GO:0004476 mannose-6-phosphate isomerase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004476 mannose-6-phosphate isomerase activity catalyzes the reversible interconversion of D-mannose 6-phosphate and D-fructose 6-phosphate.
• The enzyme is also known as phosphomannose isomerase (PMI) and is encoded by the MPI gene in humans.
• MPI activity is essential for mannose metabolism and protein glycosylation, linking sugar metabolism to cellular proteostasis.
• Inhibition or loss of MPI activity sensitizes acute myeloid leukemia cells to therapy by driving ferroptotic cell death.
• Thermostable MPI enzymes from Thermus thermophilus and Bacillus amyloliquefaciens are used in industrial L-ribose and fructose-6-phosphate production.
• Research models include CRISPR knockout, point mutation, knock-in, and overexpression cell lines to dissect MPI function in disease.
Description
Mannose-6-phosphate isomerase activity (GO:0004476) is a molecular function that catalyzes the reversible isomerization of D-mannose 6-phosphate to D-fructose 6-phosphate. This reaction is a key step in mannose metabolism, allowing mannose to enter glycolysis and glycosylation pathways. The enzyme is widely conserved across species, from bacteria to humans, and is known as phosphomannose isomerase (PMI). In humans, MPI deficiency is associated with congenital disorders of glycosylation, and recent studies have highlighted its role in cancer metabolism. Understanding GO:0004476 is therefore important for researchers studying metabolic reprogramming, glycosylation, and therapeutic targeting.
mannose-6-phosphate isomerase activity At A Glance
| GO ID | GO:0004476 |
|---|---|
| GO term | mannose-6-phosphate isomerase activity |
| Ontology | molecular_function |
| Synonym | D-mannose-6-phosphate aldose-ketose-isomerase activity; D-mannose-6-phosphate ketol-isomerase activity; mannose phosphate isomerase activity; phosphohexoisomerase activity; phosphohexomutase activity; phosphomannoisomerase activity; phosphomannose isomerase activity |
| Major function | Catalysis of the reversible isomerization of D-mannose 6-phosphate to D-fructose 6-phosphate |
| EC number | 5.3.1.8 |
| Reaction | D-mannose 6-phosphate = D-fructose 6-phosphate |
| Pathway | Mannose metabolism, glycolysis, glycosylation |
| Human gene | MPI (mannose phosphate isomerase) |
What Is GO:0004476?
Mannose-6-phosphate isomerase activity (GO:0004476) is defined as the catalysis of the reaction: D-mannose 6-phosphate = D-fructose 6-phosphate. This enzymatic activity enables the interconversion between a mannose derivative and a fructose derivative, both of which are phosphorylated sugars involved in central carbon metabolism.
Why Is mannose-6-phosphate isomerase activity Important in Cell Biology?
Mannose-6-phosphate isomerase activity is critical for maintaining the balance between mannose and fructose metabolism, influencing glycolysis, glycosylation, and cellular stress responses. Dysregulation of this activity has been implicated in cancer, where mannose metabolism inhibition can sensitize leukemia cells to therapy. Additionally, the enzyme is a target for industrial biocatalysis, enabling efficient production of rare sugars and phosphorylated metabolites.
• Essential for mannose catabolism and entry into glycolysis.
• Required for protein glycosylation, affecting cell surface and secreted proteins.
• Loss of MPI activity causes congenital disorders of glycosylation in humans.
• MPI inhibition sensitizes acute myeloid leukemia cells to chemotherapy via ferroptosis.
• Thermostable MPI variants are used for industrial L-ribose production.
• Bacterial MPI enzymes enable efficient fructose-6-phosphate production.
• MPI polymorphism in baboons affects erythrocyte enzyme activity.
• Encapsulation of MPI in yeast spores enhances L-ribose bioconversion.
• MPI functional status shapes the proteome and degradome of melanoma cells.
• MPI is a potential therapeutic target in metabolic diseases and cancer.
What Happens During mannose-6-phosphate isomerase activity?
Substrate Binding and Isomerization
In simple terms: The enzyme grabs mannose-6-phosphate and rearranges it into fructose-6-phosphate.
Mannose-6-phosphate isomerase binds D-mannose 6-phosphate and catalyzes its reversible isomerization to D-fructose 6-phosphate. This reaction involves an aldose-ketose isomerization mechanism, where the enzyme stabilizes the transition state to facilitate the conversion.
Role in Mannose Metabolism
In simple terms: This step lets mannose enter the main sugar-burning pathway.
By converting mannose-6-phosphate to fructose-6-phosphate, the enzyme channels mannose into glycolysis. This is essential for energy production and for providing precursors for glycosylation.
Impact on Glycosylation
In simple terms: The enzyme helps build sugar chains on proteins.
Fructose-6-phosphate produced by MPI can be used for N-linked glycosylation and other glycosylation pathways. Disruption of MPI activity alters the proteome and degradome, affecting cell surface proteins and secreted factors.
Metabolic Stress and Ferroptosis
In simple terms: Blocking this enzyme can make cancer cells die from iron-dependent stress.
Inhibition of mannose metabolism, including MPI activity, sensitizes acute myeloid leukemia cells to therapy by driving ferroptotic cell death. This links MPI function to redox balance and lipid peroxidation.
Key Genes Involved in GO:0004476 mannose-6-phosphate isomerase activity
The following genes and proteins are directly or indirectly associated with mannose-6-phosphate isomerase activity and its biological roles.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MPI | Encodes mannose-6-phosphate isomerase; catalyzes mannose-6-phosphate to fructose-6-phosphate | Target for cancer metabolism and glycosylation studies |
| CREG1 | Promotes lysosomal biogenesis and function; may interact with mannose-6-phosphate pathways | Potential link between lysosomal function and mannose metabolism |
| Thermus thermophilus MPI | Thermostable mannose-6-phosphate isomerase | Industrial L-ribose production |
| Bacillus amyloliquefaciens MPI | Mannose-6-phosphate isomerase for fructose-6-phosphate production | Biocatalysis and rare sugar synthesis |
| Yeast MPI | Encapsulated in spores for L-ribose production | Biotechnological application in sugar conversion |
| Baboon MPI | Polymorphic mannose-6-phosphate isomerase in erythrocytes | Genetic variation and enzyme activity studies |
| Human MPI | Mannose phosphate isomerase; mutations cause MPI-CDG | Congenital disorders of glycosylation research |
| MPI R142N mutant | Increased L-ribose production | Protein engineering for industrial biocatalysis |
| MPI in melanoma | Functional status shapes proteome and degradome | Cancer proteomics and drug response |
| MPI in AML | Mannose metabolism inhibition drives ferroptosis | Leukemia therapy sensitization |
| Phosphomannose isomerase | Synonym for MPI; essential for mannose metabolism | Enzyme characterization and inhibitor development |
| D-mannose-6-phosphate aldose-ketose-isomerase | Alternative name for MPI | Enzymology and kinetic studies |
| Phosphohexoisomerase | Synonym reflecting broader hexose isomerase activity | Historical enzyme nomenclature |
| Phosphohexomutase | Synonym for MPI | Enzyme classification studies |
| Phosphomannoisomerase | Synonym for MPI | Biochemical assays |
| MPI in yeast spores | Encapsulated enzyme for L-ribose production | Whole-cell biocatalysis |
| Thermostable MPI | From Thermus thermophilus; used in L-ribose production | Industrial enzyme development |
| Bacterial MPI | From Bacillus amyloliquefaciens; fructose-6-phosphate production | Metabolic engineering |
How Is mannose-6-phosphate isomerase activity Regulated?
Mannose-6-phosphate isomerase activity is regulated at the transcriptional and post-transcriptional levels, and its functional status can be modulated by metabolic cues. In melanoma cells, mannose treatment induces proteome and degradome rearrangements dependent on MPI activity. In acute myeloid leukemia, inhibition of mannose metabolism sensitizes cells to therapy, suggesting that MPI activity is a determinant of drug response. Additionally, encapsulation of MPI in yeast spores enhances its stability and reusability for bioconversion.
mannose-6-phosphate isomerase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| MPI | MPI-CDG (congenital disorder of glycosylation) | Patient-derived fibroblasts; CRISPR knockout of MPI in cell lines |
| MPI | Acute myeloid leukemia; ferroptosis sensitization | AML cell lines with MPI knockout or point mutation |
| MPI | Melanoma proteome and degradome remodeling | Melanoma cells overexpressing or lacking MPI |
| MPI | Baboon erythrocyte polymorphism | Baboon erythrocyte enzyme activity assays |
| MPI | Industrial L-ribose production | Thermus thermophilus MPI mutants in E. coli |
Mannose-6-phosphate isomerase deficiency and congenital disorders of glycosylation
Mutations in the MPI gene cause MPI-CDG, a congenital disorder of glycosylation characterized by protein-losing enteropathy, hypoglycemia, and liver fibrosis. Loss of MPI activity impairs glycosylation and mannose metabolism.
Cancer metabolism and ferroptosis
In acute myeloid leukemia, inhibition of mannose metabolism, including MPI activity, sensitizes cells to therapy by driving ferroptotic cell death. This highlights MPI as a potential therapeutic target in leukemia.
Melanoma proteome remodeling
MPI functional status shapes the proteome and degradome of mannose-treated melanoma cells, affecting protein turnover and cellular stress responses. This suggests a role for MPI in melanoma biology.
From mannose-6-phosphate isomerase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does MPI loss affect glycosylation and cell viability? | CRISPR knockout of MPI in human cell lines |
| Does a specific MPI point mutation alter enzyme kinetics? | Point mutation knock-in of MPI variants |
| Can MPI overexpression rescue metabolic defects? | Overexpression of wild-type MPI in patient cells |
| How does MPI activity affect drug response in leukemia? | MPI knockout or inhibition in AML cell lines |
| Can thermostable MPI improve L-ribose production? | Bacterial expression of Thermus thermophilus MPI mutants |
| Does MPI encapsulation enhance bioconversion? | Yeast spores encapsulating MPI |
How to Study the mannose-6-phosphate isomerase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzyme-coupled assay | Mannose-6-phosphate isomerase activity | Kinetic characterization of wild-type and mutant MPI |
| Proteomics | Protein abundance changes | Proteome remodeling in MPI-altered cells |
| Degradome analysis | Protein turnover rates | Degradome changes in melanoma cells |
| Metabolomics | Metabolite levels | Mannose metabolism and glycolysis flux |
| CRISPR knockout screening | Gene essentiality and drug synergy | Identifying sensitizers to MPI inhibition |
| Western blot | Protein expression | Validation of MPI knockout or overexpression |
| L-ribose production assay | Bioconversion yield | Industrial application of thermostable MPI |
| Fructose-6-phosphate production | Enzymatic product formation | Biocatalysis with bacterial MPI |
Enzymatic activity assays
Mannose-6-phosphate isomerase activity can be measured by coupling the conversion of mannose-6-phosphate to fructose-6-phosphate to NADH-dependent reactions. These assays are used to characterize wild-type and mutant enzymes.
Proteomics and degradome analysis
Proteomic and degradomic profiling of cells with altered MPI activity reveals changes in protein abundance and turnover. This approach has been applied to melanoma cells treated with mannose.
Metabolic flux analysis
Isotope tracing and metabolomics can quantify the contribution of MPI to glycolytic flux and glycosylation precursor pools. Such methods help link MPI activity to cellular metabolism.
CRISPR-based genetic screens
CRISPR knockout screens can identify genes that synergize with MPI inhibition, revealing pathways that sensitize cancer cells to therapy. These screens are valuable for target discovery.
How CRISPR Can Be Used to Study GO:0004476 mannose-6-phosphate isomerase activity
Knockout
CRISPR knockout of MPI can abolish mannose-6-phosphate isomerase activity, leading to impaired glycosylation and metabolic rewiring. Such models are used to study MPI-CDG and cancer metabolism.
Point Mutation
Point mutations in MPI, such as R142N, can alter enzyme activity and substrate specificity. CRISPR-mediated point mutation knock-in allows precise functional dissection of MPI variants.
Knock-in
Knock-in of tagged MPI (e.g., GFP or FLAG) enables visualization and immunoprecipitation of the enzyme. This helps track MPI localization and interactions.
Overexpression
Overexpression of wild-type or mutant MPI can rescue or exacerbate phenotypes in cellular models. This is useful for testing gain-of-function effects and drug responses.
How EDITGENE Supports mannose-6-phosphate isomerase activity Research
Researchers studying mannose-6-phosphate isomerase activity-related genes often need to determine whether a candidate gene is causally involved in metabolic and disease phenotypes. EDITGENE provides comprehensive CRISPR services to generate precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for mannose-6-phosphate isomerase activity research.
Frequently Asked Questions About mannose-6-phosphate isomerase activity
What is mannose-6-phosphate isomerase activity?
Mannose-6-phosphate isomerase activity (GO:0004476) is the catalysis of the reversible conversion of D-mannose 6-phosphate to D-fructose 6-phosphate.
What genes are involved in mannose-6-phosphate isomerase activity?
The primary gene is MPI, which encodes mannose phosphate isomerase in humans. Other species have orthologs such as Thermus thermophilus MPI.
What is the function of MPI in cells?
MPI enables mannose to enter glycolysis and provides fructose-6-phosphate for glycosylation.
How is mannose-6-phosphate isomerase activity measured?
It is typically measured using enzyme-coupled assays that monitor the conversion of mannose-6-phosphate to fructose-6-phosphate.
What diseases are associated with MPI deficiency?
MPI deficiency causes MPI-CDG, a congenital disorder of glycosylation with protein-losing enteropathy and liver fibrosis.
Can MPI be targeted for cancer therapy?
Inhibition of mannose metabolism, including MPI, sensitizes acute myeloid leukemia cells to therapy by inducing ferroptosis.
What are the industrial applications of MPI?
Thermostable MPI enzymes are used for L-ribose production and fructose-6-phosphate synthesis.
How can CRISPR be used to study MPI?
CRISPR knockout, point mutation, knock-in, and overexpression models allow functional dissection of MPI in metabolism and disease.
What is the reaction catalyzed by mannose-6-phosphate isomerase?
The enzyme catalyzes D-mannose 6-phosphate = D-fructose 6-phosphate.
Are there species differences in MPI?
Yes, MPI is conserved but thermostable variants exist in Thermus thermophilus and Bacillus amyloliquefaciens.
Conclusion
Mannose-6-phosphate isomerase activity (GO:0004476) is a fundamental enzymatic function linking mannose metabolism to glycolysis and glycosylation. Its role in cancer metabolism and congenital disorders makes it a compelling target for therapeutic and biotechnological applications. CRISPR-based models and advanced omics methods are essential for further dissecting its mechanisms and disease relevance.
References
- 1. de Vasconcellos Racorti N et al.. 2024. Mannose-6-Phosphate Isomerase Functional Status Shapes a Rearrangement in the Proteome and Degradome of Mannose-Treated Melanoma Cells.. J Proteome Res 23(11):5177-5192 PMID: 39420811
- 2. Li Z et al.. 2020. Encapsulation of Mannose-6-phosphate Isomerase in Yeast Spores and Its Application in l-Ribose Production.. J Agric Food Chem 68(25):6892-6899 PMID: 32486647
- 3. Liu J et al.. 2021. CREG1 promotes lysosomal biogenesis and function.. Autophagy 17(12):4249-4265 PMID: 33966596
- 4. VandeBerg JL et al.. 1990. Mannose-6-phosphate isomerase polymorphism in baboon erythrocytes.. Biochem Genet 28(9-10):495-501 PMID: 2085314
- 5. Yeom SJ et al.. 2011. Characterization of a mannose-6-phosphate isomerase from Thermus thermophilus and increased L-ribose production by its R142N mutant.. Appl Environ Microbiol 77(3):762-7 PMID: 21115698
- 6. Woodley K et al.. 2023. Mannose metabolism inhibition sensitizes acute myeloid leukaemia cells to therapy by driving ferroptotic cell death.. Nat Commun 14(1):2132 PMID: 37059720
- 7. Yeom SJ et al.. 2011. Molecular characterization of a novel thermostable mannose-6-phosphate isomerase from Thermus thermophilus.. Biochimie 93(10):1659-67 PMID: 21729734
- 8. Sigdel S et al.. 2015. Characterization of a Mannose-6-Phosphate Isomerase from Bacillus amyloliquefaciens and Its Application in Fructose-6-Phosphate Production.. PLoS One 10(7):e0131585 PMID: 26171785
