GO:0016670 oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0016670 describes a molecular function: the oxidation of sulfur-containing groups using oxygen as the terminal electron acceptor [1,3,4].
• Key enzymes include sulfide:quinone oxidoreductase (SQOR), sulfhydryl oxidases (e.g., Erv1/ALR), and sulfite oxidases, which are conserved from bacteria to humans [1,3,4,8].
• These enzymes are central to mitochondrial hydrogen sulfide detoxification, protein disulfide bond formation, and sulfur metabolism [3,6,7].
• Dysregulation is linked to neurodegeneration, cancer, and mitochondrial disease, making them attractive therapeutic targets [3,6].
• CRISPR knockout, point-mutation, and knock-in models are essential to dissect their catalytic mechanisms and physiological roles [1,3].
• EDITGENE provides custom cell models and screening services to accelerate research on GO:0016670-related genes.
Description
The Gene Ontology (GO) term GO:0016670, oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor, defines a class of enzymes that catalyze redox reactions where a sulfur-containing group (e.g., sulfide, sulfite, or protein thiols) is oxidized and molecular oxygen is reduced [1,3,4]. This activity is fundamental to cellular sulfur metabolism, mitochondrial function, and protein folding [3,6,7]. Enzymes with this activity are found across all domains of life and include sulfide:quinone oxidoreductase (SQOR), sulfhydryl oxidases such as Erv1/ALR, and sulfite oxidases [1,3,4,8]. Their catalytic mechanisms often involve flavin adenine dinucleotide (FAD) or molybdenum cofactors and generate reactive oxygen species or disulfide bonds as products [3,4,7]. Researchers study GO:0016670 to understand how cells detoxify hydrogen sulfide, maintain mitochondrial redox balance, and ensure proper protein folding [3,6]. Dysregulation of these enzymes has been implicated in neurodegenerative diseases, cancer, and mitochondrial disorders [3,6]. The availability of high-resolution structures and kinetic data has advanced mechanistic understanding, but the physiological roles of many family members remain unclear [1,3,4]. This article synthesizes authoritative QuickGO data and verified PubMed literature to provide a comprehensive overview of GO:0016670, covering its definition, biological significance, key genes, regulatory mechanisms, disease associations, and state-of-the-art research methods including CRISPR-based models.
oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor At A Glance
| GO ID | GO:0016670 |
|---|---|
| GO term | oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor |
| Ontology | molecular_function |
| Synonym | oxidoreductase activity, acting on sulphur group of donors, oxygen as acceptor |
| Major function | Catalyzes oxidation of sulfur-containing groups using oxygen as electron acceptor |
| EC number | 1.8.3.- |
| Examples | Sulfide:quinone oxidoreductase, sulfhydryl oxidase, sulfite oxidase |
| Cofactors | FAD, molybdenum, heme |
| Subcellular location | Mitochondria, cytoplasm, extracellular |
What Is GO:0016670?
GO:0016670 is a molecular function term describing catalysis of an oxidation-reduction (redox) reaction in which a sulfur-containing group acts as a hydrogen or electron donor and reduces oxygen. In other words, these enzymes transfer electrons from sulfur-containing substrates to molecular oxygen, producing oxidized sulfur species and water or reactive oxygen species. The term is specific to oxygen as the final electron acceptor, distinguishing it from other sulfur oxidoreductases that use different acceptors.
Why Is oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor Important in Cell Biology?
GO:0016670 is critical for cellular redox homeostasis, sulfur metabolism, and protein quality control. Enzymes with this activity protect cells from hydrogen sulfide toxicity, contribute to mitochondrial energy metabolism, and facilitate oxidative protein folding in the endoplasmic reticulum and mitochondrial intermembrane space [3,6,7]. Their dysfunction is associated with severe human pathologies, including Leigh syndrome, ethylmalonic encephalopathy, and cancer [3,6]. Understanding these enzymes at molecular and physiological levels is essential for developing targeted therapies.
• Detoxification of hydrogen sulfide, a gasotransmitter that is toxic at high concentrations.
• Maintenance of mitochondrial redox balance and ATP production.
• Facilitation of disulfide bond formation in secretory and mitochondrial proteins [1,7].
• Role in sulfur assimilation and energy metabolism in bacteria and archaea [2,5].
• Implication in neurodegenerative diseases such as Alzheimer's and Parkinson's.
• Association with cancer progression through altered redox signaling.
• Target for antimicrobial drug development in pathogens like Salmonella.
• Biotechnological applications in biosensors and industrial biocatalysis.
• Essential for embryonic development and tissue homeostasis.
• Provides a model system for studying oxygen activation and electron transfer.
What Happens During oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor?
Substrate Binding and Activation
In simple terms: The enzyme grabs a sulfur-containing molecule and prepares it for oxidation.
The catalytic cycle begins with binding of a sulfur-containing substrate, such as sulfide, sulfite, or a protein thiol, to the enzyme's active site. In sulfide:quinone oxidoreductase (SQOR), the substrate binds near a FAD cofactor, which is reduced by the sulfur group. Sulfhydryl oxidases like Erv1 use a redox-active disulfide to accept electrons from thiol substrates. Structural studies have revealed that substrate specificity is determined by the geometry and chemical environment of the active site [3,4].
Electron Transfer to Oxygen
In simple terms: Electrons stripped from sulfur are passed to oxygen, turning it into water or reactive species.
Following substrate oxidation, electrons are transferred through a series of cofactors (e.g., FAD, heme, iron-sulfur clusters) to molecular oxygen, the terminal electron acceptor. In SQOR, electrons flow from FAD to a quinone pool, but in the presence of oxygen, reactive oxygen species can be generated. Sulfite oxidase uses a molybdenum cofactor to transfer electrons to cytochrome c, but some family members directly reduce oxygen. The efficiency of electron transfer to oxygen varies among enzymes and is a key determinant of their physiological function.
Product Release and Enzyme Regeneration
In simple terms: After the reaction, the oxidized product leaves and the enzyme resets for another round.
The oxidized sulfur product (e.g., sulfate, disulfide, or sulfenic acid) is released from the active site, and the enzyme returns to its resting state. For sulfhydryl oxidases, the formation of a disulfide bond in a substrate protein is coupled to oxygen reduction, generating hydrogen peroxide. Erv1 regenerates its active site disulfide via a relay system involving cytochrome c. Kinetic analyses have shown that product release can be rate-limiting for some enzymes [1,4].
Regulation by Cellular Redox State
In simple terms: The cell's overall redox balance can speed up or slow down these enzymes.
The activity of GO:0016670 enzymes is modulated by the cellular redox environment, including the ratio of reduced to oxidized glutathione and the availability of NAD(P)H. For example, the MIA pathway, which includes Erv1, is regulated by the oxidative folding state in the mitochondrial intermembrane space. In bacteria, respiratory pathways for sulfur compound reduction are induced under anaerobic conditions and repressed by oxygen. These regulatory mechanisms ensure that sulfur oxidation is coordinated with cellular metabolic demands.
Key Genes Involved in GO:0016670 oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor
The following genes encode enzymes with GO:0016670 activity, as supported by published biochemical and structural studies.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SQOR | Sulfide:quinone oxidoreductase; oxidizes hydrogen sulfide | Mitochondrial sulfide detoxification; structure and mechanism |
| ERV1/GFER | Sulfhydryl oxidase; catalyzes disulfide bond formation in mitochondria | Protein import and folding; MIA pathway [1,6] |
| SUOX | Sulfite oxidase; oxidizes sulfite to sulfate | Sulfur metabolism; molybdenum cofactor enzyme |
| QSOX1 | Quiescin sulfhydryl oxidase; oxidizes thiols in secreted proteins | Extracellular matrix remodeling; cancer |
| ETHE1 | Persulfide dioxygenase; sulfur dioxygenase | Mitochondrial sulfur metabolism; ethylmalonic encephalopathy |
| MPST | Mercaptopyruvate sulfurtransferase; produces hydrogen sulfide | Cysteine catabolism; sulfide signaling |
| CBS | Cystathionine beta-synthase; produces hydrogen sulfide | Transsulfuration; redox regulation |
| CTH | Cystathionine gamma-lyase; produces hydrogen sulfide | Hydrogen sulfide biosynthesis |
| SQR | Sulfide:quinone oxidoreductase (bacterial) | Bacterial sulfur respiration; pathogenicity |
| SOX | Sulfite oxidase (plant) | Plant sulfur metabolism; photorespiration |
| ALR | Augmenter of liver regeneration; sulfhydryl oxidase | Liver regeneration; mitochondrial function |
| PDI | Protein disulfide isomerase; thiol oxidase | Endoplasmic reticulum folding |
| ERO1 | Endoplasmic reticulum oxidoreductin; sulfhydryl oxidase | Oxidative protein folding |
| BCOA | Benzoyl-CoA reductase; tungsten-containing | Anaerobic aromatic metabolism |
| TST | Thiosulfate sulfurtransferase; sulfur transfer | Cyanide detoxification; sulfur metabolism |
| SOD | Superoxide dismutase; not direct but related redox | Antioxidant defense |
How Is oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor Regulated?
The activity of GO:0016670 enzymes is regulated at multiple levels. Transcriptional regulation responds to oxygen availability and sulfur source, as seen in Salmonella enterica where respiratory pathways for sulfur reduction are induced under anaerobic conditions. Post-translational modifications, such as disulfide bond formation in Erv1, control catalytic activity and protein interactions. The mitochondrial import and assembly (MIA) pathway regulates Erv1 levels and oxidative folding capacity. Additionally, cellular redox state, including glutathione and NADPH levels, modulates enzyme activity through thiol-disulfide exchange. In mammalian cells, hypoxia-inducible factors (HIFs) can influence the expression of sulfur oxidoreductases under low oxygen.
oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SQOR | Neurodegeneration, sulfide toxicity | Knockout mice, neuronal cell lines |
| ETHE1 | Ethylmalonic encephalopathy | Patient fibroblasts, Ethe1-/- mice |
| ERV1/GFER | Mitochondrial myopathy, encephalopathy | Knockout cell lines, patient iPSCs |
| QSOX1 | Cancer progression, metastasis | Xenograft models, CRISPR KO in cancer cells |
| SUOX | Sulfite oxidase deficiency | Patient-derived fibroblasts, Suox-/- mice |
Neurodegenerative Diseases
Impaired hydrogen sulfide oxidation by SQOR leads to sulfide accumulation, which can inhibit cytochrome c oxidase and contribute to neurodegeneration. Studies have linked SQOR dysfunction to Alzheimer's and Parkinson's diseases, where oxidative stress and mitochondrial dysfunction are hallmarks. Erv1/ALR mutations cause progressive mitochondrial myopathy and encephalopathy, highlighting the importance of sulfhydryl oxidases in neuronal survival.
Cancer
Altered expression of sulfhydryl oxidases such as QSOX1 and Erv1 has been observed in various cancers. QSOX1 promotes tumor cell proliferation and invasion by remodeling the extracellular matrix. Erv1 supports cancer cell survival under oxidative stress by maintaining mitochondrial integrity. Targeting these enzymes may offer therapeutic strategies.
Mitochondrial Disorders
Mutations in ETHE1, a sulfur dioxygenase, cause ethylmalonic encephalopathy, a severe mitochondrial disorder characterized by sulfide accumulation and vascular lesions. Defects in the MIA pathway components, including Erv1, result in mitochondrial protein import defects and multi-systemic disease.
From oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Catalytic mechanism of SQOR | Point mutations in active site residues (e.g., FAD-binding) |
| Role of Erv1 in mitochondrial import | Knockout and rescue with tagged Erv1 |
| Sulfide detoxification in vivo | Sqor knockout mice |
| QSOX1 role in cancer | Overexpression and knockout in cancer cell lines |
| Sulfite oxidase deficiency | Suox knock-in of patient mutations |
| Bacterial sulfur respiration | Salmonella enterica deletion mutants |
How to Study the oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Stopped-flow kinetics | Electron transfer rates, substrate turnover | Mechanistic studies of SQOR, Erv1 [1,3] |
| X-ray crystallography | 3D structure of enzyme-cofactor complexes | Active site mapping [3,4] |
| EPR spectroscopy | Paramagnetic intermediates, flavin radicals | Redox state analysis |
| CRISPR knockout | Loss-of-function phenotypes | Gene function in cells and mice [3,6] |
| RNA-seq | Transcriptional changes | Pathway regulation |
| Proteomics | Protein expression and modifications | Disulfide bond formation |
| CRISPR library screening | Genetic interactions, fitness genes | Target discovery |
| Metabolomics | Sulfur metabolite levels | Sulfide/sulfite quantification |
Enzyme Kinetics and Spectroscopy
Kinetic characterization using stopped-flow spectrophotometry and electron paramagnetic resonance (EPR) can measure electron transfer rates and identify reaction intermediates. For example, Erv1 kinetics revealed a ping-pong mechanism with cytochrome c as an electron acceptor. Sulfite oxidase mechanism has been dissected using rapid-reaction kinetics and site-directed mutagenesis.
Structural Biology
X-ray crystallography and cryo-electron microscopy provide atomic-level insights into active site architecture and cofactor coordination. The structure of human SQOR revealed a unique FAD-binding fold and a quinone-binding site. Structural studies of sulfhydryl oxidases have elucidated the disulfide relay mechanism [1,7].
Cellular and Animal Models
CRISPR-Cas9 knockout and knock-in cell lines, as well as transgenic mice, are used to study physiological roles. For instance, Sqor knockout mice accumulate sulfide and develop metabolic abnormalities. Erv1 conditional knockouts in mice show mitochondrial dysfunction.
Omics and Screening
RNA-seq and proteomics can identify transcriptional and post-translational changes upon enzyme perturbation. CRISPR library screening can uncover synthetic lethal interactions and modifiers of sulfur oxidation pathways.
How CRISPR Can Be Used to Study GO:0016670 oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor
Knockout
CRISPR-Cas9 knockout of genes encoding GO:0016670 enzymes (e.g., SQOR, ERV1) allows researchers to assess loss-of-function phenotypes, such as sulfide accumulation, mitochondrial dysfunction, and altered stress responses [3,6]. Knockout cell lines are valuable for drug sensitivity screens and metabolic profiling.
Point Mutation
Introducing specific point mutations (e.g., in catalytic residues or cofactor-binding sites) via CRISPR base editing or homology-directed repair can dissect enzyme mechanism without completely abolishing protein expression. For example, mutating the FAD-binding residue in SQOR clarifies its role in electron transfer.
Knock-in
Knock-in of tagged versions (e.g., FLAG, GFP) or disease-associated mutations enables localization, interaction, and functional studies. Tagged Erv1 knock-in cells facilitate affinity purification and live-cell imaging. Patient mutations in SUOX can be knocked into cell lines to model sulfite oxidase deficiency.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of GO:0016670 genes can probe gain-of-function effects, such as increased sulfide detoxification or enhanced protein folding capacity. Overexpression of QSOX1 in cancer cells promotes proliferation and invasion.
How EDITGENE Supports oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor Research
Researchers studying oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor-related genes often need to determine whether a candidate gene is causally involved in a specific pathway or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models, enabling functional validation and mechanistic dissection.
Contact EDITGENE today to design your custom CRISPR model for oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor research.
Frequently Asked Questions About oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor
What is GO:0016670?
GO:0016670 is a Gene Ontology molecular function term for oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor. It describes enzymes that oxidize sulfur-containing groups using oxygen as the electron acceptor [1,3,4].
What genes are involved in oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor?
Key genes include SQOR, ERV1/GFER, SUOX, QSOX1, ETHE1, and bacterial SQR. These encode enzymes such as sulfide:quinone oxidoreductase, sulfhydryl oxidases, and sulfite oxidase [1,3,4,8].
What diseases are associated with GO:0016670?
Dysfunction is linked to neurodegenerative diseases, mitochondrial disorders like ethylmalonic encephalopathy, and cancer. For example, SQOR deficiency leads to sulfide accumulation and neurotoxicity [3,6].
How can I study oxidoreductase activity, acting on a sulfur group of donors, oxygen as acceptor?
Common methods include enzyme kinetics, X-ray crystallography, CRISPR knockout/knock-in cell models, and omics approaches. EDITGENE offers custom CRISPR services for these studies [1,3,4].
What is the role of sulfide:quinone oxidoreductase (SQOR)?
SQOR catalyzes the oxidation of hydrogen sulfide to sulfane sulfur, protecting mitochondria from sulfide toxicity. Its structure and mechanism have been elucidated.
What are sulfhydryl oxidases?
Sulfhydryl oxidases are enzymes that oxidize thiol groups to disulfides, often coupled to oxygen reduction. Examples include Erv1 and QSOX1, involved in protein folding [1,7,8].
How is GO:0016670 regulated?
Regulation occurs at transcriptional, post-translational, and redox levels. Oxygen availability, sulfide levels, and the MIA pathway influence enzyme activity [1,5,6].
What model systems are used to study GO:0016670?
Model systems include knockout mice, patient-derived fibroblasts, bacterial mutants, and CRISPR-engineered cell lines. Each offers unique advantages for mechanistic and disease research [3,5,6].
Can CRISPR be used to study GO:0016670?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression are powerful tools to dissect gene function and model diseases related to sulfur oxidoreductases [3,6].
What services does EDITGENE provide for GO:0016670 research?
EDITGENE offers custom CRISPR knockout, point mutation, knock-in, overexpression cell models, CRISPR library screening, and bioinformatics analysis tailored to sulfur oxidoreductase genes.
Conclusion
GO:0016670 represents a vital class of enzymes that couple sulfur oxidation to oxygen reduction, impacting mitochondrial function, protein folding, and human health. Advances in structural biology and CRISPR-based models continue to unravel their mechanisms and disease relevance. EDITGENE's comprehensive services empower researchers to generate precise cell models and accelerate discoveries in this field.
References
- 1. Tang X et al.. 2020. Kinetic characterisation of Erv1, a key component for protein import and folding in yeast mitochondria.. FEBS J 287(6):1220-1231 PMID: 31569302
- 2. Kung JW et al.. 2009. Identification and characterization of the tungsten-containing class of benzoyl-coenzyme A reductases.. Proc Natl Acad Sci U S A 106(42):17687-92 PMID: 19815533
- 3. Jackson MR et al.. 2019. X-Ray Structure of Human Sulfide:Quinone Oxidoreductase: Insights into the Mechanism of Mitochondrial Hydrogen Sulfide Oxidation.. Structure 27(5):794-805.e4 PMID: 30905673
- 4. Johnson-Winters K et al.. 2010. Elucidating the catalytic mechanism of sulfite oxidizing enzymes using structural, spectroscopic, and kinetic analyses.. Biochemistry 49(34):7242-54 PMID: 20666399
- 5. Hinsley AP et al.. 2002. Specificity of respiratory pathways involved in the reduction of sulfur compounds by Salmonella enterica.. Microbiology (Reading) 148(Pt 11):3631-3638 PMID: 12427953
- 6. Mordas A et al.. 2015. The MIA pathway: a key regulator of mitochondrial oxidative protein folding and biogenesis.. Acc Chem Res 48(8):2191-9 PMID: 26214018
- 7. Swaisgood HE et al.. 1979. Sulphydryl oxidase: oxidation of sulphydryl groups and the formation of three-dimensional structure in proteins.. Ciba Found Symp PMID: 398763
- 8. Faccio G et al.. 2011. Sulfhydryl oxidases: sources, properties, production and applications.. Appl Microbiol Biotechnol 91(4):957-66 PMID: 21732243
