GO:0045730 respiratory burst: Oxidative Burst Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0045730 respiratory burst is a biological process of elevated oxygen consumption that produces hydrogen peroxide (H2O2), superoxide anions and hydroxyl radicals through an NADH-dependent system.
• In human neutrophils, the respiratory burst is the primary mechanism for killing ingested microbes and is driven by the NADPH oxidase complex.
• Defects in the respiratory burst oxidase cause chronic granulomatous disease, characterized by recurrent bacterial and fungal infections.
• The respiratory burst is not limited to immune cells; plant respiratory burst oxidase homologs (RBOHs) generate reactive oxygen species for stress responses and development.
• Respiratory burst activity is tightly regulated by assembly of cytosolic and membrane components, and can be modulated by ions such as zinc and by flavonoids.
• Research on respiratory burst spans immunology, plant biology, and inflammation, using neutrophils, macrophages, and ovine models to study its function.
Description
The respiratory burst, formally annotated as GO:0045730, is a biological process defined by a phase of elevated metabolic activity during which oxygen consumption increases, leading to the production of hydrogen peroxide (H2O2), superoxide anions and hydroxyl radicals by an NADH-dependent system. This process is best known in phagocytic cells such as neutrophils and macrophages, where it constitutes a central antimicrobial mechanism. The term is also referred to as the metabolic burst or oxidative burst, reflecting its rapid and intense nature. Understanding respiratory burst is critical for researchers in immunology, infectious disease, and cell biology because it links cellular metabolism to host defense and oxidative signaling. In addition to its role in mammals, respiratory burst-like processes occur in plants through respiratory burst oxidase homologs (RBOHs), which produce reactive oxygen species (ROS) in response to stress and during development. The respiratory burst is thus a conserved and versatile process with broad biological significance.
respiratory burst At A Glance
| GO ID | GO:0045730 |
|---|---|
| GO term | respiratory burst |
| Ontology | biological_process |
| Synonym | metabolic burst, oxidative burst |
| Definition | A phase of elevated metabolic activity, during which oxygen consumption increases; this leads to the production, by an NADH dependent system, of hydrogen peroxide (H2O2), superoxide anions and hydroxyl radicals. |
| Major function | Production of reactive oxygen species for antimicrobial defense and cellular signaling. |
| Key enzymes | NADPH oxidase complex (e.g., CYBB/NOX2, CYBA, NCF1, NCF2, NCF4). |
| Cellular location | Plasma membrane and phagosomal membrane of phagocytes. |
| Related processes | Innate immune response, oxidative stress, plant stress responses. |
What Is GO:0045730?
According to the Gene Ontology, respiratory burst (GO:0045730) is a phase of elevated metabolic activity, during which oxygen consumption increases; this leads to the production, by an NADH dependent system, of hydrogen peroxide (H2O2), superoxide anions and hydroxyl radicals. In simpler terms, it is a rapid burst of oxygen consumption that generates reactive oxygen species for defense or signaling.
Why Is respiratory burst Important in Cell Biology?
The respiratory burst is essential for host defense against microbial pathogens, and its dysfunction leads to severe immunodeficiency, as seen in chronic granulomatous disease. Beyond immunity, respiratory burst-derived ROS participate in cell signaling, inflammation, and plant stress responses, making it a focal point for understanding redox biology in health and disease.
• Provides the primary antimicrobial mechanism in neutrophils and macrophages.
• Defects in the respiratory burst oxidase cause chronic granulomatous disease, a life-threatening immunodeficiency.
• Respiratory burst-derived ROS act as signaling molecules in inflammation and immune regulation.
• In plants, respiratory burst oxidase homologs mediate stress responses and developmental processes.
• The process is implicated in inflammatory skin diseases such as psoriasis, where neutrophils contribute to pathology.
• Respiratory burst activity can be modulated by dietary compounds like flavonoids, suggesting therapeutic avenues.
• Zinc ions accelerate respiratory burst termination, highlighting metal ion regulation of the process.
• Ovine neutrophils provide a comparative model for studying respiratory burst function across species.
• Understanding respiratory burst is key to developing anti-inflammatory and immunomodulatory drugs.
• The process is a target for research in oxidative stress-related diseases and aging.
What Happens During respiratory burst?
Activation and Assembly of the NADPH Oxidase Complex
In simple terms: The cell assembles a molecular machine on its membrane to start producing reactive oxygen species.
In resting phagocytes, the NADPH oxidase components are distributed between the cytosol and membranes. Upon activation by stimuli such as bacteria or inflammatory signals, cytosolic subunits including NCF1 (p47phox), NCF2 (p67phox), and NCF4 (p40phox) translocate to the membrane, where they associate with the membrane-bound heterodimer of CYBB (NOX2) and CYBA (p22phox). This assembly is a prerequisite for electron transfer and superoxide production.
Electron Transfer and Superoxide Generation
In simple terms: The assembled machine uses NADPH to convert oxygen into superoxide, a reactive oxygen molecule.
The activated NADPH oxidase complex catalyzes the transfer of electrons from cytosolic NADPH to molecular oxygen, generating superoxide anions (O2-). This reaction is electrogenic, and the resulting superoxide is released into the phagosome or extracellular space. The rapid consumption of oxygen during this phase is the hallmark of the respiratory burst.
Production of Hydrogen Peroxide and Hydroxyl Radicals
In simple terms: Superoxide is converted into other reactive molecules that are even more potent at killing microbes.
Superoxide anions spontaneously or enzymatically dismutate to hydrogen peroxide (H2O2), which can then participate in reactions generating hydroxyl radicals (OH•). These reactive oxygen species (ROS) collectively damage microbial DNA, proteins, and lipids, contributing to pathogen killing. The production of H2O2 and hydroxyl radicals is a key outcome of the respiratory burst as defined by GO:0045730.
Termination and Regulation of the Burst
In simple terms: The process is shut down to prevent damage to the host cell.
The respiratory burst is transient and tightly regulated. Termination involves disassembly of the oxidase complex and degradation of ROS by antioxidant systems. Zinc ions have been shown to accelerate the termination of the respiratory burst in human polymorphonuclear neutrophils (PMN), suggesting a role for metal ions in modulating the duration of the burst. Flavonoids can inhibit the respiratory burst, providing a means of pharmacological control.
Key Genes Involved in GO:0045730 respiratory burst
The following genes and proteins are central to the respiratory burst process, based on their established roles in the NADPH oxidase complex and related pathways.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CYBB | Encodes NOX2, the catalytic subunit of NADPH oxidase | Mutations cause X-linked chronic granulomatous disease |
| CYBA | Encodes p22phox, membrane subunit of NADPH oxidase | Essential for oxidase stability and function |
| NCF1 | Encodes p47phox, cytosolic subunit | Defects cause autosomal recessive CGD |
| NCF2 | Encodes p67phox, cytosolic subunit | Required for electron transfer |
| NCF4 | Encodes p40phox, cytosolic subunit | Regulates oxidase assembly |
| RAC1 | Small GTPase, participates in oxidase activation | Modulates respiratory burst in phagocytes |
| RAC2 | Small GTPase, participates in oxidase activation | Important for neutrophil function |
| RBOHD | Plant respiratory burst oxidase homolog | Mediates ROS production in plant stress responses |
| RBOHF | Plant respiratory burst oxidase homolog | Involved in plant immunity and development |
| MPO | Myeloperoxidase, generates hypochlorous acid from H2O2 | Enhances microbial killing |
| SOD1 | Superoxide dismutase 1, converts superoxide to H2O2 | Modulates ROS levels |
| SOD2 | Mitochondrial superoxide dismutase | Protects against oxidative stress |
| CAT | Catalase, detoxifies H2O2 | Regulates ROS homeostasis |
| GPX1 | Glutathione peroxidase 1, reduces H2O2 | Antioxidant defense |
| TLR4 | Toll-like receptor 4, activates respiratory burst | Links innate immunity to ROS production |
| FCGR2A | Fc gamma receptor, triggers phagocytosis and burst | Antibody-mediated activation |
| ITGB2 | Integrin beta 2, adhesion-dependent activation | Modulates neutrophil burst |
| PRTN3 | Proteinase 3, neutrophil serine protease | May influence respiratory burst |
How Is respiratory burst Regulated?
The respiratory burst is regulated at multiple levels. Activation requires phosphorylation of cytosolic subunits and assembly of the NADPH oxidase complex. Small GTPases such as RAC1 and RAC2 are essential for activation. Termination is mediated by disassembly and by antioxidant systems, and can be accelerated by zinc ions. Pharmacological inhibition by flavonoids demonstrates that the process can be modulated externally. In plants, RBOH activity is regulated by calcium and phosphorylation.
respiratory burst and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CYBB | Chronic granulomatous disease | Knockout mouse or human iPSC-derived neutrophils |
| NCF1 | Chronic granulomatous disease | Point-mutation knock-in in cell lines |
| RAC2 | Neutrophil immunodeficiency | Knockout zebrafish or mouse models |
| RBOHD | Plant immunity and stress | Arabidopsis knockout mutants |
| MPO | Inflammatory disorders | Overexpression in myeloid cell lines |
Chronic Granulomatous Disease (CGD)
Chronic granulomatous disease is a primary immunodeficiency caused by mutations in genes encoding NADPH oxidase components, including CYBB, CYBA, NCF1, NCF2, and NCF4. Affected individuals suffer from recurrent and severe bacterial and fungal infections due to defective respiratory burst in phagocytes. The disease highlights the critical role of the respiratory burst in host defense.
Psoriasis and Inflammatory Skin Diseases
Neutrophils in psoriasis exhibit enhanced respiratory burst activity, contributing to oxidative stress and inflammation in the skin. Targeting neutrophil respiratory burst may offer therapeutic benefits in psoriasis and related inflammatory conditions.
Plant Stress and Immunity
Plant respiratory burst oxidase homologs (RBOHs) produce ROS during pathogen attack and abiotic stress, acting as signaling molecules for defense and acclimation. Dysregulation of RBOH activity can impair plant immunity and stress tolerance.
From respiratory burst-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X regulate respiratory burst? | CRISPR knockout in neutrophil-like HL-60 cells |
| Does a specific mutation affect oxidase assembly? | Point-mutation knock-in in PLB-985 cells |
| Can a tagged protein track oxidase dynamics? | Knock-in of fluorescent tag at endogenous locus |
| Does overexpression enhance ROS production? | Overexpression of CYBB in phagocytic cells |
| What is the role of RBOH in plant stress? | CRISPR knockout in Arabidopsis |
| How do flavonoids inhibit the burst? | Pharmacological treatment of primary neutrophils |
How to Study the respiratory burst Process
| Method | What It Measures | Typical Application |
|---|---|---|
| DHR oxidation assay | H2O2 production | Diagnosis of CGD |
| Cytochrome c reduction | Superoxide release | Neutrophil function testing |
| Chemiluminescence | ROS generation | High-throughput screening |
| CRISPR knockout | Gene function | Identifying essential oxidase components |
| Live-cell imaging | Spatiotemporal ROS dynamics | Phagosome maturation studies |
| RNA-seq | Transcriptional changes | Response to burst-inducing stimuli |
| Proteomics | Protein assembly and modifications | Oxidase complex composition |
| Plant stress assays | RBOH-mediated ROS | Arabidopsis immunity |
Measuring Respiratory Burst Activity
The respiratory burst is commonly measured by chemiluminescence, cytochrome c reduction, or dihydrorhodamine 123 (DHR) oxidation, which detect superoxide and hydrogen peroxide production. These assays are used to assess neutrophil function in health and disease.
Genetic and Pharmacological Manipulation
CRISPR-Cas9 knockout of NADPH oxidase genes in cell lines such as PLB-985 or HL-60 allows dissection of the respiratory burst pathway. Pharmacological inhibitors like flavonoids can be used to modulate the burst in primary cells.
Imaging and Live-Cell Analysis
Fluorescent probes and genetically encoded sensors enable real-time imaging of ROS production during phagocytosis. These methods reveal spatiotemporal dynamics of the respiratory burst.
Comparative and Plant Models
Ovine neutrophils provide a large-animal model for respiratory burst studies. Plant RBOH function is studied using Arabidopsis mutants and stress treatments.
How CRISPR Can Be Used to Study GO:0045730 respiratory burst
Knockout
CRISPR knockout of genes such as CYBB, NCF1, or RBOHD enables loss-of-function studies to determine their requirement for respiratory burst. Knockout cell lines can be used to measure ROS production and microbial killing.
Point Mutation
Point mutations identified in CGD patients can be introduced into cell lines to study their impact on oxidase assembly and activity. This approach helps distinguish pathogenic variants from benign polymorphisms.
Knock-in
Knock-in of fluorescent tags or reporter genes at endogenous loci allows tracking of NADPH oxidase components in live cells. This provides insights into protein localization and dynamics during the respiratory burst.
Overexpression
Overexpression of wild-type or mutant oxidase subunits can enhance or disrupt respiratory burst activity, facilitating structure-function studies. This is useful for testing gain-of-function variants.
How EDITGENE Supports respiratory burst Research
Researchers studying respiratory burst-related genes often need to determine whether a candidate gene is causally involved in ROS production, oxidase assembly, or immune defense. EDITGENE provides comprehensive CRISPR services to create precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for respiratory burst research.
Frequently Asked Questions About respiratory burst
What is respiratory burst (GO:0045730)?
Respiratory burst is a biological process of elevated oxygen consumption that produces hydrogen peroxide, superoxide anions, and hydroxyl radicals via an NADH-dependent system.
What genes are involved in respiratory burst?
Key genes include CYBB, CYBA, NCF1, NCF2, NCF4, RAC1, RAC2, and plant RBOH homologs.
What is the role of NADPH oxidase in respiratory burst?
NADPH oxidase is the enzyme complex that transfers electrons from NADPH to oxygen, generating superoxide during the respiratory burst.
How is respiratory burst measured?
It is measured by assays such as DHR oxidation, cytochrome c reduction, and chemiluminescence.
What diseases are associated with defective respiratory burst?
Chronic granulomatous disease is caused by defects in the respiratory burst oxidase, leading to recurrent infections.
Can respiratory burst be inhibited?
Yes, flavonoids and other compounds can inhibit the respiratory burst in neutrophils.
What is the difference between respiratory burst and oxidative burst?
They are synonyms; both refer to the same process of rapid ROS production.
Do plants have a respiratory burst?
Yes, plants use respiratory burst oxidase homologs (RBOHs) to produce ROS during stress and development.
How does zinc affect respiratory burst?
Zinc accelerates the termination of the respiratory burst in human neutrophils.
What model systems are used to study respiratory burst?
Neutrophils, macrophages, HL-60 cells, PLB-985 cells, and Arabidopsis are common models.
Conclusion
The respiratory burst (GO:0045730) is a fundamental biological process that bridges oxygen metabolism and host defense. Its dysregulation underlies severe immunodeficiency and contributes to inflammatory diseases, while in plants it plays key roles in stress responses. Continued research using advanced CRISPR models will further elucidate its mechanisms and therapeutic potential.
References
- 1. Dahlgren C et al.. 1999. Respiratory burst in human neutrophils.. J Immunol Methods 232(1-2):3-14 PMID: 10618505
- 2. Chiang CC et al.. 2019. Neutrophils in Psoriasis.. Front Immunol 10:2376 PMID: 31649677
- 3. Wang W et al.. 2018. Role of plant respiratory burst oxidase homologs in stress responses.. Free Radic Res 52(8):826-839 PMID: 29732902
- 4. Droste A et al.. 2021. Zinc accelerates respiratory burst termination in human PMN.. Redox Biol 47:102133 PMID: 34562872
- 5. Forman HJ et al.. 2001. Signaling by the respiratory burst in macrophages.. IUBMB Life 51(6):365-71 PMID: 11758804
- 6. Ciz M et al.. 2012. Flavonoids inhibit the respiratory burst of neutrophils in mammals.. Oxid Med Cell Longev 2012:181295 PMID: 22577489
- 7. Dinauer MC. 1993. The respiratory burst oxidase and the molecular genetics of chronic granulomatous disease.. Crit Rev Clin Lab Sci 30(4):329-69 PMID: 8110374
- 8. Tung JP et al.. 2009. Respiratory burst function of ovine neutrophils.. BMC Immunol 10:25 PMID: 19422720
