GO:0016649 oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0016649 describes a molecular function: oxidation-reduction reactions in which a CH-NH group donates electrons and a quinone or similar compound acts as the electron acceptor.
• This activity is characteristic of quinoproteins, a class of enzymes that use quinone cofactors such as pyrroloquinoline quinone (PQQ) or tryptophan tryptophylquinone (TTQ) to catalyze redox reactions.
• The CH-NH group donor is typically an amine or amino acid, and the quinone acceptor can be ubiquinone, menaquinone, or a synthetic quinone.
• These enzymes are involved in bacterial energy metabolism, amine oxidation, and detoxification, and some have biotechnological applications in biosensors and biocatalysis.
• Aryl-alcohol flavoxidases can act as quinone reductases, expanding the physiological roles of this enzyme class.
• Studying GO:0016649 requires integrating enzymology, structural biology, and CRISPR-based gene editing to dissect gene function and disease relevance [1,6].
Description
GO:0016649, oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor, is a molecular function term in the Gene Ontology that defines a specific type of redox reaction. In these reactions, a CH-NH group (typically an amine or amino acid) serves as the electron donor, and a quinone or a structurally similar compound acts as the electron acceptor. This activity is a hallmark of quinoproteins, a diverse family of enzymes that utilize quinone cofactors to catalyze oxidation-reduction reactions. Understanding this term is crucial for researchers studying bacterial metabolism, amine oxidation, and the development of biocatalysts and biosensors. The term is also relevant to biotechnology, as enzymes with this activity can be engineered for industrial applications. This article provides a comprehensive overview of GO:0016649, covering its definition, mechanism, key genes, disease associations, and research methods, with a focus on how CRISPR gene editing can be used to study these enzymes.
oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor At A Glance
| GO ID | GO:0016649 |
|---|---|
| GO term | oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor |
| Ontology | molecular_function |
| Synonym | None |
| Major function | Catalyzes redox reactions with CH-NH donors and quinone acceptors |
| EC number | 1.4.99.- (acting on the CH-NH group of donors, quinone or similar compound as acceptor) |
| Cofactors | Quinone cofactors such as PQQ, TTQ, or topaquinone |
| Example enzymes | Quinoprotein amine dehydrogenases, methylamine dehydrogenase |
| Related terms | GO:0016648 (oxidoreductase activity, acting on the CH-NH group of donors, disulfide as acceptor) |
What Is GO:0016649?
GO:0016649 is defined as the catalysis of an oxidation-reduction (redox) reaction in which a CH-NH group acts as a hydrogen or electron donor and reduces a quinone or similar compound. In simpler terms, it is a chemical reaction where an amine-containing molecule gives up electrons, and a quinone molecule accepts them. This activity is typically found in enzymes that contain quinone cofactors, such as PQQ or TTQ, and is involved in various biological processes, including energy production and detoxification.
Why Is oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor Important in Cell Biology?
GO:0016649 is important because it represents a fundamental redox mechanism used by a wide range of organisms, particularly bacteria, to derive energy from amines and other CH-NH containing compounds. These enzymes are also involved in the metabolism of neurotransmitters and xenobiotics, and their dysfunction has been linked to various diseases. Furthermore, quinoproteins are attractive targets for biotechnology, as they can be used in biosensors for glucose and other analytes, and in biocatalysis for the production of fine chemicals. Understanding the molecular details of this activity can aid in the design of inhibitors and the engineering of novel enzymes.
• Quinoproteins catalyze key steps in bacterial energy metabolism, such as the oxidation of methanol and methylamine.
• They are involved in the degradation of amines, including biogenic amines and environmental pollutants.
• Some quinoproteins are implicated in human diseases, such as tyrosinemia and certain neurological disorders.
• The activity is essential for the function of copper amine oxidases, which regulate neurotransmitter levels.
• Quinone reductases with this activity can protect cells from oxidative stress by reducing quinones.
• Enzymes with this activity are used in biosensors for glucose, lactate, and other metabolites.
• They are potential targets for antibiotics, as they are essential in some pathogenic bacteria.
• Understanding this activity can aid in the development of biocatalysts for industrial applications.
• CRISPR-based editing of genes encoding these enzymes can reveal their physiological roles.
• This GO term helps in the functional annotation of genomes and metagenomes.
Mechanism, Genes and Research Methods
What Happens During oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor?
In simple terms: In simple terms, an enzyme with this activity takes electrons from an amine-containing molecule and gives them to a quinone molecule.
The reaction catalyzed by enzymes with GO:0016649 involves the oxidation of a CH-NH group, which is typically an amine or an amino acid, and the reduction of a quinone or similar compound. The CH-NH group loses electrons (and often a proton), becoming oxidized, while the quinone gains electrons, becoming reduced to a hydroquinone. This redox reaction is often coupled to the respiratory chain or other electron transfer pathways. The enzymes that catalyze this reaction are called quinoproteins and contain specialized quinone cofactors, such as pyrroloquinoline quinone (PQQ) or tryptophan tryptophylquinone (TTQ), which participate directly in the electron transfer.
Substrate Specificity and Donor Diversity
In simple terms: Different enzymes can use different amines as donors, but they all use quinones as acceptors.
The CH-NH group donors can vary widely, including primary amines, amino acids, and methylamine. For example, methylamine dehydrogenase oxidizes methylamine, while copper amine oxidases oxidize primary amines. The quinone acceptor is typically ubiquinone or menaquinone in vivo, but artificial electron acceptors such as dichlorophenolindophenol (DCPIP) or ferricyanide can be used in vitro. The specificity for the donor and acceptor depends on the enzyme's active site structure and the nature of the quinone cofactor.
Structure and Composition of oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor
In simple terms: These enzymes are proteins that contain a special quinone molecule to help them transfer electrons.
Quinoproteins are composed of one or more polypeptide chains that fold to create an active site where the quinone cofactor is bound. The cofactor can be PQQ, TTQ, topaquinone (TPQ), or lysine tyrosylquinone (LTQ), depending on the enzyme. For example, methylamine dehydrogenase is a TTQ-containing enzyme, while copper amine oxidases contain TPQ. The protein scaffold provides the appropriate environment for the cofactor to function and for substrate binding. Some quinoproteins also contain metal ions, such as calcium or copper, which are essential for activity.
Molecular Mechanism of oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor
In simple terms: The enzyme uses its quinone cofactor to pull electrons from the donor and pass them to the acceptor.
The catalytic mechanism typically involves the quinone cofactor accepting electrons from the CH-NH donor, forming a reduced hydroquinone intermediate. This is often accompanied by the release of ammonia or an amine. The electrons are then transferred to the external electron acceptor, such as a quinone or cytochrome. In some enzymes, the reaction proceeds through a ping-pong mechanism, where the donor binds first, reduces the cofactor, and then the acceptor binds and oxidizes the cofactor. The detailed mechanism varies among different quinoproteins but always involves the redox cycling of the quinone cofactor.
Cofactors and Regulation
In simple terms: The activity depends on special quinone cofactors and can be regulated by the availability of these cofactors and the enzyme's expression.
The quinone cofactors are essential for activity and are often synthesized through complex biosynthetic pathways. For example, PQQ is synthesized from tyrosine and glutamate in bacteria. The activity can be regulated at the level of gene expression, cofactor biosynthesis, and post-translational modifications. Some quinoproteins are also regulated by calcium or other metal ions. Additionally, the redox state of the quinone pool in the membrane can influence the activity.
Key Genes Involved in GO:0016649 oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor
The following genes encode enzymes or proteins associated with GO:0016649, including quinoproteins and related redox enzymes.
| Gene | Major Role | Research Relevance |
|---|---|---|
| mauA | Methylamine dehydrogenase small subunit | Model enzyme for TTQ biosynthesis and quinoprotein mechanism |
| mauB | Methylamine dehydrogenase large subunit | Contains TTQ cofactor; studied for electron transfer |
| mauC | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauD | Methylamine dehydrogenase accessory protein | Required for TTQ formation |
| mauE | Methylamine dehydrogenase accessory protein | May be involved in cofactor insertion |
| mauF | Methylamine dehydrogenase accessory protein | Function in TTQ biosynthesis |
| mauG | Methylamine dehydrogenase accessory protein | Catalyzes TTQ biosynthesis |
| mauL | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauM | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauN | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauO | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauP | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauQ | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauR | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauS | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauT | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauU | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
| mauV | Methylamine dehydrogenase accessory protein | Involved in TTQ biosynthesis |
How Is oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor Regulated?
The activity of enzymes with GO:0016649 is regulated at multiple levels. Gene expression of quinoproteins is often controlled by environmental factors such as the availability of amines or oxygen. The biosynthesis of quinone cofactors, such as PQQ and TTQ, is tightly regulated and requires specific enzymes. Additionally, the activity can be modulated by post-translational modifications, metal ion binding, and the redox state of the cell. In some cases, the enzyme activity is regulated by the availability of the electron acceptor, such as quinones in the membrane.
oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| Copper amine oxidase (e.g., AOC3) | Inflammation, diabetes | Knockout mice, cell lines |
| Quinone reductase (e.g., NQO1) | Cancer, oxidative stress | CRISPR knockout in cancer cell lines |
| Methylamine dehydrogenase (mau genes) | Bacterial metabolism | Bacterial knockout mutants |
| Aryl-alcohol flavoxidase | Fungal metabolism, biocatalysis | Overexpression in fungi |
| PQQ-dependent dehydrogenases | Metabolic disorders | Knock-in mouse models |
Quinoproteins in Human Health and Disease
Quinoproteins are not only found in bacteria but also in humans, where they play roles in neurotransmitter metabolism and oxidative stress responses. For example, copper amine oxidases, which contain TPQ, are involved in the breakdown of biogenic amines such as histamine and dopamine. Dysregulation of these enzymes has been linked to inflammatory diseases and neurological disorders. Additionally, quinone reductases can protect against oxidative stress by reducing quinones, and their dysfunction may contribute to cancer and neurodegeneration.
Role in Bacterial Pathogenesis
Many pathogenic bacteria rely on quinoproteins for energy metabolism and survival within the host. For instance, methylamine dehydrogenase allows bacteria to utilize methylamine as a carbon source. Inhibitors of these enzymes could serve as novel antibiotics. Understanding the structure and mechanism of these enzymes is therefore important for drug development.
Biotechnological and Industrial Applications
Enzymes with GO:0016649 activity are used in biosensors for the detection of glucose, lactate, and other metabolites. They are also employed in biocatalysis for the production of chiral amines and other fine chemicals. Engineering these enzymes for improved stability and substrate specificity is an active area of research.
From oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of a specific quinoprotein in bacterial growth? | Knockout of the gene in bacteria (e.g., mauA) |
| How does a point mutation affect enzyme activity? | Point mutation knock-in in cell lines |
| What is the subcellular localization of the enzyme? | Tagged knock-in with fluorescent protein |
| Can overexpression increase metabolite production? | Overexpression in host cells |
| What are the off-target effects of a drug targeting the enzyme? | CRISPR library screening |
| How does the enzyme contribute to disease? | Knockout mouse models |
How to Study the oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Spectrophotometric assay | Enzyme activity | Kinetic characterization |
| X-ray crystallography | 3D structure | Mechanism and drug design |
| CRISPR knockout | Gene function | Phenotypic analysis |
| RNA-seq | Gene expression | Transcriptional regulation |
| Proteomics | Protein abundance | Expression profiling |
| Site-directed mutagenesis | Residue function | Mechanistic studies |
| Isothermal titration calorimetry | Binding affinity | Substrate/cofactor binding |
Enzymatic Assays
Enzymatic activity of GO:0016649 can be measured using spectrophotometric assays that monitor the reduction of artificial electron acceptors such as DCPIP or ferricyanide. These assays are typically performed with purified enzyme or cell lysates and can be used to determine kinetic parameters and substrate specificity.
Structural Biology
X-ray crystallography and cryo-electron microscopy can reveal the three-dimensional structure of quinoproteins, including the binding of the quinone cofactor and substrate. These methods are essential for understanding the catalytic mechanism and for structure-based drug design.
Genetic and Genomic Approaches
CRISPR-Cas9 gene editing can be used to create knockout or knock-in mutations in genes encoding quinoproteins. This allows researchers to study the physiological roles of these enzymes in various organisms. Additionally, RNA-seq and proteomics can be used to analyze the expression of these genes under different conditions.
Bioinformatics and Comparative Genomics
Bioinformatic tools can identify genes encoding quinoproteins in sequenced genomes and metagenomes. Sequence analysis can reveal conserved motifs and evolutionary relationships, helping to predict function and guide experimental design.
How CRISPR Can Be Used to Study GO:0016649 oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor
Knockout
CRISPR knockout of genes encoding quinoproteins can abolish enzyme activity and reveal their physiological roles. For example, knocking out mauA in methylotrophic bacteria prevents growth on methylamine. Knockout cell lines can be used to study the contribution of these enzymes to disease.
Point Mutation
Point mutations can be introduced to study the role of specific amino acid residues in catalysis or cofactor binding. For instance, mutating the active site cysteine of a quinoprotein can inactivate the enzyme, confirming its catalytic role.
Knock-in
Knock-in of a tagged version of the gene (e.g., GFP or FLAG) allows for localization and interaction studies. This can be achieved using CRISPR-mediated homology-directed repair.
Overexpression
Overexpression of a quinoprotein can be used to produce large amounts of enzyme for structural or biochemical studies, or to enhance metabolic pathways in biotechnology.
How EDITGENE Supports oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor Research
Researchers studying oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor-related genes often need to determine whether a candidate gene is causally involved in a specific biological process or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to facilitate this research, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor research.
Frequently Asked Questions About oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor
What is GO:0016649?
GO:0016649 is a Gene Ontology molecular function term that describes oxidoreductase activity where a CH-NH group donates electrons and a quinone or similar compound acts as the electron acceptor.
What enzymes have oxidoreductase activity, acting on the CH-NH group of donors, quinone or similar compound as acceptor?
Enzymes with this activity include quinoproteins such as methylamine dehydrogenase, copper amine oxidases, and PQQ-dependent dehydrogenases.
What genes are involved in GO:0016649?
Genes encoding quinoproteins, such as mauA, mauB, and other mau genes in methylotrophic bacteria, as well as human genes like AOC3 and NQO1, are associated with this activity [1,6].
How is GO:0016649 regulated?
It is regulated by gene expression, cofactor biosynthesis, metal ions, and the redox state of the cell.
What diseases are associated with GO:0016649?
Dysregulation of quinoproteins has been linked to inflammatory diseases, neurological disorders, and cancer [1,6].
What are the research methods for studying GO:0016649?
Methods include enzymatic assays, X-ray crystallography, CRISPR gene editing, RNA-seq, and proteomics.
Can CRISPR be used to study GO:0016649?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models can be used to study the function of genes encoding these enzymes.
What are quinoproteins?
Quinoproteins are enzymes that contain a quinone cofactor, such as PQQ or TTQ, and catalyze redox reactions.
What is the role of quinones in this activity?
Quinones act as electron acceptors, being reduced to hydroquinones during the reaction.
How can EDITGENE help with GO:0016649 research?
EDITGENE provides CRISPR knockout, point mutation, knock-in, overexpression, library screening, and bioinformatics services to study genes related to this activity.
Conclusion
GO:0016649 represents a vital molecular function that underpins diverse biological processes, from bacterial energy metabolism to human neurotransmitter regulation. Understanding the enzymes that catalyze these reactions, their mechanisms, and their roles in disease can lead to new therapeutic and biotechnological applications. CRISPR-based gene editing offers powerful tools to dissect these functions, and EDITGENE is ready to support your research with tailored services.
References
- 1. Anthony C. 1996. Quinoprotein-catalysed reactions.. Biochem J 320 ( Pt 3)(Pt 3):697-711 PMID: 9003352
- 6. Ferreira P et al.. 2023. Expanding the Physiological Role of Aryl-Alcohol Flavooxidases as Quinone Reductases.. Appl Environ Microbiol 89(5):e0184422 PMID: 37154753
