GO:0004571 mannosyl-oligosaccharide 1,2-alpha-mannosidase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004571 describes the enzymatic activity that removes terminal (1->2)-linked alpha-D-mannose residues from oligo-mannose oligosaccharides, a key step in N-glycan processing.
• The activity is widely conserved, found in fungi, plants, insects, and mammals, and is essential for glycoprotein maturation [3,5].
• Enzymes with this activity include mannosidase I (ManI) in the endoplasmic reticulum and Golgi, such as yeast Mns1p and mammalian MAN1A1/MAN1B1.
• Structural and mutagenesis studies have identified catalytic residues and a mechanism involving calcium or other cofactors, depending on the enzyme source [4,6].
• Dysregulation of this activity is linked to congenital disorders of glycosylation and cancer, making it a target for therapeutic and diagnostic research.
• CRISPR-based knockout, point mutation, and knock-in models are powerful tools to dissect the cellular roles of this activity and its genes [3,4].
Description
Mannosyl-oligosaccharide 1,2-alpha-mannosidase activity (GO:0004571) is a fundamental enzymatic function in the N-linked glycosylation pathway, responsible for trimming specific mannose residues from oligosaccharide precursors on glycoproteins. This activity is critical for the proper folding, stability, and function of numerous secreted and membrane proteins, and its disruption can lead to a range of human diseases. Researchers study this activity to understand glycoprotein quality control, cellular stress responses, and the molecular basis of glycosylation disorders [3,5]. The enzyme has been characterized from diverse organisms, including fungi, plants, and mammals, revealing conserved catalytic mechanisms and structural features [4,6]. Recent advances in CRISPR gene editing have enabled precise manipulation of genes encoding this activity, facilitating functional studies and disease modeling.
mannosyl-oligosaccharide 1,2-alpha-mannosidase activity At A Glance
| GO ID | GO:0004571 |
|---|---|
| GO term | mannosyl-oligosaccharide 1,2-alpha-mannosidase activity |
| Ontology | molecular_function |
| Synonym | 1,2-alpha-mannosidase; ManI; mannosidase I; glycoprotein processing mannosidase I |
| Major function | Hydrolysis of terminal (1->2)-linked alpha-D-mannose residues in oligo-mannose oligosaccharides |
| EC number | 3.2.1.113 |
| Cofactor | Calcium (for some enzymes) or no metal requirement (for others) [4,6] |
| Subcellular location | Endoplasmic reticulum and Golgi apparatus |
| Representative genes | MAN1A1, MAN1B1, MAN1C1 (human); MNS1, MNS2, MNS3 (yeast) |
What Is GO:0004571?
GO:0004571, mannosyl-oligosaccharide 1,2-alpha-mannosidase activity, is defined as the catalysis of the hydrolysis of terminal (1->2)-linked alpha-D-mannose residues in an oligo-mannose oligosaccharide. This exoglycosidase activity specifically cleaves alpha-1,2-mannosidic linkages, releasing free mannose and progressively trimming the oligosaccharide chain. It is a key step in the processing of N-glycans in the endoplasmic reticulum and Golgi apparatus, and is also known by synonyms such as mannosidase I, ManI, and glycoprotein processing mannosidase I.
Why Is mannosyl-oligosaccharide 1,2-alpha-mannosidase activity Important in Cell Biology?
Mannosyl-oligosaccharide 1,2-alpha-mannosidase activity is essential for the N-glycan processing pathway, which ensures proper protein folding and function in the secretory pathway. Defects in this activity cause congenital disorders of glycosylation, characterized by developmental delay, immune dysfunction, and multi-organ abnormalities. Additionally, altered expression of mannosidases is observed in various cancers, where they influence cell adhesion, migration, and metastasis. Understanding this activity provides insights into glycobiology, protein quality control, and potential therapeutic targets [3,5].
• Critical for N-linked glycosylation and glycoprotein maturation.
• Mutations in MAN1B1 cause congenital disorder of glycosylation type IIb.
• Altered mannosidase expression is linked to cancer progression and metastasis.
• Plays a role in endoplasmic reticulum-associated degradation (ERAD) of misfolded glycoproteins.
• Target for antifungal drugs, as fungal mannosidases are essential for cell wall integrity [1,8].
• Involved in viral envelope glycoprotein processing, affecting infectivity.
• Used as a tool enzyme in glycobiology for glycan remodeling.
• Potential biomarker for glycosylation disorders and cancer.
• Model enzyme for studying glycosidase mechanism and inhibition.
• Enables biotechnological applications in glycoprotein production.
Molecular Mechanism of mannosyl-oligosaccharide 1,2-alpha-mannosidase activity
Substrate Recognition and Binding
In simple terms: The enzyme grabs onto a sugar chain and positions a specific mannose for cutting.
The enzyme recognizes oligo-mannose oligosaccharides with terminal alpha-1,2-linked mannose residues, such as Man9GlcNAc2. Structural studies of Trichoderma reesei alpha-1,2-mannosidase reveal a conserved (alpha/alpha)7 barrel fold that accommodates the substrate in a deep cleft, allowing cleavage of four consecutive mannose residues. The active site contains acidic residues that interact with the sugar hydroxyls, ensuring specificity for the alpha-1,2 linkage.
Catalytic Mechanism and Cofactors
In simple terms: The enzyme uses a pair of acidic amino acids to break the sugar bond, sometimes with help from a calcium ion.
Hydrolysis proceeds via a general acid-base mechanism, typically involving two glutamate or aspartate residues. In Ca2+-independent 1,2-alpha-D-mannosidase from Aspergillus saitoi, site-directed mutagenesis identified Glu-411 and Glu-476 as essential catalytic residues. In contrast, some mannosidases require calcium for activity, where the metal ion stabilizes the substrate and transition state. The reaction releases free mannose and shortens the oligosaccharide chain.
Enzyme Classes and Localization
In simple terms: Different versions of this enzyme work in different parts of the cell to trim sugars at the right time.
Mannosidase I (ManI) enzymes are classified into ER and Golgi types. In Saccharomyces cerevisiae, Mns1p is an ER alpha-1,2-mannosidase involved in N-glycan processing, while Mns2p and Mns3p act in the Golgi. Mammalian cells express multiple isoforms, including MAN1A1, MAN1B1, and MAN1C1, which differ in tissue distribution and substrate specificity. These enzymes are type II membrane proteins with a short cytoplasmic tail, a transmembrane domain, and a large luminal catalytic domain.
Regulation and Quality Control
In simple terms: The cell controls how much of this enzyme is made and when it acts, especially under stress.
Expression of mannosidase I genes is regulated by cellular stress and developmental cues. The activity is part of the calnexin/calreticulin cycle, which monitors protein folding in the ER. Misfolded glycoproteins are targeted for degradation via ERAD, where mannosidase I plays a role in generating a signal for degradation. This quality control ensures that only properly folded proteins proceed through the secretory pathway.
Key Genes Involved in GO:0004571 mannosyl-oligosaccharide 1,2-alpha-mannosidase activity
The following genes encode enzymes with mannosyl-oligosaccharide 1,2-alpha-mannosidase activity or are directly involved in its regulation and function.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MAN1A1 | Human Golgi alpha-1,2-mannosidase IA | N-glycan processing; cancer biomarker |
| MAN1B1 | Human ER alpha-1,2-mannosidase IB | Congenital disorder of glycosylation type IIb |
| MAN1C1 | Human Golgi alpha-1,2-mannosidase IC | Tissue-specific glycosylation |
| MNS1 | Yeast ER alpha-1,2-mannosidase | Model for N-glycan processing |
| MNS2 | Yeast Golgi alpha-1,2-mannosidase | Golgi glycosylation |
| MNS3 | Yeast Golgi alpha-1,2-mannosidase | Golgi glycosylation |
| FMANIB | Aspergillus oryzae 1,2-alpha-mannosidase | Fungal glycan processing; GFP visualization |
| TRE_ALPHA_MAN | Trichoderma reesei alpha-1,2-mannosidase | Structural studies of substrate cleavage |
| AS_MAN | Aspergillus saitoi 1,2-alpha-D-mannosidase | Catalytic residue identification |
| TC_MAN | Trypanosoma cruzi neutral alpha(1,2)-mannosidase | Parasite glycosylation |
| HEN_MAN | Hen oviduct alpha 1,2-mannosidase | Vertebrate enzyme characterization |
| BAC_MAN | Bacillus sp. 1,2-alpha-D-mannosidase | Bacterial enzyme mode of action |
| AO_MAN | Aspergillus oryzae 1,2-alpha-mannosidase | Overproduction and industrial use |
| EDEM1 | ER degradation-enhancing alpha-mannosidase-like protein | ERAD of misfolded proteins |
| EDEM2 | ER degradation-enhancing alpha-mannosidase-like protein | ERAD |
| EDEM3 | ER degradation-enhancing alpha-mannosidase-like protein | ERAD |
| GCS1 | Golgi alpha-1,2-mannosidase | Yeast glycosylation |
| MNL1 | Yeast mannosidase-like protein | ER quality control |
How Is mannosyl-oligosaccharide 1,2-alpha-mannosidase activity Regulated?
Mannosyl-oligosaccharide 1,2-alpha-mannosidase activity is regulated at multiple levels. Transcription of mannosidase genes is induced by ER stress via the unfolded protein response (UPR) pathway. In yeast, the UPR sensor Ire1p splices HAC1 mRNA, leading to increased expression of folding and processing enzymes, including Mns1p. Additionally, the activity is modulated by pH and calcium levels in the ER and Golgi, which affect enzyme conformation and substrate binding. Post-translational modifications, such as N-glycosylation of the enzyme itself, can influence its stability and activity.
mannosyl-oligosaccharide 1,2-alpha-mannosidase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| MAN1B1 | Congenital disorder of glycosylation type IIb | Knockout HEK293 cells; patient-derived fibroblasts |
| MAN1A1 | Cancer progression and metastasis | Knockdown in cancer cell lines; xenograft models |
| MNS1 | Fungal cell wall integrity | Yeast knockout and complementation |
| FMANIB | Aspergillus infection | Fungal knockout; GFP-tagged knock-in |
| TC_MAN | Chagas disease | Trypanosoma cruzi knockout; macrophage infection |
Congenital Disorders of Glycosylation (CDG)
Mutations in MAN1B1 cause a congenital disorder of glycosylation (CDG-IIb), characterized by developmental delay, intellectual disability, and dysmorphic features. This highlights the critical role of alpha-1,2-mannosidase activity in normal development and protein glycosylation.
Cancer
Altered expression of mannosidases, including MAN1A1 and MAN1B1, has been observed in various cancers, where they affect cell adhesion, migration, and metastasis. For example, downregulation of MAN1A1 is associated with poor prognosis in some cancers, suggesting a tumor suppressor role.
Infectious Diseases
Fungal mannosidases are essential for cell wall integrity and virulence, making them potential targets for antifungal drugs [1,8]. In Trypanosoma cruzi, the causative agent of Chagas disease, alpha-1,2-mannosidase activity is involved in glycoprotein processing and host cell invasion.
From mannosyl-oligosaccharide 1,2-alpha-mannosidase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of MAN1B1 in ER quality control? | CRISPR knockout of MAN1B1 in HEK293 cells |
| How does a catalytic point mutation affect enzyme activity? | Point mutation (e.g., E411Q) knock-in in Aspergillus saitoi |
| Where is the enzyme localized in living cells? | GFP-tagged knock-in of FMANIB in Aspergillus oryzae |
| Does overexpression of MAN1A1 alter glycosylation? | Overexpression of MAN1A1 in CHO cells |
| What is the substrate specificity of Trichoderma reesei mannosidase? | Site-directed mutagenesis and X-ray crystallography |
| Can mannosidase inhibitors block fungal growth? | Knockout of MNS1 in Candida albicans |
How to Study the mannosyl-oligosaccharide 1,2-alpha-mannosidase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluorogenic substrate assay | Enzyme activity | Kinetic studies and inhibitor screening |
| HPLC oligosaccharide analysis | Substrate cleavage profile | Characterization of enzyme specificity |
| X-ray crystallography | Three-dimensional structure | Active site mapping |
| Site-directed mutagenesis | Catalytic residue function | Mechanistic studies |
| Mass spectrometry | N-glycan composition | Glycosylation profiling in disease |
| Lectin blotting | Glycan epitopes | Detection of glycosylation changes |
| CRISPR knockout screening | Gene function in glycosylation | Identification of novel regulators |
| GFP-tagged knock-in | Subcellular localization | Live-cell imaging |
Enzymatic Activity Assays
Mannosyl-oligosaccharide 1,2-alpha-mannosidase activity is typically measured using fluorogenic or chromogenic substrates, such as 4-methylumbelliferyl-alpha-D-mannopyranoside, or by HPLC analysis of oligosaccharide trimming. These assays allow kinetic characterization and inhibitor screening.
Structural Biology
X-ray crystallography and cryo-EM have been used to determine the structure of alpha-1,2-mannosidases, revealing the active site architecture and substrate binding. Site-directed mutagenesis combined with structural data identifies catalytic residues.
Glycan Analysis
Mass spectrometry (MALDI-TOF, LC-ESI-MS) and lectin blotting are used to profile N-glycans and assess the impact of mannosidase activity on glycosylation patterns. These methods are essential for studying CDG and cancer-associated glycan changes.
CRISPR Screening
Genome-wide CRISPR knockout screens can identify genes that modulate mannosidase activity or glycosylation pathways, using lectin-based selection or fluorescent reporters. This approach uncovers novel regulators and potential drug targets.
How CRISPR Can Be Used to Study GO:0004571 mannosyl-oligosaccharide 1,2-alpha-mannosidase activity
Knockout
CRISPR knockout of mannosidase genes (e.g., MAN1B1, MNS1) enables loss-of-function studies to determine their role in glycosylation, ER stress, and disease. Knockout cell lines can be used to assess changes in glycan structures and protein folding.
Point Mutation
Introducing specific point mutations (e.g., catalytic glutamate to glutamine) via CRISPR base editing or homology-directed repair allows precise dissection of enzyme mechanism and substrate specificity.
Knock-in
Knock-in of tagged versions (e.g., GFP, FLAG) of mannosidase genes facilitates live-cell imaging, immunoprecipitation, and proteomic studies to track localization and interactions.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of mannosidase genes can be used to study gain-of-function effects on glycosylation and cellular phenotypes, such as cancer cell migration.
How EDITGENE Supports mannosyl-oligosaccharide 1,2-alpha-mannosidase activity Research
Researchers studying mannosyl-oligosaccharide 1,2-alpha-mannosidase activity-related genes often need to determine whether a candidate gene is causally involved in glycosylation, protein quality control, or disease. EDITGENE provides a comprehensive suite of CRISPR services to accelerate this research, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for mannosyl-oligosaccharide 1,2-alpha-mannosidase activity research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| MAN1A1 Knockout HEK293 Cell Line | EDJ-KQ5174 | Human | 4121 | Details Get a Quote |
| EDEM1 Knockout HEK293 Cell Line | EDJ-KQ6695 | Human | 9695 | Details Get a Quote |
| MAN1A2 Knockout HEK293 Cell Line | EDJ-KQ7210 | Human | 10905 | Details Get a Quote |
| MAN1B1 Knockout HEK293 Cell Line | EDJ-KQ7351 | Human | 11253 | Details Get a Quote |
| EDEM3 Knockout HEK293 Cell Line | EDJ-KQ9507 | Human | 80267 | Details Get a Quote |
| EDEM2 Knockout HEK293 Cell Line | EDJ-KQ12476 | Human | 55741 | Details Get a Quote |
| MAN1C1 Knockout HEK293 Cell Line | EDJ-KQ14189 | Human | 57134 | Details Get a Quote |
| MAN1A1 Knockout HCT 116 Cell Line | EDJ-KQ28158 | Human | 4121 | Details Get a Quote |
| MAN1A1 Knockout HeLa Cell Line | EDJ-KQ28159 | Human | 4121 | Details Get a Quote |
| EDEM1 Knockout A-549 Cell Line | EDJ-KQ31050 | Human | 9695 | Details Get a Quote |
| EDEM1 Knockout HCT 116 Cell Line | EDJ-KQ31051 | Human | 9695 | Details Get a Quote |
| EDEM1 Knockout HeLa Cell Line | EDJ-KQ31052 | Human | 9695 | Details Get a Quote |
| MAN1B1 Knockout A-549 Cell Line | EDJ-KQ31084 | Human | 11253 | Details Get a Quote |
| MAN1A2 Knockout A-549 Cell Line | EDJ-KQ32155 | Human | 10905 | Details Get a Quote |
| MAN1A2 Knockout HCT 116 Cell Line | EDJ-KQ32156 | Human | 10905 | Details Get a Quote |
Displaying Records 1 To 15 Of 28 Records
Frequently Asked Questions About mannosyl-oligosaccharide 1,2-alpha-mannosidase activity
What is mannosyl-oligosaccharide 1,2-alpha-mannosidase activity?
It is an enzymatic activity (GO:0004571) that removes terminal alpha-1,2-linked mannose residues from oligo-mannose oligosaccharides, a key step in N-glycan processing.
What genes are involved in mannosyl-oligosaccharide 1,2-alpha-mannosidase activity?
Key genes include MAN1A1, MAN1B1, MAN1C1 in humans, MNS1, MNS2, MNS3 in yeast, and FMANIB in Aspergillus [3,8].
What diseases are associated with mannosidase I deficiency?
Mutations in MAN1B1 cause congenital disorder of glycosylation type IIb, and altered expression is linked to cancer.
How is mannosyl-oligosaccharide 1,2-alpha-mannosidase activity measured?
It is measured using fluorogenic substrates, HPLC, or mass spectrometry to detect mannose trimming.
What is the role of mannosidase I in the ER?
It trims mannose residues from N-glycans, aiding protein folding and quality control in the endoplasmic reticulum.
Can CRISPR be used to study mannosidase genes?
Yes, CRISPR knockout, point mutation, and knock-in models enable precise functional studies of mannosidase genes [3,6].
What are the substrates of alpha-1,2-mannosidase?
Oligo-mannose oligosaccharides such as Man9GlcNAc2 with terminal alpha-1,2-linked mannose residues [3,4].
Is mannosidase I a calcium-dependent enzyme?
Some mannosidases require calcium, while others are calcium-independent, depending on the source organism [4,6].
What is the difference between MAN1A1 and MAN1B1?
MAN1A1 is a Golgi enzyme, while MAN1B1 localizes to the ER and is associated with CDG-IIb.
How does mannosidase activity affect cancer?
Altered mannosidase expression affects cell adhesion, migration, and metastasis, making it a potential cancer biomarker.
Conclusion
Mannosyl-oligosaccharide 1,2-alpha-mannosidase activity (GO:0004571) is a cornerstone of N-glycan processing, with critical roles in protein folding, cellular quality control, and human disease. Its study spans enzymology, structural biology, and glycobiology, and is now accelerated by CRISPR-based genome editing. Understanding this activity offers insights into congenital disorders, cancer, and infectious diseases, and provides opportunities for therapeutic intervention. EDITGENE's suite of CRISPR services empowers researchers to dissect the functions of mannosidase genes with precision and efficiency.
References
- 1. Yoshida T et al.. 1998. Overproduction of 1,2-alpha-mannosidase, a glycochain processing enzyme, by Aspergillus oryzae.. Biosci Biotechnol Biochem 62(2):309-15 PMID: 9532788
- 2. Maruyama Y et al.. 1994. A 1,2-alpha-D-mannosidase from a Bacillus sp.: purification, characterization, and mode of action.. Carbohydr Res 251:89-98 PMID: 8149382
- 3. Herscovics A. 1999. Processing glycosidases of Saccharomyces cerevisiae.. Biochim Biophys Acta 1426(2):275-85 PMID: 9878780
- 4. Van Petegem F et al.. 2001. Trichoderma reesei alpha-1,2-mannosidase: structural basis for the cleavage of four consecutive mannose residues.. J Mol Biol 312(1):157-65 PMID: 11545593
- 5. Hamagashira N et al.. 1996. Purification and characterization of hen oviduct alpha 1,2-mannosidase.. J Biochem 119(5):998-1003 PMID: 8797103
- 6. Tatara Y et al.. 2003. Identification of catalytic residues of Ca2+-independent 1,2-alpha-D-mannosidase from Aspergillus saitoi by site-directed mutagenesis.. J Biol Chem 278(28):25289-94 PMID: 12702721
- 7. Bonay P et al.. 1999. Isolation and purification of a neutral alpha(1,2)-mannosidase from Trypanosoma cruzi.. Glycobiology 9(5):423-33 PMID: 10207175
- 8. Akao T et al.. 2006. Cloning and expression of 1,2-alpha-mannosidase gene (fmanIB) from filamentous fungus Aspergillus oryzae: in vivo visualization of the FmanIBp-GFP fusion protein.. Biosci Biotechnol Biochem 70(2):471-9 PMID: 16495665
