EMBL record (JAA45151.1) traces to the Vampirome study
(PMID:23411029), which puts lysozyme in the accessory gland at both transcript
and protein level PMID:23411029 and detects it directly by LC-MS/MS PMID:23411029.
Reversed three annotation calls made by the previous version. All three were
in the direction of throwing information away:
GO:0050830 (Gram-positive) and GO:0050829 (Gram-negative) had been set toGO:0042742 defense response to bacterium. That generalises twoGO:0050830 is IDA (PMID:21093056), GO:0050829 is IBA — the same TreeGrafterGO:0031640 killing of cells of another organism had been markedFilled a missing GO aspect. The GOA record has no cellular component term at
all. Added GO:0005576 extracellular region as a NEW (ISS) annotation, supported
independently by the signal peptide (SIGNAL 1..18), by the human orthologue's
IDA annotation to the same term, and by proteomic detection in the bat gland.
gene_symbol changed from the accession to LYZ, matching both the UniProt
GN Name=LYZ line and the GOA SYMBOL column.
id: K9IWH5
gene_symbol: LYZ
product_type: PROTEIN
status: DRAFT
taxon:
id: NCBITaxon:9430
label: Desmodus rotundus
description: >-
LYZ is the single chicken-type (c-type) lysozyme of the common vampire bat, a
secreted glycoside hydrolase of family GH22 (EC 3.2.1.17). The 148-residue
precursor has a signal peptide (residues 1-18) and a cleaved 19-148 mature
chain that adopts the canonical lysozyme C fold. It hydrolyses the
beta-(1->4) linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine
in bacterial peptidoglycan, and between N-acetylglucosamine residues in
chitodextrins, degrading the cell wall and lysing the bacterium. Its
physiological setting is extracellular: it is a classical innate immune
effector of body fluids and secretions, and in D. rotundus it is one of the
antimicrobials that dominate the accessory submaxillary salivary gland, where
it was detected at both transcript and protein level, and it is also
transcribed in liver. Unlike insectivorous bats, which duplicated and
neofunctionalised lysozyme for chitin digestion, vampire bats retain a single
lysozyme gene; that gene carries a signature of positive selection on the
mature protein specific to the sanguivorous lineage, with substitutions
predicted to alter function, consistent with adaptation of antimicrobial
defence to a blood diet.
existing_annotations:
- term:
id: GO:0003796
label: lysozyme activity
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: >-
UniProt records the EC 3.2.1.17 reaction for this protein, it is
assigned to glycosyl hydrolase family 22, and PANTHER places it in
subfamily PTHR11407:SF28 LYSOZYME C. Muramidase activity is the core
molecular function.
action: ACCEPT
reason: >-
Catalytic activity statement, GH22 family assignment, and lysozyme C
subfamily assignment all agree. This is the defining activity of the
protein.
supported_by:
- &id_ec
reference_id: file:DESRO/K9IWH5/K9IWH5-uniprot.txt
supporting_text: >-
Hydrolysis of (1->4)-beta-linkages between N-acetylmuramic
- &id_gh22
reference_id: file:DESRO/K9IWH5/K9IWH5-uniprot.txt
supporting_text: 'Belongs to the glycosyl hydrolase 22 family.'
- term:
id: GO:0003824
label: catalytic activity
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
Root-level catalytic activity derived from the Hydrolase keyword. The
specific reaction is known and already annotated.
action: MODIFY
reason: Replace with the specific GO:0003796 lysozyme activity.
proposed_replacement_terms:
- id: GO:0003796
label: lysozyme activity
supported_by:
- *id_ec
- term:
id: GO:0016787
label: hydrolase activity
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
Keyword-derived parent term. The exact hydrolytic reaction is specified
in the UniProt catalytic activity block.
action: MODIFY
reason: Replace with the specific GO:0003796 lysozyme activity.
proposed_replacement_terms:
- id: GO:0003796
label: lysozyme activity
supported_by:
- *id_ec
- term:
id: GO:0016798
label: hydrolase activity, acting on glycosyl bonds
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
Keyword-derived intermediate parent. Correct but two levels more general
than the annotated EC 3.2.1.17 reaction.
action: MODIFY
reason: Replace with the specific GO:0003796 lysozyme activity.
proposed_replacement_terms:
- id: GO:0003796
label: lysozyme activity
supported_by:
- *id_ec
- *id_gh22
- term:
id: GO:0050830
label: defense response to Gram-positive bacterium
evidence_type: IEA
original_reference_id: GO_REF:0000118
review:
summary: >-
Gram-positive bacteria are the canonical target of c-type lysozymes,
because their thick peptidoglycan is directly accessible to the enzyme.
The human orthologue LYZ carries this annotation from direct assay
(IDA), and the TreeGrafter propagation to the bat protein is
appropriate. An earlier version of this review proposed replacing this
term with the broader GO:0042742; that would discard information, since
the general term is separately annotated and retained.
action: ACCEPT
reason: >-
This is the well-supported, mechanistically explained specificity of
c-type lysozyme, and the broad parent is annotated separately. Keep the
specific term.
supported_by:
- &id_bacteriolytic
reference_id: file:DESRO/K9IWH5/K9IWH5-uniprot.txt
supporting_text: 'Lysozymes have primarily a bacteriolytic function'
- &id_grampos
reference_id: file:DESRO/K9IWH5/K9IWH5-deep-research-falcon.md
supporting_text: >-
GH22 lysozymes prefer Gram-positive bacteria due to accessibility of
peptidoglycan, but they can exhibit activity against Gram-negative
bacteria when the outer membrane barrier is compromised
- term:
id: GO:0050829
label: defense response to Gram-negative bacterium
evidence_type: IEA
original_reference_id: GO_REF:0000118
review:
summary: >-
Activity against Gram-negative bacteria is the secondary, well-described
behaviour of mammalian c-type lysozymes: the outer membrane shields the
peptidoglycan, so killing requires permeabilisation, but the activity is
real and the human orthologue carries the same annotation by
phylogenetic inference. As with the Gram-positive term, an earlier
version of this review proposed generalising this to GO:0042742, which
would lose the distinction between the primary and secondary spectrum.
action: ACCEPT
reason: >-
Consistent with the characterised spectrum of mammalian c-type lysozyme
and with the same TreeGrafter propagation applied to the human
orthologue. Retained at the specific level.
supported_by:
- *id_grampos
- *id_bacteriolytic
- term:
id: GO:0042742
label: defense response to bacterium
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
The general antibacterial defence term, correct as the umbrella over the
two spectrum-specific terms above. Supported by the UniProt
Antimicrobial and Bacteriolytic enzyme keywords and by the description
of c-type lysozyme as an innate immune effector that kills bacteria by
degrading their cell wall peptidoglycan.
action: ACCEPT
reason: >-
Correct and directly supported. Retained as the general parent alongside
the specific Gram-positive and Gram-negative terms.
supported_by:
- *id_bacteriolytic
- &id_innate
reference_id: PMID:31506780
supporting_text: >-
killing bacteria by degrading peptidoglycan in their cell walls
reference_section_type: ABSTRACT
- term:
id: GO:0031640
label: killing of cells of another organism
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
This is precisely what a muramidase does: hydrolysing peptidoglycan
weakens the cell wall and lyses the bacterium. The human orthologue LYZ
carries this term from direct assay (IDA, PMID:9727055). An earlier
version of this review marked it as over-annotated on the grounds that
it is broad, but breadth is not the issue here - the term states the
outcome of the enzyme's own catalytic action.
action: ACCEPT
reason: >-
Bacteriolysis is the direct, demonstrated consequence of lysozyme
activity, not an inflated inference. The keyword source (Bacteriolytic
enzyme) is exactly on point.
supported_by:
- *id_innate
- reference_id: file:DESRO/K9IWH5/K9IWH5-deep-research-falcon.md
supporting_text: >-
thereby weakening the cell wall and causing osmotic lysis
- term:
id: GO:0005576
label: extracellular region
evidence_type: ISS
original_reference_id: file:DESRO/K9IWH5/K9IWH5-uniprot.txt
review:
summary: >-
Proposed new annotation. The GOA record for K9IWH5 carries no cellular
component term at all, which is a genuine gap: the precursor has a
SignalP-predicted signal peptide (1-18) with a cleaved 19-148 mature
chain, lysozyme is a classical secreted protein of body fluids, the
human orthologue is annotated to GO:0005576 from direct assay, and
lysozyme was recovered from the D. rotundus accessory submaxillary gland
by both transcriptome and proteome analysis.
action: NEW
reason: >-
Fills a missing aspect. The ISS evidence code rests on the sequence and
orthology basis recorded in the UniProt entry - the cleaved signal
peptide and the secreted human orthologue - which is why the reference
is the UniProt record rather than a publication. The Vampirome study is
retained as corroborating support, but its proteome was taken from
dissected gland tissue rather than secreted saliva, so it is not by
itself direct evidence of extracellular localisation.
supported_by:
- reference_id: file:DESRO/K9IWH5/K9IWH5-uniprot.txt
supporting_text: 'SIGNAL 1..18'
- reference_id: PMID:23411029
supporting_text: >-
families were expressed at higher levels in the AC gland, as
indicated by both transcriptome and proteome analysis (Figure 2B).
reference_section_type: RESULTS
- reference_id: file:DESRO/K9IWH5/K9IWH5-deep-research-falcon.md
supporting_text: >-
These features support extracellular localization (secreted protein)
as primary functional context.
references:
- id: GO_REF:0000043
title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
findings:
- statement: >-
The Hydrolase, Glycosidase, Antimicrobial, and Bacteriolytic enzyme
keywords are the source of the catalytic activity, hydrolase activity,
hydrolase activity acting on glycosyl bonds, defense response to
bacterium, and killing of cells of another organism annotations.
supporting_text: 'Bacteriolytic enzyme {ECO:0000256|ARBA:ARBA00022638};'
- id: GO_REF:0000118
title: TreeGrafter-generated GO annotations
findings:
- statement: >-
The Gram-positive and Gram-negative defence terms were propagated from
the PANTHER lysozyme C tree. The same propagation gives the human
orthologue its GO:0050829 annotation, and the human GO:0050830
annotation is additionally supported by direct assay.
supporting_text: 'PANTHER; PTHR11407:SF28; LYSOZYME C; 1.'
- id: GO_REF:0000120
title: Combined Automated Annotation using Multiple IEA Methods
findings:
- statement: >-
Lysozyme activity was assigned from the UniProtKB EC number 3.2.1.17.
supporting_text: 'EC=3.2.1.17 {ECO:0000256|ARBA:ARBA00012732};'
- id: PMID:31506780
title: Adaptive Evolution of C-Type Lysozyme in Vampire Bats.
full_text_unavailable: true
findings:
- statement: >-
Mammalian c-type lysozymes are innate immune effectors that kill
bacteria by degrading the peptidoglycan of their cell walls. This is
the general statement of function against which the vampire bat gene
was analysed.
supporting_text: >-
killing bacteria by degrading peptidoglycan in their cell walls
reference_section_type: ABSTRACT
- statement: >-
The common vampire bat, like the other phyllostomid bats analysed, has
a single c-type lysozyme gene - in contrast to the insectivorous bat
clade in which lysozyme was duplicated and adapted for chitin
digestion. This constrains functional interpretation of K9IWH5: there
is no paralogue to which a digestive role could be partitioned.
supporting_text: >-
Only a single lysozyme gene was identified in each of these species.
reference_section_type: ABSTRACT
- statement: >-
Positive selection was detected on the mature lysozyme along the
lineages leading to vampire bats but not in other single-copy bats,
and several sanguivore-specific substitutions are predicted to have
functional impacts.
supporting_text: >-
Evidence for positive selection on mature lysozyme was found on
lineages leading to vampire bats
reference_section_type: ABSTRACT
- statement: >-
The authors interpret this adaptation as antimicrobial rather than
digestive, driven by the specialised sanguivorous habits of vampire
bats.
supporting_text: >-
Functional adaptation of vampire bat lysozymes could be associated with
anti-microbial defense, possibly driven by the specialized
sanguivory-related habits of vampire bats.
reference_section_type: ABSTRACT
finding_review:
finding_status: CURRENT
review_notes: >-
Stated by the authors as an interpretation of the selection
analysis, not as a measured activity. No enzymatic or antibacterial
assay of vampire bat lysozyme is reported.
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: >-
PubMed-verified. This is the study behind the third EMBL record in the
UniProt entry (MK561737 / QEQ43371.1, liver), and it is the only
publication that analyses this specific gene. Only the abstract is
cached (full_text_available: false), so all statements used here are
drawn from the abstract; the sequence-level substitution analysis is not
available for inspection.
- id: PMID:23411029
title: 'The "Vampirome": Transcriptome and proteome analysis of the principal
and accessory submaxillary glands of the vampire bat Desmodus rotundus, a
vector of human rabies.'
findings:
- statement: >-
Lysozyme is one of the antimicrobials that dominate the accessory
submaxillary gland of D. rotundus, expressed there at higher levels
than in the principal gland and confirmed by both transcriptome and
proteome analysis. This is the study behind the salivary gland EMBL
record (JAA45151.1) in the UniProt entry.
supporting_text: >-
families were expressed at higher levels in the AC gland, as indicated
by both transcriptome and proteome analysis (Figure 2B).
reference_section_type: RESULTS
- statement: >-
Lysozyme was also among the proteins directly identified by LC-MS/MS
in the gland proteome, establishing that the protein - not only the
transcript - is present in the secretory tissue.
supporting_text: >-
components of the complement pathway, galectins, lysozyme, lipases
reference_section_type: RESULTS
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: >-
PubMed-verified, full text available via PMC. Establishes salivary gland
expression and proteomic detection of lysozyme in D. rotundus, which is
what supports the proposed extracellular region annotation.
- id: file:DESRO/K9IWH5/K9IWH5-uniprot.txt
title: UniProtKB record for K9IWH5 (K9IWH5_DESRO)
findings:
- statement: >-
The gene is named LYZ, the protein carries EC 3.2.1.17 with the
explicit muramidase reaction, and it belongs to glycosyl hydrolase
family 22 (PANTHER subfamily PTHR11407:SF28 LYSOZYME C).
supporting_text: 'Name=LYZ {ECO:0000313|EMBL:QEQ43371.1};'
- statement: >-
A SignalP-predicted signal peptide (1-18) is cleaved to give the mature
19-148 chain, consistent with a secreted protein.
supporting_text: 'SIGNAL 1..18'
- statement: >-
Three independent transcript sources underlie the entry: two vampire
bat submaxillary/salivary gland transcriptomes and one liver transcript
from the adaptive evolution study.
supporting_text: 'TISSUE=Submaxillary gland anterior and posterior lobes'
- id: file:DESRO/K9IWH5/K9IWH5-deep-research-falcon.md
title: Deep research report on K9IWH5
findings:
- statement: >-
The Gram-positive preference of GH22 lysozymes is a matter of substrate
accessibility rather than catalytic specificity; the outer membrane of
Gram-negative bacteria must be compromised for robust activity.
supporting_text: >-
GH22 lysozymes prefer Gram-positive bacteria due to accessibility of
peptidoglycan, but they can exhibit activity against Gram-negative
bacteria when the outer membrane barrier is compromised
- statement: >-
The report notes that its functional assignment is a GH22 family
inference and supports extracellular localisation as the primary
functional context.
supporting_text: >-
These features support extracellular localization (secreted protein) as
primary functional context.
reference_review:
relevance: MEDIUM
correctness: UNVERIFIED
review_notes: >-
LLM-generated survey. Accurate and useful at the GH22 family level, and
appropriately explicit that no D. rotundus-specific experimental data
were recovered. It did not surface PMID:31506780, the one study that does
analyse this gene. Cited here only for family-level mechanism.
core_functions:
- description: >-
Secreted c-type (GH22) lysozyme that hydrolyses the beta-(1->4) bond
between N-acetylmuramic acid and N-acetyl-D-glucosamine in bacterial
peptidoglycan, degrading the cell wall and lysing the bacterium. It acts
extracellularly as an innate immune effector of body fluids, and in the
vampire bat is a dominant antimicrobial of the accessory submaxillary
salivary gland secretion.
supported_by:
- reference_id: file:DESRO/K9IWH5/K9IWH5-uniprot.txt
supporting_text: >-
Hydrolysis of (1->4)-beta-linkages between N-acetylmuramic
- reference_id: PMID:31506780
supporting_text: >-
killing bacteria by degrading peptidoglycan in their cell walls
reference_section_type: ABSTRACT
- reference_id: PMID:23411029
supporting_text: >-
families were expressed at higher levels in the AC gland, as indicated
by both transcriptome and proteome analysis (Figure 2B).
reference_section_type: RESULTS
molecular_function:
id: GO:0003796
label: lysozyme activity
directly_involved_in:
- id: GO:0042742
label: defense response to bacterium
- id: GO:0050830
label: defense response to Gram-positive bacterium
- id: GO:0031640
label: killing of cells of another organism
locations:
- id: GO:0005576
label: extracellular region
knowledge_gaps:
- gap_statement: >-
The functional consequence of the sanguivore-specific positively
selected substitutions in vampire bat lysozyme is undetermined: no
muramidase or bacteriolytic assay has been performed on the D.
rotundus enzyme, so it is unknown whether the substitutions alter
catalytic rate, pH optimum, salt tolerance, or antibacterial spectrum.
boundary: >-
What is established is that vampire bats carry a single c-type
lysozyme gene, that the mature protein shows evidence of positive
selection on the lineages leading to vampire bats but not in other
single-copy bats, and that several sanguivore-clade substitutions are
computationally predicted to have functional impacts. What is missing
is any measurement of the protein.
gap_kind:
- BIOLOGY
dark_aspect: RESIDUAL_SUBGAP
status: OPEN
significance: >-
Positive selection on an innate immune enzyme in a lineage that feeds
on an open wound is the kind of adaptation that predicts an altered
antibacterial spectrum; confirming it would turn a family-level
annotation into a species-specific one, and would say what selective
pressure sanguivory imposes on innate immunity.
resolution: >-
Express recombinant D. rotundus lysozyme and a reconstructed ancestral
phyllostomid lysozyme, and compare turbidimetric muramidase rate on
Micrococcus lysodeikticus cell walls, pH and ionic-strength optima, and
minimum inhibitory concentrations against oral and blood-borne
bacteria.
provenance:
- reference_id: PMID:31506780
supporting_text: >-
several amino acid substitutions found in mature lysozymes from the
sanguivorous clade are predicted to have functional impacts
reference_section_type: ABSTRACT
- gap_statement: >-
It is undetermined whether vampire bat lysozyme has a digestive role on
the ingested blood meal in addition to its antimicrobial role.
boundary: >-
In insectivorous bats, lysozyme was duplicated and adaptively evolved
for chitin digestion; vampire bats have only one copy, so any digestive
role would have to be carried by the same protein that performs innate
defence. The authors interpret the vampire bat selection signal as
antimicrobial, but this is an interpretation of a sequence analysis,
not a measurement.
gap_kind:
- BIOLOGY
dark_aspect: BP_DARK
status: OPEN
significance: >-
Distinguishing digestive from defensive adaptation determines which GO
biological process branch this gene belongs in, and is the direct
parallel to the well-studied ruminant and colobine stomach lysozymes.
resolution: >-
Measure lysozyme abundance and activity along the vampire bat digestive
tract (stomach and intestine) versus salivary gland, and test activity
of the recombinant enzyme at gastric pH.
provenance:
- reference_id: PMID:31506780
supporting_text: >-
Only a single lysozyme gene was identified in each of these species.
reference_section_type: ABSTRACT
suggested_questions:
- question: >-
Do the positively selected substitutions in vampire bat mature lysozyme
change its catalytic properties or antibacterial spectrum relative to
lysozymes of insectivorous and frugivorous phyllostomid bats?
experts:
- David M. Irwin
- Yang Liu
- question: >-
Is salivary lysozyme delivered to the host bite wound in amounts that
matter for wound microbiology, or does it act principally to protect the
bat's own oral cavity and ingested blood meal?
experts:
- Ivo M. B. Francischetti
- José M. C. Ribeiro
- question: >-
Why is lysozyme concentrated in the accessory rather than the principal
submaxillary gland, and does that compartmentalisation separate
antimicrobial from anti-hemostatic salivary functions?
suggested_experiments:
- hypothesis: >-
Sanguivore-specific substitutions in vampire bat lysozyme alter its
antibacterial spectrum or its activity under the ionic conditions of blood.
description: >-
Express recombinant D. rotundus LYZ alongside lysozyme from a frugivorous
phyllostomid and human LYZ; compare turbidimetric muramidase rates on
Micrococcus lysodeikticus cell walls across pH and NaCl gradients, and
determine minimum inhibitory concentrations against Gram-positive and
Gram-negative bacteria with and without an outer-membrane permeabiliser.
Test individual sanguivore-clade substitutions by site-directed mutagenesis
in the frugivorous background.
experiment_type: Recombinant enzymology with site-directed mutagenesis
- hypothesis: >-
Vampire bat lysozyme is secreted into saliva and reaches the host bite
site.
description: >-
Quantify lysozyme in saliva expectorated by feeding bats by targeted
parallel reaction monitoring mass spectrometry, and localise the protein
within accessory versus principal submaxillary gland sections by
immunohistochemistry.
experiment_type: Targeted proteomics and immunohistochemistry
- hypothesis: >-
In the absence of a duplicated paralogue, the single vampire bat lysozyme
also acts on the ingested blood meal in the digestive tract.
description: >-
Measure lysozyme transcript abundance and muramidase activity in stomach
and intestinal tissue and contents versus salivary gland, and assay the
recombinant enzyme for stability and activity at gastric pH and against
pepsin.
experiment_type: Tissue expression profiling with activity assay