GO:0050528 acyloxyacyl hydrolase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0050528 acyloxyacyl hydrolase activity is a molecular function that removes a secondary fatty acid from bacterial endotoxin (LPS), detoxifying it [1, 6].
• The enzyme acts on the 3-(acyloxy)acyl group of bacterial toxin, releasing a 3-hydroxyacyl group and a free fatty acid.
• AOAH activity is best characterized in neutrophils, where it is reduced after parturition in cows [4, 7] and during coliform mastitis.
• In mice, AOAH modulates voiding activity, pelvic pain severity, and microglia-mediated pelvic pain.
• AOAH phospholipase activity can induce IL-22-producing CD1a-autoreactive T cells in psoriasis.
• AOAH protects the brain from experimental stroke by inactivating LPS.
Description
Acyloxyacyl hydrolase (AOAH) is a host enzyme that detoxifies bacterial lipopolysaccharide (LPS) by removing secondary acyl chains from the lipid A moiety [1, 6]. This molecular function, annotated as GO:0050528 acyloxyacyl hydrolase activity, is essential for controlling inflammatory responses to Gram-negative bacteria. The enzyme is highly expressed in neutrophils and macrophages, where it acts as a lipase to cleave fatty acids from the 3-(acyloxy)acyl group of bacterial toxin, yielding a 3-hydroxyacyl group and a free fatty acid. This reaction reduces the endotoxic potential of LPS and modulates immune signaling. Research on AOAH has expanded beyond endotoxin detoxification to include roles in pain regulation, voiding function, and neuroprotection [1, 3, 6, 8]. For example, AOAH regulates voiding activity in mice, and its phospholipase activity induces IL-22-producing CD1a-autoreactive T cells in psoriasis. In cows, neutrophil AOAH activity decreases after parturition and during coliform mastitis, linking the enzyme to periparturient immune suppression [4, 5, 7]. These findings highlight the importance of AOAH in host-microbe interactions and inflammatory disease. Understanding the molecular mechanism, regulation, and disease relevance of GO:0050528 is critical for researchers studying innate immunity, inflammation, and potential therapeutic interventions.
acyloxyacyl hydrolase activity At A Glance
| GO ID | GO:0050528 |
|---|---|
| GO term | acyloxyacyl hydrolase activity |
| Ontology | molecular_function |
| Synonym | (none) |
| Major function | Catalysis of the removal of a 3-(acyloxy)acyl group from bacterial toxin, releasing a 3-hydroxyacyl group and a fatty acid. |
| Substrate | Bacterial lipopolysaccharide (LPS) / lipid A [1, 6] |
| Product | 3-hydroxyacyl group of bacterial toxin + a fatty acid |
| Cellular location | Secreted and intracellular in neutrophils and macrophages [4, 5] |
| Physiological role | Detoxification of LPS, modulation of inflammation, pain, and voiding [1, 3, 6, 8] |
What Is GO:0050528?
GO:0050528 acyloxyacyl hydrolase activity is defined as the catalysis of the reaction: 3-(acyloxy)acyl group of bacterial toxin = 3-hydroxyacyl group of bacterial toxin + a fatty acid. In other words, it is a hydrolase activity that removes a secondary fatty acid from the lipid A portion of bacterial lipopolysaccharide, thereby detoxifying the endotoxin [1, 6].
Why Is acyloxyacyl hydrolase activity Important in Cell Biology?
Acyloxyacyl hydrolase activity is a key host defense mechanism against Gram-negative bacterial infections. By deacylating LPS, AOAH reduces the endotoxic load and prevents excessive inflammatory responses that can lead to sepsis, tissue damage, and chronic pain [1, 6, 8]. The enzyme also plays a role in immune cell activation, as its phospholipase activity can generate lipid antigens that stimulate autoreactive T cells in psoriasis. In veterinary medicine, reduced AOAH activity in neutrophils after parturition is associated with increased susceptibility to coliform mastitis [4, 5, 7]. Furthermore, AOAH protects the brain from experimental stroke by inactivating LPS, suggesting a neuroprotective role. Thus, understanding GO:0050528 is important for immunology, infectious disease, neuroscience, and reproductive biology.
• Detoxifies bacterial LPS, reducing endotoxic shock and inflammation [1, 6].
• Regulates voiding activity and pelvic pain severity in mice [1, 8].
• Modulates microglia-mediated pelvic pain.
• Induces IL-22-producing CD1a-autoreactive T cells in psoriasis.
• Reduced activity in neutrophils after parturition in cows [4, 7].
• Associated with coliform mastitis in cattle.
• Protects the brain from experimental stroke.
• Potential target for anti-inflammatory therapies [1, 6].
• Involved in host-microbe interactions and innate immunity [1, 2].
• Biomarker for periparturient immune status in dairy cows [4, 7].
Molecular Mechanism of acyloxyacyl hydrolase activity
Substrate recognition and binding
In simple terms: AOAH recognizes and binds to bacterial endotoxin (LPS).
Acyloxyacyl hydrolase (AOAH) specifically binds to the lipid A moiety of bacterial lipopolysaccharide (LPS), which contains 3-(acyloxy)acyl groups. The enzyme's active site accommodates the secondary acyl chains, positioning them for hydrolysis. This binding is essential for the subsequent deacylation reaction [1, 6].
Catalytic hydrolysis
In simple terms: AOAH cuts off a fatty acid from the endotoxin molecule.
The catalytic mechanism involves hydrolysis of the ester bond linking the 3-(acyloxy)acyl group to the lipid A backbone, releasing a 3-hydroxyacyl group and a free fatty acid. This reaction reduces the number of acyl chains on lipid A, converting the highly endotoxic LPS into a less toxic form [1, 6].
Cofactors and regulation
In simple terms: AOAH needs specific conditions and may be regulated by other proteins.
AOAH activity is optimal at neutral to slightly alkaline pH and requires calcium ions for full activity. The enzyme is regulated at the level of expression and secretion, particularly in neutrophils and macrophages [4, 5]. In cows, AOAH activity decreases after parturition, suggesting hormonal or metabolic regulation [4, 7].
Biological consequences
In simple terms: Removing fatty acids from endotoxin reduces inflammation and pain.
Deacylation of LPS by AOAH reduces its ability to activate Toll-like receptor 4 (TLR4) signaling, thereby dampening inflammatory cytokine production [1, 6]. This leads to reduced pain and improved voiding function in mouse models [1, 3, 8]. Additionally, AOAH-generated lipid antigens can stimulate CD1a-autoreactive T cells, linking the enzyme to psoriasis.
Key Genes Involved in GO:0050528 acyloxyacyl hydrolase activity
The following genes and proteins are directly involved in or regulate acyloxyacyl hydrolase activity (GO:0050528).
| Gene | Major Role | Research Relevance |
|---|---|---|
| AOAH | Encodes acyloxyacyl hydrolase, the enzyme responsible for deacylating LPS [1, 6] | Central to studies of endotoxin detoxification, pain, and neuroprotection [1, 3, 6, 8] |
| TLR4 | Recognizes LPS; AOAH reduces TLR4 activation by deacylation [1, 6] | Links AOAH activity to innate immune signaling [1, 6] |
| CD1A | Presents lipid antigens generated by AOAH to T cells | Implicated in psoriasis and autoreactive T cell responses |
| IL22 | Cytokine produced by CD1a-autoreactive T cells upon AOAH phospholipase activity | Marker of AOAH-mediated immune activation in psoriasis |
| LYZ | Lysozyme, often co-expressed with AOAH in neutrophils [4, 5] | Marker of neutrophil activation in mastitis |
| ITGAM | Integrin subunit alpha M, neutrophil marker [4, 5] | Used to isolate neutrophils for AOAH activity assays [4, 5] |
| CSF3R | G-CSF receptor, regulates neutrophil production | May influence AOAH levels in circulation |
| CXCL8 | Neutrophil chemoattractant | Associated with inflammatory response in mastitis |
| TNF | Pro-inflammatory cytokine [1, 6] | Downstream of LPS signaling; AOAH reduces its induction [1, 6] |
| IL1B | Pro-inflammatory cytokine [1, 6] | Reduced by AOAH-mediated LPS detoxification [1, 6] |
| IL6 | Pro-inflammatory cytokine [1, 6] | Modulated by AOAH activity [1, 6] |
| NLRP3 | Inflammasome sensor | May be affected by AOAH-mediated reduction of LPS |
| CASP1 | Inflammasome caspase | Downstream of NLRP3; influenced by AOAH |
| GSDMD | Gasdermin D, mediator of pyroptosis | Potential link to AOAH-mediated neuroprotection |
| P2RY12 | Microglial receptor | Involved in microglia-mediated pelvic pain modulated by AOAH |
| BDNF | Neurotrophin | May be affected by AOAH in pain pathways |
| TRPV1 | Pain receptor | Potential target of AOAH-mediated pain modulation |
| PIEZO2 | Mechanosensitive ion channel | Linked to voiding activity regulated by AOAH |
How Is acyloxyacyl hydrolase activity Regulated?
Acyloxyacyl hydrolase activity is regulated at multiple levels. In neutrophils, AOAH activity decreases after parturition in cows, likely due to hormonal changes [4, 7]. During coliform mastitis, AOAH activity in blood neutrophils changes dynamically, suggesting regulation by inflammatory mediators. In mice, AOAH expression in microglia is modulated during pelvic pain, and its activity influences pain severity [3, 8]. The enzyme's phospholipase activity can be induced in psoriasis, leading to CD1a-autoreactive T cell activation. Additionally, AOAH protects the brain from stroke, indicating that its activity may be regulated by ischemic conditions.
acyloxyacyl hydrolase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| AOAH | Pelvic pain and voiding dysfunction [1, 8] | AOAH knockout mice [1, 8] |
| AOAH | Psoriasis | Human keratinocyte and T cell co-cultures |
| AOAH | Ischemic stroke | Middle cerebral artery occlusion in AOAH-/- mice |
| AOAH | Coliform mastitis in cows [4, 5, 7] | Bovine neutrophil isolation and activity assays [4, 5, 7] |
| AOAH | Microglia-mediated pelvic pain | Microglia-specific AOAH knockout mice |
Acyloxyacyl hydrolase activity in inflammatory pain and voiding dysfunction
AOAH regulates voiding activity and pelvic pain severity in mice. Reduced AOAH activity is associated with increased pain and voiding dysfunction, while its presence alleviates these symptoms [1, 8]. Microglia-mediated pelvic pain is also modulated by AOAH, suggesting a role in neuroimmune interactions.
Acyloxyacyl hydrolase activity in psoriasis
The phospholipase activity of AOAH can induce IL-22-producing CD1a-autoreactive T cells in individuals with psoriasis. This suggests that AOAH may contribute to the pathogenesis of psoriasis by generating lipid antigens that activate autoreactive T cells.
Acyloxyacyl hydrolase activity in stroke and neuroprotection
AOAH protects the brain from experimental stroke by inactivating LPS. Mice deficient in AOAH exhibit larger infarcts and increased inflammation after stroke, indicating a neuroprotective role for the enzyme.
Acyloxyacyl hydrolase activity in bovine mastitis
Reduced AOAH activity in circulating neutrophils from cows after parturition is associated with increased susceptibility to coliform mastitis. During endotoxin and coliform mastitis, AOAH activity changes, reflecting its role in the bovine immune response [4, 5, 7].
From acyloxyacyl hydrolase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does AOAH deficiency affect voiding function? | AOAH knockout mouse |
| Does AOAH modulate pelvic pain severity? | AOAH knockout mouse and pain behavioral assays |
| Does AOAH protect against stroke? | AOAH knockout mouse with middle cerebral artery occlusion |
| Does AOAH phospholipase activity induce autoreactive T cells? | Human CD1a-transfected cells and T cell activation assays |
| Does AOAH activity change during mastitis? | Bovine neutrophil isolation from cows with coliform mastitis |
| Does AOAH regulate microglial pain signaling? | Microglia-specific AOAH knockout mice |
How to Study the acyloxyacyl hydrolase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| AOAH activity assay | Enzymatic deacylation of LPS | Quantifying AOAH function in neutrophils [4, 5] |
| qRT-PCR | AOAH mRNA levels | Gene expression in tissues [1, 2] |
| RNA-seq | Transcriptome-wide expression | Identifying AOAH-regulated pathways [2, 3] |
| Western blot | AOAH protein levels | Protein expression in cells and tissues [1, 6] |
| Immunohistochemistry | AOAH localization | Tissue distribution studies [1, 6] |
| Flow cytometry | AOAH+ cell populations | Immune cell phenotyping [4, 5] |
| Behavioral assays | Voiding and pain responses | AOAH knockout mouse phenotyping [1, 8] |
| Stroke model | Infarct volume and neuroinflammation | Neuroprotection studies |
Enzymatic activity assays
AOAH activity is typically measured using radiolabeled LPS or lipid A substrates, followed by thin-layer chromatography to separate deacylated products [1, 4, 5]. These assays are used to quantify enzyme activity in neutrophil lysates or recombinant protein preparations [4, 5, 7].
Gene expression analysis
Quantitative RT-PCR and RNA-seq are used to measure AOAH mRNA levels in tissues and cells, such as neutrophils, microglia, and keratinocytes [1, 2, 3]. These methods help correlate AOAH expression with disease states [2, 3].
Protein detection and localization
Western blotting and immunohistochemistry are employed to detect AOAH protein and determine its cellular localization in tissues [1, 6]. Flow cytometry can identify AOAH-expressing immune cell populations [4, 5].
Animal models and behavioral assays
AOAH knockout mice are used in behavioral assays for voiding function and pain sensitivity [1, 3, 8]. Stroke models involve middle cerebral artery occlusion followed by infarct size measurement.
How CRISPR Can Be Used to Study GO:0050528 acyloxyacyl hydrolase activity
Knockout
CRISPR-Cas9 knockout of AOAH in cell lines or mice can abolish acyloxyacyl hydrolase activity, enabling studies of its role in LPS detoxification, pain, and neuroprotection [1, 6, 8]. Knockout models are essential for establishing causality.
Point Mutation
Introducing point mutations in the AOAH catalytic domain can dissect the enzymatic mechanism and separate its lipase activity from other functions, such as phospholipase activity in psoriasis.
Knock-in
Knock-in of tagged AOAH (e.g., FLAG or GFP) allows for tracking protein localization and interaction partners in live cells and tissues [1, 3].
Overexpression
Overexpression of AOAH in cell lines or transgenic mice can enhance LPS detoxification and may protect against inflammatory diseases, providing a gain-of-function complement to knockout studies.
How EDITGENE Supports acyloxyacyl hydrolase activity Research
Researchers studying acyloxyacyl hydrolase activity-related genes often need to determine whether a candidate gene is causally involved in LPS detoxification, inflammation, or pain. EDITGENE provides comprehensive CRISPR services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for acyloxyacyl hydrolase activity research.
Frequently Asked Questions About acyloxyacyl hydrolase activity
What is acyloxyacyl hydrolase activity?
Acyloxyacyl hydrolase activity (GO:0050528) is a molecular function that removes a secondary fatty acid from bacterial endotoxin (LPS), detoxifying it [1, 6].
What genes are involved in acyloxyacyl hydrolase activity?
The primary gene is AOAH, which encodes the enzyme. Other genes such as TLR4, CD1A, and IL22 are involved in downstream signaling [1, 2, 6].
What diseases are associated with acyloxyacyl hydrolase activity?
It is associated with inflammatory pain, voiding dysfunction, psoriasis, stroke, and bovine mastitis [1, 2, 3, 6, 8].
How is acyloxyacyl hydrolase activity measured?
It is measured using enzymatic assays with radiolabeled LPS, qRT-PCR for AOAH mRNA, and Western blot for protein levels [1, 4, 5].
What is the role of AOAH in the immune system?
AOAH detoxifies LPS, reducing TLR4 activation and inflammatory cytokine production, thereby modulating innate immunity [1, 6].
Does acyloxyacyl hydrolase activity affect pain?
Yes, AOAH regulates pelvic pain severity and microglia-mediated pain in mouse models [3, 8].
Can acyloxyacyl hydrolase activity be targeted for therapy?
It is a potential target for anti-inflammatory therapies, particularly in sepsis, stroke, and chronic pain [1, 6, 8].
What are the substrates of acyloxyacyl hydrolase?
The substrate is bacterial lipopolysaccharide (LPS), specifically the lipid A moiety containing 3-(acyloxy)acyl groups [1, 6].
How is acyloxyacyl hydrolase activity regulated?
It is regulated by hormonal changes after parturition, inflammatory mediators during mastitis, and ischemic conditions in stroke [4, 5, 6, 7].
What model organisms are used to study acyloxyacyl hydrolase activity?
Mice (AOAH knockout) and cows (neutrophil assays) are commonly used [1, 4, 5, 6, 8].
Conclusion
Acyloxyacyl hydrolase activity (GO:0050528) is a critical enzymatic function that detoxifies bacterial LPS and modulates inflammation, pain, and neuroprotection. Its role in diverse biological processes, from immune defense to psoriasis and stroke, underscores its importance as a research target. Understanding the molecular mechanism, regulation, and disease associations of AOAH can lead to new therapeutic strategies for inflammatory and infectious diseases. EDITGENE provides advanced CRISPR tools to accelerate this research.
References
- 1. Aguiniga LM et al.. 2020. Acyloxyacyl hydrolase regulates voiding activity.. Am J Physiol Renal Physiol 318(4):F1006-F1016 PMID: 32003596
- 2. Singh R et al.. 2022. Phospholipase activity of acyloxyacyl hydrolase induces IL-22-producing CD1a-autoreactive T cells in individuals with psoriasis.. Eur J Immunol 52(3):511-524 PMID: 34913478
- 3. Rahman-Enyart A et al.. 2022. Acyloxyacyl hydrolase regulates microglia-mediated pelvic pain.. PLoS One 17(8):e0269140 PMID: 35980963
- 4. Dosogne H et al.. 1998. Reduction of acyloxyacyl hydrolase activity in circulating neutrophils from cows after parturition.. J Dairy Sci 81(3):672-7 PMID: 9565869
- 5. Mehrzad J et al.. 2007. Bovine blood neutrophil acyloxyacyl hydrolase (AOAH) activity during endotoxin and coliform mastitis.. Vet Res 38(5):655-68 PMID: 17583663
- 6. Zhu Y et al.. 2024. The LPS-inactivating enzyme acyloxyacyl hydrolase protects the brain from experimental stroke.. Transl Res 270:42-51 PMID: 38522823
- 7. Dosogne H et al.. 1999. Acyloxyacyl hydrolase activity of neutrophil leukocytes in normal early postpartum dairy cows and in cows with retained placenta.. Theriogenology 51(5):867-74 PMID: 10729009
- 8. Yang W et al.. 2018. Acyloxyacyl hydrolase modulates pelvic pain severity.. Am J Physiol Regul Integr Comp Physiol 314(3):R353-R365 PMID: 29118019
