GO:0008817 corrinoid adenosyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0008817 (corrinoid adenosyltransferase activity) catalyzes the ATP-dependent reductive adenosylation of corrinoids such as cob(II)alamin to form adenosylcobalamin (AdoCbl), a cofactor required by B12-dependent enzymes.
• The reaction consumes two ATP and two corrinoid molecules per turnover, producing two adenosylcorrinoids, two triphosphates, and oxidized electron-transfer flavoprotein.
• Key enzymes include human MMAB (also known as ATP:cob(I)alamin adenosyltransferase), bacterial PduO, EutT, and CobA, which differ in metal dependence and oxygen sensitivity [2,5,8].
• Deficiency of MMAB causes methylmalonic acidemia (MMA), an inherited disorder of propionate metabolism with severe neurological and metabolic consequences.
• PduO from Lactobacillus reuteri is a model enzyme for studying the four-coordinate Co(II) corrinoid intermediate and the role of specific residues such as Phe112 in catalysis [2,7].
• Studying GO:0008817 helps researchers understand B12 cofactor biosynthesis, bacterial metabolic engineering, and human disease mechanisms linked to cobalamin metabolism [3,6].
Description
Corrinoid adenosyltransferase activity (GO:0008817) is a molecular function that enables the ATP-dependent conversion of corrinoid substrates, such as cob(II)alamin, into adenosylcorrinoids, most notably adenosylcobalamin (AdoCbl). AdoCbl is an essential cofactor for B12-dependent enzymes, including methylmalonyl-CoA mutase and certain class II ribonucleotide reductases, and its synthesis is therefore critical for both prokaryotic and eukaryotic metabolism [3,6]. The reaction is unusual because it requires a reductive step to generate a highly reactive cob(I)alamin intermediate before adenosylation can occur. This function is encoded by a small family of enzymes, including human MMAB and bacterial PduO, EutT, and CobA, which share a common catalytic strategy but differ in metal content, substrate specificity, and oxygen sensitivity [2,5,8]. Because defects in corrinoid adenosyltransferase activity lead to methylmalonic acidemia and related metabolic disorders, the enzyme is a target for both clinical diagnostics and metabolic engineering [1,6].
corrinoid adenosyltransferase activity At A Glance
| GO ID | GO:0008817 |
|---|---|
| GO term | corrinoid adenosyltransferase activity |
| Ontology | molecular_function |
| Synonym | ATP:corrinoid adenosyltransferase activity; cob(I)alamin adenosyltransferase activity; aquacob(I)alamin adenosyltransferase activity; vitamin B12s adenosyltransferase activity |
| Major function | Catalyzes the ATP-dependent reductive adenosylation of corrinoids to form adenosylcobalamin |
| Reaction | 2 ATP + 2 corrinoid + reduced [electron-transfer flavoprotein] = 2 adenosylcorrinoid + 3 H+ + oxidized [electron-transfer flavoprotein] + 2 triphosphate |
| Substrates | ATP, corrinoid (e.g., cob(II)alamin, cob(II)inamide, cob(II)yrinate a,c diamide), reduced electron-transfer flavoprotein |
| Products | Adenosylcorrinoid, triphosphate, oxidized electron-transfer flavoprotein, H+ |
| Enzyme family | ATP:corrinoid adenosyltransferases (e.g., MMAB, PduO, EutT, CobA) |
What Is GO:0008817?
According to the Gene Ontology, GO:0008817 (corrinoid adenosyltransferase activity) is defined as the catalysis of the reaction: 2 ATP + 2 corrinoid + reduced [electron-transfer flavoprotein] = 2 adenosylcorrinoid + 3 H+ + oxidized [electron-transfer flavoprotein] + 2 triphosphate. The corrinoid substrate can be cob(II)yrinate a,c diamide, cob(II)inamide, or cob(II)alamin. In simpler terms, this activity uses ATP and a reducing agent to attach an adenosyl group to a corrinoid molecule, producing the active cofactor form adenosylcobalamin.
Why Is corrinoid adenosyltransferase activity Important in Cell Biology?
Corrinoid adenosyltransferase activity is essential for the biosynthesis of adenosylcobalamin, a cofactor required by methylmalonyl-CoA mutase and other B12-dependent enzymes [3,6]. In humans, loss-of-function mutations in the MMAB gene cause methylmalonic acidemia, a life-threatening disorder characterized by accumulation of methylmalonic acid and neurological damage. In bacteria, this activity supports diverse metabolic pathways, including 1,2-propanediol degradation and ethanolamine utilization, making it relevant for microbiome function and metabolic engineering [5,8]. Understanding the catalytic mechanism, substrate specificity, and regulation of these enzymes can inform therapeutic strategies for cobalamin-related disorders and the design of microbial cell factories [2,7].
• Provides adenosylcobalamin for methylmalonyl-CoA mutase, a key enzyme in propionate metabolism.
• Defects in human MMAB cause methylmalonic acidemia, an inherited metabolic disease.
• Supports bacterial metabolic pathways such as 1,2-propanediol and ethanolamine utilization [5,8].
• Enables the study of reductive adenosylation chemistry and radical-based catalysis [2,5].
• Serves as a target for metabolic engineering of B12-dependent biotransformations.
• Contributes to understanding of cobalamin trafficking and cofactor homeostasis.
• Offers a model system for investigating metal-dependent enzyme mechanisms.
• Facilitates development of diagnostics for cobalamin disorders.
Molecular Mechanism of corrinoid adenosyltransferase activity
Substrate binding and reduction of Co(II) corrinoid
In simple terms: The enzyme first grabs the corrinoid molecule and reduces its cobalt ion to a reactive state.
Corrinoid adenosyltransferases bind a Co(II) corrinoid substrate, such as cob(II)alamin, and facilitate its reduction to a highly reactive Co(I) species. In the PduO enzyme from Lactobacillus reuteri, residue Phe112 is critical for forming the four-coordinate Co(II) corrinoid substrate and for catalytic activity. Spectroscopic studies have shown that the enzyme interacts directly with the corrinoid to modulate its electronic structure.
ATP-dependent adenosylation
In simple terms: Using ATP, the enzyme transfers an adenosyl group onto the reduced corrinoid to make the active cofactor.
Following reduction, the enzyme catalyzes the transfer of an adenosyl group from ATP to the Co(I) corrinoid, yielding adenosylcobalamin and triphosphate. Kinetic studies of PduO from L. reuteri revealed that the enzyme has specificity for ATP and that the reaction proceeds through a ternary complex. The overall reaction consumes two ATP molecules per two corrinoid molecules, consistent with the GO definition.
Electron transfer and flavoprotein coupling
In simple terms: The enzyme uses a reduced electron-transfer flavoprotein to supply electrons for the reduction step.
The reductive step requires electrons, which are provided by reduced electron-transfer flavoprotein (ETF). The GO definition specifies that reduced ETF is oxidized during the reaction, linking corrinoid adenosylation to cellular redox metabolism. This coupling ensures that the highly reactive Co(I) intermediate is generated only when reducing equivalents are available.
Metal dependence and oxygen sensitivity
In simple terms: Some versions of the enzyme need metals and are sensitive to oxygen, which affects how they work.
The EutT enzyme from Salmonella enterica is an oxygen-labile, metal-containing ATP:corrinoid adenosyltransferase, distinguishing it from other family members. In contrast, PduO from L. reuteri does not require a metal cofactor for activity but still relies on specific residues for substrate positioning. These differences highlight the mechanistic diversity within the enzyme family.
Product release and cofactor delivery
In simple terms: After making adenosylcobalamin, the enzyme releases it so it can be used by other proteins.
Once adenosylcobalamin is formed, it is released from the enzyme and delivered to target B12-dependent enzymes, such as methylmalonyl-CoA mutase. In humans, MMAB is thought to channel AdoCbl to methylmalonyl-CoA mutase, although the exact trafficking mechanism remains an active area of research.
Key Genes Involved in GO:0008817 corrinoid adenosyltransferase activity
The following genes encode enzymes with corrinoid adenosyltransferase activity or are directly involved in the pathway.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MMAB (human) | ATP:cob(I)alamin adenosyltransferase; synthesizes AdoCbl for methylmalonyl-CoA mutase | Mutations cause methylmalonic acidemia; target for metabolic disease research |
| PduO (Lactobacillus reuteri) | ATP:corrinoid adenosyltransferase; model enzyme for mechanism | Key model for studying Co(II) reduction and substrate specificity [2,5] |
| EutT (Salmonella enterica) | Oxygen-labile, metal-containing ATP:corrinoid adenosyltransferase | Model for metal-dependent catalysis and anaerobic metabolism |
| CobA (bacteria) | ATP:cob(I)alamin adenosyltransferase in cobalamin biosynthesis | Studied for B12 biosynthesis and metabolic engineering |
| MCM (human) | Methylmalonyl-CoA mutase; uses AdoCbl as cofactor | Downstream enzyme; relevant to methylmalonic acidemia |
| MTR (human) | Methionine synthase; uses methylcobalamin | Related B12 enzyme; interconversion with AdoCbl studied |
| PduCDE (bacteria) | 1,2-propanediol degradation; requires AdoCbl | Pathway context for PduO function |
| EutBC (bacteria) | Ethanolamine utilization; requires AdoCbl | Pathway context for EutT function |
| MMAA (human) | GTPase involved in AdoCbl trafficking to MCM | Interacts with MMAB; disease relevance |
| MMUT (human) | Methylmalonyl-CoA mutase gene | Mutations cause methylmalonic acidemia |
| CblA (bacteria) | Cobalamin biosynthesis protein | Related to adenosylation steps |
| CblB (bacteria) | Cobalamin biosynthesis protein | Related to adenosylation steps |
| PduO homologs | Corrinoid adenosyltransferase in various bacteria | Comparative enzymology |
| EutT homologs | Corrinoid adenosyltransferase in various bacteria | Comparative enzymology |
| MMAB variants | Disease-associated mutations | Genotype-phenotype studies |
| ATP:cob(I)alamin adenosyltransferase | Enzyme activity | Biochemical assays |
How Is corrinoid adenosyltransferase activity Regulated?
The expression and activity of corrinoid adenosyltransferases are regulated in response to cobalamin availability and cellular redox status. In bacteria, genes such as pduO and eutT are often part of operons that are induced by specific substrates (e.g., 1,2-propanediol or ethanolamine) and regulated by global regulators [5,8]. In humans, MMAB expression may be influenced by B12 status, but detailed transcriptional regulation remains incompletely understood. The enzyme's activity depends on the availability of reduced electron-transfer flavoprotein, linking it to cellular energy metabolism.
corrinoid adenosyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| MMAB | Methylmalonic acidemia | MMAB knockout human cell lines (e.g., HEK293, HepG2) |
| MMUT | Methylmalonic acidemia | MMUT point-mutation knock-in mice |
| PduO | Bacterial metabolic pathway | Lactobacillus reuteri pduO deletion |
| EutT | Salmonella colonization | Salmonella enterica eutT mutant |
| MTR | Homocystinuria | MTR knockout cell models |
Methylmalonic acidemia (MMA)
Biallelic mutations in MMAB cause methylmalonic acidemia, an inherited disorder of propionate metabolism characterized by accumulation of methylmalonic acid, metabolic acidosis, and neurological impairment. The disease results from deficient synthesis of adenosylcobalamin, leading to impaired methylmalonyl-CoA mutase activity.
Cobalamin metabolism disorders
Defects in corrinoid adenosyltransferase activity can lead to combined methylmalonic acidemia and homocystinuria, depending on the specific enzyme affected. These disorders highlight the importance of AdoCbl synthesis for both methylmalonyl-CoA mutase and methionine synthase pathways.
Bacterial pathogenesis and microbiome
In pathogens such as Salmonella enterica, EutT-dependent AdoCbl synthesis supports ethanolamine utilization, which contributes to gut colonization. Similarly, PduO supports 1,2-propanediol degradation in Lactobacillus reuteri and other bacteria, influencing microbial competition and host interactions.
From corrinoid adenosyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of MMAB affect AdoCbl synthesis? | MMAB knockout HEK293 cells |
| How does Phe112 mutation affect PduO activity? | PduO point-mutation (F112A) in L. reuteri |
| Can wild-type MMAB rescue MMA patient cells? | MMAB knock-in (wild-type) in patient fibroblasts |
| Where is MMAB localized? | MMAB GFP-tagged knock-in in HeLa cells |
| Does overexpression of PduO increase AdoCbl production? | PduO overexpression in E. coli |
| What is the role of EutT in ethanolamine utilization? | EutT knockout in Salmonella enterica |
How to Study the corrinoid adenosyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| HPLC/LC-MS | AdoCbl and corrinoid levels | Quantifying enzyme activity in cell lysates |
| Resonance Raman spectroscopy | Co-corrinoid coordination | Studying substrate binding |
| UV-visible spectroscopy | Redox state of corrinoid | Monitoring Co(II) reduction |
| CRISPR knockout | Gene function | Identifying essential genes in B12 metabolism |
| Metabolomics | Methylmalonic acid levels | Diagnosing MMA in cell models |
| Western blot | Protein expression | Validating knockout/overexpression |
| Enzyme kinetics | Km, Vmax, kcat | Characterizing mutants |
Enzymatic assays for corrinoid adenosyltransferase activity
Direct measurement of AdoCbl formation can be performed using HPLC or LC-MS to detect adenosylcorrinoid products. Radioactive ATP-based assays or spectrophotometric monitoring of ETF oxidation can also be used.
Spectroscopic characterization
Resonance Raman spectroscopy has been used to study the interaction between Co(II)corrinoids and PduO, revealing details of the four-coordinate substrate intermediate. UV-visible spectroscopy can monitor reduction of Co(II) to Co(I).
Genetic and CRISPR screens
CRISPR knockout screens can identify genes required for AdoCbl synthesis and function. For example, knocking out MMAB in human cells followed by metabolomic profiling can reveal methylmalonic acid accumulation.
Structural biology
X-ray crystallography and cryo-EM can provide structural insights into substrate binding and catalysis. Structures of PduO and EutT have been solved, revealing conserved folds and metal-binding sites [2,8].
How CRISPR Can Be Used to Study GO:0008817 corrinoid adenosyltransferase activity
Knockout
CRISPR knockout of MMAB in human cell lines (e.g., HEK293) can model methylmalonic acidemia and confirm the role of MMAB in AdoCbl synthesis. Knockout of bacterial pduO or eutT can reveal their roles in metabolic pathways [5,8].
Point Mutation
Introducing point mutations such as F112A in PduO can dissect the catalytic role of specific residues in corrinoid reduction and adenosylation. Disease-associated MMAB mutations can be modeled to study genotype-phenotype correlations.
Knock-in
Knock-in of wild-type MMAB into patient-derived cells can rescue the metabolic defect and validate gene function. Tagged knock-in (e.g., GFP-MMAB) allows visualization of protein localization.
Overexpression
Overexpression of PduO or EutT in E. coli or other hosts can enhance AdoCbl production for biotechnological applications [5,8]. Overexpression in mammalian cells can help study protein interactions and stability.
How EDITGENE Supports corrinoid adenosyltransferase activity Research
Researchers studying corrinoid adenosyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in AdoCbl synthesis, metabolic disease, or bacterial metabolism. EDITGENE provides comprehensive CRISPR-based services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for corrinoid adenosyltransferase activity research.
Frequently Asked Questions About corrinoid adenosyltransferase activity
What is corrinoid adenosyltransferase activity?
It is a molecular function (GO:0008817) that catalyzes the ATP-dependent reductive adenosylation of corrinoids to form adenosylcobalamin, a cofactor for B12-dependent enzymes.
What genes are involved in corrinoid adenosyltransferase activity?
Key genes include human MMAB, bacterial pduO, eutT, and cobA, which encode enzymes with this activity [1,2,5,8].
What diseases are associated with corrinoid adenosyltransferase deficiency?
Mutations in MMAB cause methylmalonic acidemia, a metabolic disorder with severe neurological symptoms.
What is the reaction catalyzed by corrinoid adenosyltransferase?
The enzyme catalyzes: 2 ATP + 2 corrinoid + reduced ETF = 2 adenosylcorrinoid + 3 H+ + oxidized ETF + 2 triphosphate.
How is corrinoid adenosyltransferase activity measured?
It can be measured by HPLC/LC-MS detection of AdoCbl, or by spectroscopic monitoring of Co(II) reduction [5,7].
What is the role of MMAB in human metabolism?
MMAB synthesizes adenosylcobalamin, which is required for methylmalonyl-CoA mutase in propionate metabolism.
Which model organisms are used to study corrinoid adenosyltransferase?
Lactobacillus reuteri (PduO) and Salmonella enterica (EutT) are common bacterial models, while human cell lines model MMAB deficiency [2,5,8].
Can CRISPR be used to study corrinoid adenosyltransferase?
Yes, CRISPR knockout, point mutation, and knock-in models are powerful tools to dissect gene function and disease mechanisms [1,2].
What is the difference between PduO and EutT?
PduO is a metal-independent enzyme from L. reuteri, while EutT from S. enterica is oxygen-labile and metal-containing [2,8].
Why is adenosylcobalamin important?
AdoCbl is a cofactor for methylmalonyl-CoA mutase and other enzymes, and its deficiency leads to metabolic disorders [3,6].
Conclusion
Corrinoid adenosyltransferase activity (GO:0008817) is a critical molecular function for adenosylcobalamin synthesis, impacting human health and microbial metabolism. Understanding its mechanism, regulation, and disease relevance provides insights into metabolic disorders and offers targets for therapeutic and biotechnological applications. EDITGENE's CRISPR services can help researchers model these pathways with precision.
References
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- 2. Mera PE et al.. 2009. Residue Phe112 of the human-type corrinoid adenosyltransferase (PduO) enzyme of Lactobacillus reuteri is critical to the formation of the four-coordinate Co(II) corrinoid substrate and to the activity of the enzyme.. Biochemistry 48(14):3138-45 PMID: 19236001
- 3. Kräutler B. 2012. Biochemistry of B12-cofactors in human metabolism.. Subcell Biochem 56:323-46 PMID: 22116707
- 4. Sato K et al.. 1980. Level of methionine synthase activity and interconversion of methylcobalamin and adenosylcobalamin in a facultative methylotroph, Protaminobacter ruber.. J Nutr Sci Vitaminol (Tokyo) 26(6):557-69 PMID: 7241237
- 5. Park K et al.. 2008. Kinetic and spectroscopic studies of the ATP:corrinoid adenosyltransferase PduO from Lactobacillus reuteri: substrate specificity and insights into the mechanism of Co(II)corrinoid reduction.. Biochemistry 47(34):9007-15 PMID: 18672897
- 6. Mascarenhas R et al.. 2022. Human B(12)-dependent enzymes: Methionine synthase and Methylmalonyl-CoA mutase.. Methods Enzymol 668:309-326 PMID: 35589199
- 7. Park K et al.. 2016. Resonance Raman spectroscopic study of the interaction between Co(II)rrinoids and the ATP:corrinoid adenosyltransferase PduO from Lactobacillus reuteri.. J Biol Inorg Chem 21(5-6):669-81 PMID: 27383231
- 8. Buan NR et al.. 2004. The eutT gene of Salmonella enterica Encodes an oxygen-labile, metal-containing ATP:corrinoid adenosyltransferase enzyme.. J Bacteriol 186(17):5708-14 PMID: 15317775
