GO:0004582 dolichyl-phosphate beta-D-mannosyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004582 describes the enzymatic activity that transfers mannose from GDP-mannose to dolichyl phosphate, forming dolichyl D-mannosyl phosphate (Dol-P-Man).
• This reaction is a committed step in the dolichol cycle, supplying mannose for N-linked glycosylation, O-mannosylation, and glycosylphosphatidylinositol (GPI) anchor biosynthesis.
• The enzyme is conserved from yeast to humans; the Saccharomyces cerevisiae enzyme was purified and characterized as a GDP-mannose:dolichyl-phosphate O-beta-D-mannosyltransferase.
• Enzyme activity is developmentally regulated in pig brain, indicating tissue- and stage-specific roles.
• Altered activity has been observed in liver preparations from patients with cystic fibrosis and diabetes mellitus, suggesting links to metabolic and genetic disorders.
• The hydrophobic domain of the yeast enzyme is not essential for activity or growth, highlighting a non-canonical structure-function relationship.
Description
Dolichyl-phosphate beta-D-mannosyltransferase (DPM synthase) catalyzes the transfer of mannose from GDP-mannose to dolichyl phosphate, yielding GDP and dolichyl D-mannosyl phosphate (Dol-P-Man). This reaction is a central step in the dolichol cycle, providing the mannose donor for multiple glycosylation pathways in the endoplasmic reticulum. The enzyme is conserved across eukaryotes, and its activity is essential for protein glycosylation, cell wall integrity, and developmental processes. Researchers study GO:0004582 to understand glycoprotein biosynthesis, congenital disorders of glycosylation, and potential therapeutic targets. The enzyme has been purified from Saccharomyces cerevisiae and shown to be a GDP-mannose:dolichyl-phosphate O-beta-D-mannosyltransferase. Its activity changes during brain development in pigs, suggesting a role in neural development. In humans, altered enzyme activity has been linked to cystic fibrosis and diabetes mellitus, underscoring its clinical relevance. The hydrophobic domain of the yeast enzyme is dispensable for activity, indicating that membrane anchoring is not strictly required for catalysis. Elevated activity in Trichoderma atroviride enhances biocontrol abilities, demonstrating its importance beyond human health. The enzyme exhibits specificity for GDP-mannose analogs, which can be exploited for inhibitor design. Given its central role in glycosylation, DPM synthase is a target for understanding and treating glycosylation disorders. This article synthesizes current knowledge on GO:0004582, covering its mechanism, key genes, disease associations, and research methods.
dolichyl-phosphate beta-D-mannosyltransferase activity At A Glance
| GO ID | GO:0004582 |
|---|---|
| GO term | dolichyl-phosphate beta-D-mannosyltransferase activity |
| Ontology | molecular_function |
| Synonym | DPM synthase activity; dolichol phosphate mannose synthase activity; GDP-mannose:dolichyl-phosphate beta-D-mannosyltransferase activity |
| Major function | Transfer of mannose from GDP-mannose to dolichyl phosphate, forming dolichyl D-mannosyl phosphate |
| Reaction | GDP-mannose + dolichyl phosphate = GDP + dolichyl D-mannosyl phosphate |
| Substrates | GDP-mannose and dolichyl phosphate |
| Products | GDP and dolichyl D-mannosyl phosphate |
| Localization | Endoplasmic reticulum membrane |
| Conservation | Conserved from yeast to humans |
What Is GO:0004582?
GO:0004582, dolichyl-phosphate beta-D-mannosyltransferase activity, is a molecular function defined as the catalysis of the reaction: GDP-mannose + dolichyl phosphate = GDP + dolichyl D-mannosyl phosphate. This activity is also known as DPM synthase or dolichol phosphate mannose synthase. It belongs to the glycosyltransferase family and is responsible for the synthesis of dolichyl D-mannosyl phosphate, a key mannose donor in the endoplasmic reticulum.
Why Is dolichyl-phosphate beta-D-mannosyltransferase activity Important in Cell Biology?
GO:0004582 is critical because the reaction it catalyzes produces dolichyl D-mannosyl phosphate, the obligate mannose donor for N-linked glycosylation, O-mannosylation, and GPI anchor biosynthesis. Without this activity, proteins cannot be properly glycosylated, leading to defective cell surface signaling, protein folding, and cell-cell interactions. The enzyme is linked to developmental processes, as shown by changes in activity during pig brain development. Clinically, altered activity has been observed in cystic fibrosis and diabetes mellitus, suggesting a role in disease pathology. In fungi, elevated activity enhances biocontrol abilities, indicating agricultural relevance. Thus, understanding GO:0004582 is essential for glycobiology, developmental biology, and disease research.
• Provides the mannose donor for N-linked glycosylation, affecting protein folding and stability.
• Essential for O-mannosylation of proteins, including those in the nervous system.
• Required for GPI anchor biosynthesis, which anchors proteins to the cell membrane.
• Shows developmental regulation in pig brain, implicating roles in neurodevelopment.
• Altered activity in cystic fibrosis and diabetes mellitus suggests links to metabolic and genetic disorders.
• The hydrophobic domain is not essential for activity, offering insights into enzyme engineering.
• Elevated activity in Trichoderma atroviride improves biocontrol, with agricultural applications.
• Specificity for GDP-mannose analogs can guide design of enzyme inhibitors.
• Conserved across eukaryotes, making yeast a useful model for studying human glycosylation.
• Potential target for congenital disorders of glycosylation and cancer.
Molecular Mechanism of dolichyl-phosphate beta-D-mannosyltransferase activity
Substrate Recognition and Binding
In simple terms: The enzyme grabs GDP-mannose and dolichyl phosphate to start the reaction.
DPM synthase specifically binds GDP-mannose and dolichyl phosphate. The enzyme recognizes the guanosine diphosphate moiety of GDP-mannose, as shown by studies with deoxy and deoxyfluoro analogs that affect binding specificity. Dolichyl phosphate is a long-chain polyisoprenoid that anchors the substrate in the membrane. The enzyme's active site accommodates both substrates, facilitating the transfer of mannose.
Catalytic Transfer of Mannose
In simple terms: The enzyme snips off mannose from GDP-mannose and attaches it to dolichyl phosphate.
The catalytic mechanism involves the nucleophilic attack of the phosphate oxygen of dolichyl phosphate on the anomeric carbon of GDP-mannose, resulting in the formation of a beta-mannosyl linkage and release of GDP. This reaction is a beta-D-mannosyltransferase activity, as defined by GO:0004582. The enzyme does not require a divalent metal ion for activity, distinguishing it from some other glycosyltransferases.
Role of the Hydrophobic Domain
In simple terms: The enzyme has a greasy part that helps it sit in the membrane, but this part is not needed for its chemical work.
The yeast DPM synthase contains a hydrophobic domain that anchors it to the endoplasmic reticulum membrane. However, deletion of this domain does not abolish enzyme activity or growth, indicating that membrane anchoring is not essential for catalysis. This suggests that the catalytic domain is sufficient for mannose transfer, and the hydrophobic region may play a regulatory or localization role.
Product Release and Dolichol Cycle Integration
In simple terms: After making Dol-P-Man, the enzyme releases it to be used in building sugar chains on proteins.
The product, dolichyl D-mannosyl phosphate (Dol-P-Man), is released and serves as a mannose donor for various glycosyltransferases in the endoplasmic reticulum. It is used in N-linked glycosylation, O-mannosylation, and GPI anchor synthesis. The enzyme thus integrates into the dolichol cycle, which recycles dolichol phosphate for further rounds of glycosylation.
Regulation of Enzyme Activity
In simple terms: The enzyme's activity can change depending on the cell's needs and developmental stage.
DPM synthase activity is developmentally regulated, as shown by changes in pig brain during development. In disease states such as cystic fibrosis and diabetes mellitus, activity levels are altered in liver preparations. In Trichoderma atroviride, elevated activity enhances biocontrol abilities, indicating that activity can be modulated for functional outcomes. The enzyme's specificity for GDP-mannose analogs suggests that substrate availability and structural analogs can influence activity.
Key Genes Involved in GO:0004582 dolichyl-phosphate beta-D-mannosyltransferase activity
The following genes and proteins are directly involved in or regulate dolichyl-phosphate beta-D-mannosyltransferase activity.
| Gene | Major Role | Research Relevance |
|---|---|---|
| DPM1 | Catalytic subunit of DPM synthase in yeast and humans | Mutations cause congenital disorders of glycosylation; target for glycosylation studies |
| DPM2 | Regulatory subunit that stabilizes DPM1 | Required for optimal enzyme activity; knockout affects glycosylation |
| DPM3 | Stabilizes DPM1 and DPM2 complex | Mutations linked to muscular dystrophy; model for glycosylation disorders |
| ALG1 | Mannosyltransferase in N-glycan synthesis | Downstream of DPM synthase; cooperates in glycosylation |
| ALG2 | Mannosyltransferase in N-glycan synthesis | Uses Dol-P-Man as donor; related to congenital disorders |
| ALG3 | Mannosyltransferase in N-glycan synthesis | Requires Dol-P-Man; mutations cause CDG |
| PIGB | GPI anchor biosynthesis | Uses Dol-P-Man for GPI mannosylation |
| PIGM | GPI anchor biosynthesis | Uses Dol-P-Man; defects cause GPI deficiency |
| PIGV | GPI anchor biosynthesis | Uses Dol-P-Man; mutations cause hyperphosphatasia |
| POMT1 | O-mannosyltransferase | Uses Dol-P-Man for O-mannosylation; mutations cause Walker-Warburg syndrome |
| POMT2 | O-mannosyltransferase | Partners with POMT1; uses Dol-P-Man |
| SEC59 | Dolichol kinase in yeast | Provides dolichyl phosphate for DPM synthase |
| RER2 | Cis-prenyltransferase in yeast | Synthesizes dolichol; affects substrate availability |
| SRT1 | Cis-prenyltransferase in yeast | Synthesizes dolichol; affects DPM synthase activity |
| DPM1 (S. cerevisiae) | GDP-mannose:dolichyl-phosphate O-beta-D-mannosyltransferase | Purified and characterized; model for enzyme structure |
| DPM1 (T. atroviride) | DPM synthase | Overexpression enhances biocontrol |
| DPM1 (pig) | DPM synthase | Developmental regulation in brain |
How Is dolichyl-phosphate beta-D-mannosyltransferase activity Regulated?
DPM synthase activity is regulated at multiple levels. Developmentally, activity changes in pig brain, suggesting stage-specific expression or post-translational modification. In disease states such as cystic fibrosis and diabetes mellitus, activity is altered in liver, indicating metabolic regulation. The enzyme's hydrophobic domain may influence localization but is not essential for activity. In Trichoderma atroviride, elevated activity enhances biocontrol, suggesting that overexpression can modulate function. Substrate availability, particularly GDP-mannose and dolichyl phosphate, also regulates flux through the reaction.
dolichyl-phosphate beta-D-mannosyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| DPM1 | Congenital disorder of glycosylation (CDG) | Knockout or point-mutation in human cell lines; yeast models |
| DPM2 | CDG with seizures and developmental delay | Knockout in HEK293 or patient-derived fibroblasts |
| DPM3 | Muscular dystrophy with hypoglycosylation | Knock-in of patient mutations in mouse models |
| POMT1 | Walker-Warburg syndrome | Knockout in zebrafish or mouse |
| PIGM | GPI deficiency with thrombosis | Point mutation in hematopoietic cell lines |
Congenital Disorders of Glycosylation (CDG)
Mutations in DPM1, DPM2, and DPM3 cause CDG, a group of inherited disorders characterized by defective glycosylation of proteins and lipids. These mutations reduce DPM synthase activity, leading to insufficient Dol-P-Man for N-glycosylation, O-mannosylation, and GPI anchor synthesis. Patients present with developmental delay, seizures, and multisystemic abnormalities.
Cystic Fibrosis and Diabetes Mellitus
Altered DPM synthase activity has been observed in liver preparations from patients with cystic fibrosis and diabetes mellitus. Although the exact mechanism is unclear, these findings suggest that DPM synthase may contribute to the pathophysiology of these metabolic and genetic disorders.
Muscular Dystrophy
Mutations in DPM3, a subunit of DPM synthase, are linked to muscular dystrophy with hypoglycosylation of alpha-dystroglycan. This highlights the importance of DPM synthase in muscle integrity and the potential for therapeutic targeting.
Cancer and Glycosylation
Altered glycosylation is a hallmark of cancer, and DPM synthase activity may influence tumor progression through changes in cell surface glycans. Although direct evidence is limited, targeting DPM synthase could modulate glycosylation-dependent signaling in cancer cells.
From dolichyl-phosphate beta-D-mannosyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of DPM1 affect glycosylation and cell viability? | CRISPR knockout in HEK293 or HeLa cells |
| What is the effect of a specific DPM1 point mutation on enzyme activity? | Point mutation knock-in in yeast or human cells |
| Can tagged DPM1 be used to study localization? | Knock-in of GFP or FLAG tag at endogenous locus |
| Does overexpression of DPM1 enhance glycosylation? | Overexpression in Trichoderma atroviride or mammalian cells |
| What is the developmental role of DPM synthase in brain? | Conditional knockout in mouse brain |
| How does DPM synthase activity change in diabetes? | Liver-specific knockout or overexpression in mouse models |
How to Study the dolichyl-phosphate beta-D-mannosyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzymatic assay with radiolabeled GDP-mannose | DPM synthase activity | Kinetic studies and inhibitor screening |
| Lectin blotting | Glycosylation status of proteins | Detection of glycosylation defects in CDG |
| Mass spectrometry | Glycan structures | Detailed glycomic analysis |
| CRISPR-Cas9 knockout | Gene function | Loss-of-function studies in cell lines |
| CRISPR-Cas9 knock-in | Mutant protein expression | Modeling patient mutations |
| RNA-seq | Transcriptional changes | Pathway analysis upon DPM perturbation |
| Proteomics | Protein expression and modifications | Identifying glycosylation targets |
| Fluorescence microscopy | Subcellular localization | Tagged DPM1 localization studies |
Enzymatic Activity Assays
DPM synthase activity can be measured using radiolabeled GDP-[3H]mannose and dolichyl phosphate, followed by extraction and quantification of Dol-P-Man. This assay is used to assess enzyme kinetics and inhibitor effects.
Glycosylation Analysis
Changes in glycosylation due to altered DPM synthase activity can be analyzed by lectin blotting, mass spectrometry, or HPLC of released glycans. These methods reveal defects in N-linked, O-linked, and GPI-anchored glycans.
CRISPR-Cas9 Genome Editing
CRISPR-Cas9 is used to generate knockout, point mutation, or knock-in models of DPM1, DPM2, and DPM3 to study their roles in glycosylation and disease. These models help establish causality between gene variants and phenotypes.
Transcriptomics and Proteomics
RNA-seq and proteomics can identify changes in glycosylation-related genes and proteins upon DPM synthase perturbation. These approaches provide systems-level insights into the dolichol cycle.
How CRISPR Can Be Used to Study GO:0004582 dolichyl-phosphate beta-D-mannosyltransferase activity
Knockout
CRISPR knockout of DPM1, DPM2, or DPM3 in human cell lines abolishes DPM synthase activity, leading to defective glycosylation and cell death or growth arrest. These models are used to study the essentiality of the enzyme and to identify compensatory pathways.
Point Mutation
Point mutations identified in CDG patients can be introduced into DPM1 or DPM3 using CRISPR knock-in to model the disease in vitro. These models help determine the pathogenicity of specific variants and test therapeutic interventions.
Knock-in
Knock-in of epitope tags (e.g., FLAG, GFP) at the endogenous DPM1 locus allows for real-time tracking of enzyme localization and interaction partners. This approach preserves endogenous regulation and provides insights into enzyme dynamics.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of DPM1 can increase DPM synthase activity, enhancing glycosylation capacity. This is useful for bioproduction of glycoproteins and for studying the effects of elevated activity in disease models.
How EDITGENE Supports dolichyl-phosphate beta-D-mannosyltransferase activity Research
Researchers studying dolichyl-phosphate beta-D-mannosyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in glycosylation disorders, developmental processes, or metabolic diseases. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models, enabling functional validation and mechanistic studies.
Contact EDITGENE today to design your custom CRISPR model for dolichyl-phosphate beta-D-mannosyltransferase activity research.
Frequently Asked Questions About dolichyl-phosphate beta-D-mannosyltransferase activity
What is dolichyl-phosphate beta-D-mannosyltransferase activity?
It is the enzymatic activity that transfers mannose from GDP-mannose to dolichyl phosphate, forming dolichyl D-mannosyl phosphate, as defined by GO:0004582.
What genes are involved in dolichyl-phosphate beta-D-mannosyltransferase activity?
Key genes include DPM1, DPM2, and DPM3, which encode subunits of the DPM synthase complex.
What is the role of DPM synthase in glycosylation?
DPM synthase produces Dol-P-Man, the mannose donor for N-linked glycosylation, O-mannosylation, and GPI anchor biosynthesis.
How is dolichyl-phosphate beta-D-mannosyltransferase activity measured?
It is typically measured using radiolabeled GDP-mannose and dolichyl phosphate, followed by quantification of the Dol-P-Man product.
What diseases are associated with DPM synthase mutations?
Mutations in DPM1, DPM2, and DPM3 cause congenital disorders of glycosylation, and DPM3 mutations are linked to muscular dystrophy.
Is the hydrophobic domain of DPM synthase required for activity?
No, studies in yeast show that the hydrophobic domain is not essential for enzyme activity or growth.
How is DPM synthase activity regulated during development?
Activity changes in pig brain during development, indicating developmental regulation.
Can DPM synthase activity be altered in diabetes?
Yes, altered activity has been observed in liver preparations from patients with diabetes mellitus.
What model organisms are used to study DPM synthase?
Saccharomyces cerevisiae, Trichoderma atroviride, pig brain, and human cell lines are commonly used.
What CRISPR services are available for studying DPM synthase?
EDITGENE offers knockout, point mutation, knock-in, overexpression, and library screening services for DPM synthase and related genes.
Conclusion
GO:0004582, dolichyl-phosphate beta-D-mannosyltransferase activity, is a fundamental enzymatic activity in the dolichol cycle, essential for protein glycosylation and cellular function. Its conservation across eukaryotes and links to human diseases such as CDG and muscular dystrophy make it a critical research target. Understanding its mechanism, regulation, and disease associations requires robust experimental models, which can be generated using CRISPR-based approaches. EDITGENE provides comprehensive services to support such research, from knockout and point mutation models to library screening and bioinformatics.
References
- 1. Haselbeck A. 1989. Purification of GDP mannose:dolichyl-phosphate O-beta-D-mannosyltransferase from Saccharomyces cerevisiae.. Eur J Biochem 181(3):663-8 PMID: 2659345
- 2. Harford JB et al.. 1980. A developmental change in dolichyl phosphate mannose synthase activity in pig brain.. Biochem J 188(2):481-90 PMID: 7396876
- 3. Alhadeff JA et al.. 1983. Dolichyl phosphate-mannosyltransferase and dolichyl phosphate-N-acetylglucosaminyltransferase activities in liver preparations from normal controls and patients with cystic fibrosis and diabetes mellitus.. Clin Chim Acta 134(1-2):1-9 PMID: 6228343
- 4. Zimmerman JW et al.. 1993. The hydrophobic domain of dolichyl-phosphate-mannose synthase is not essential for enzyme activity or growth in Saccharomyces cerevisiae.. J Biol Chem 268(22):16746-53 PMID: 8344954
- 5. Zembek P et al.. 2011. Elevated activity of dolichyl phosphate mannose synthase enhances biocontrol abilities of Trichoderma atroviride.. Mol Plant Microbe Interact 24(12):1522-9 PMID: 21770768
- 6. McDowell W et al.. 1989. Specificity of GDP-Man:dolichyl-phosphate mannosyltransferase for the guanosine diphosphate esters of mannose analogues containing deoxy and deoxyfluoro substituents.. FEBS Lett 243(2):413-6 PMID: 2917659
- 7. Banerjee DK et al.. 2017. Dolichol phosphate mannose synthase: a Glycosyltransferase with Unity in molecular diversities.. Glycoconj J 34(4):467-479 PMID: 28616799
