GO:0047290 alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047290 describes the enzymatic activity that adds sialic acid in an alpha-2,6 linkage to the N-acetylgalactosamine residue of the core 1 O-glycan structure NeuAc-alpha-2,3-Gal-beta-1,3-GalNAc-R.
• This activity is catalyzed by members of the ST6GALNAC family of sialyltransferases, which transfer CMP-activated sialic acid to specific acceptor substrates.
• The reaction is essential for the biosynthesis of complex sialylated O-glycans that modulate cell recognition, signaling, and immune interactions.
• The human ST6GALNAC IV gene (hST6GalNAc IV) is transcriptionally regulated by specific promoter elements, indicating tight control of this activity.
• Dysregulation of alpha-2,6-sialylation has been linked to cancer progression, metastasis, and altered immune responses, making this enzyme a potential therapeutic target.
• CRISPR-based knockout, knock-in, and overexpression models are powerful tools to dissect the precise roles of GO:0047290 in health and disease.
Description
GO:0047290, officially named alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity, is a molecular function term in the Gene Ontology that describes a specific sialyltransferase reaction. This activity catalyzes the transfer of N-acetylneuraminic acid (sialic acid) from CMP-N-acetyl-beta-neuraminate to the N-acetylgalactosamine residue of the core 1 O-glycan structure alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-N-acetyl-D-galactosaminyl-R, forming an alpha-2,6 linkage and releasing CMP. The enzyme responsible for this activity belongs to the ST6GALNAC family, with ST6GALNAC IV being a well-characterized human member. This modification is critical for the structural diversity of glycans on cell surfaces and secreted proteins, influencing processes such as cell adhesion, receptor signaling, and immune recognition. Researchers study GO:0047290 to understand how altered sialylation contributes to diseases including cancer and inflammatory disorders.
alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity At A Glance
| GO ID | GO:0047290 |
|---|---|
| GO term | alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity |
| Ontology | molecular_function |
| Synonym | alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide alpha-2,6-sialyltransferase activity; ST6GALNAC activity; NeuAc-alpha-2,3-Gal-beta-1,3-GalNAc-alpha-2,6-sialyltransferase activity |
| Major function | Catalyzes the transfer of sialic acid from CMP-N-acetyl-beta-neuraminate to the N-acetylgalactosamine of core 1 O-glycans, forming an alpha-2,6 linkage. |
| Substrates | alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-N-acetyl-D-galactosaminyl-R and CMP-N-acetyl-beta-neuraminate. |
| Products | alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-[N-acetyl-alpha-neuraminyl-(2->6)]-N-acetyl-D-galactosaminyl-R and CMP. |
| Cofactors | Divalent cations such as Mn2+ are typically required for sialyltransferase activity, though specific requirements may vary. |
| Regulation | Transcription of the human ST6GALNAC IV gene is controlled by regulatory elements in its promoter. |
What Is GO:0047290?
In simple terms, GO:0047290 is the enzyme activity that attaches a sialic acid molecule to a specific sugar (N-acetylgalactosamine) on the core 1 O-glycan, using CMP-sialic acid as the donor. The reaction converts alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-N-acetyl-D-galactosaminyl-R into alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-[N-acetyl-alpha-neuraminyl-(2->6)]-N-acetyl-D-galactosaminyl-R, releasing CMP.
Why Is alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity Important in Cell Biology?
GO:0047290 is important because it governs a key step in the biosynthesis of sialylated O-glycans, which are abundant on cell surface and secreted glycoproteins. These glycans participate in cell-cell communication, immune surveillance, and signal transduction. Aberrant expression of this activity can lead to pathological changes in glycosylation that are associated with cancer, metastasis, and inflammatory diseases. Understanding the regulation and function of this enzyme provides insights into disease mechanisms and may guide the development of glycan-based therapeutics.
• Modulates cell surface sialylation, affecting cell recognition and adhesion.
• Plays a role in the biosynthesis of core 1 O-glycans, which are common on mucins and other glycoproteins.
• Altered expression is observed in various cancers and correlates with tumor progression.
• Influences immune cell interactions and may impact immunotherapy responses.
• Provides a target for glycoengineering and therapeutic intervention.
• Its transcriptional regulation by promoter elements highlights its potential as a biomarker.
• Contributes to the diversity of the glycome, which is critical for normal development and physiology.
• Enables researchers to study structure-function relationships of sialyltransferases.
• May be involved in pathogen recognition and host-microbe interactions.
• Offers a model system to investigate the specificity of glycosyltransferases.
What Happens During alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity?
Substrate Recognition and Binding
In simple terms: The enzyme first grabs the sugar chain and the activated sialic acid donor.
The enzyme recognizes the acceptor substrate alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-N-acetyl-D-galactosaminyl-R and the donor CMP-N-acetyl-beta-neuraminate. Binding involves specific interactions with the terminal sialic acid and the GalNAc residue, ensuring regioselectivity for the alpha-2,6 linkage.
Catalytic Transfer of Sialic Acid
In simple terms: The enzyme snips off sialic acid from CMP and attaches it to the sugar chain.
The catalytic mechanism involves the transfer of the sialic acid moiety from CMP-N-acetyl-beta-neuraminate to the 6-hydroxyl group of the N-acetylgalactosamine residue. This reaction proceeds via a conserved sialyltransferase fold, with a likely oxocarbenium ion-like transition state. The byproduct CMP is released.
Product Formation and Release
In simple terms: The newly modified sugar chain is released, ready to function on the cell surface.
The product alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-[N-acetyl-alpha-neuraminyl-(2->6)]-N-acetyl-D-galactosaminyl-R is released from the active site. This doubly sialylated core 1 structure can then be further elongated or presented on glycoproteins and glycolipids.
Role of Cofactors and Metal Ions
In simple terms: Metal ions help the enzyme work properly.
Like many sialyltransferases, this activity may require divalent metal ions such as Mn2+ for optimal catalysis. These ions help stabilize the donor and facilitate the transfer reaction. However, the exact metal dependency can vary among family members.
Regulation of Enzyme Activity
In simple terms: The amount and activity of the enzyme are controlled by the cell.
The activity is regulated at multiple levels, including transcriptional control of the ST6GALNAC IV gene by promoter elements. Post-translational modifications and subcellular localization may also influence enzyme function.
Key Genes Involved in GO:0047290 alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity
The following genes and proteins are directly or indirectly associated with GO:0047290, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ST6GALNAC4 | Encodes alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase, the enzyme responsible for GO:0047290 | Key target for studying O-glycan sialylation and cancer |
| ST6GALNAC1 | Another sialyltransferase with related activity, may compensate or overlap in function | Potential redundancy in sialylation pathways |
| ST6GALNAC2 | Sialyltransferase that can modify similar substrates | Used in comparative studies of sialyltransferase specificity |
| ST6GALNAC3 | Member of the ST6GALNAC family, may share substrate specificity | Relevant for understanding family evolution and function |
| ST6GALNAC5 | Sialyltransferase involved in ganglioside synthesis | Context for substrate competition |
| ST6GALNAC6 | Sialyltransferase with broad expression | Potential functional overlap |
| ST3GAL1 | Adds sialic acid in alpha-2,3 linkage to galactose, upstream of GO:0047290 | Generates the substrate for ST6GALNAC enzymes |
| ST3GAL2 | Similar to ST3GAL1, produces alpha-2,3-sialylated glycans | Upstream enzyme in the pathway |
| C1GALT1 | Core 1 synthase, generates the T antigen (Gal-beta-1,3-GalNAc) | Provides the initial acceptor for sialylation |
| GALNT1 | Initiates O-glycosylation by adding GalNAc to serine/threonine | Upstream of core 1 formation |
| B3GALT1 | Beta-1,3-galactosyltransferase, may contribute to core 1 extension | Modifies glycan structures |
| SLC35A1 | CMP-sialic acid transporter, supplies donor to Golgi | Affects substrate availability |
| GNE | UDP-GlcNAc 2-epimerase/ManNAc kinase, regulates sialic acid biosynthesis | Influences donor pool |
| NANS | Sialic acid synthase, produces Neu5Ac | Affects sialylation capacity |
| CMAS | CMP-sialic acid synthetase, activates sialic acid | Provides CMP-Neu5Ac donor |
| B4GALT1 | Beta-1,4-galactosyltransferase, can modify N-glycans and O-glycans | May compete for substrates |
| FUT8 | Fucosyltransferase, adds fucose to N-glycans | Cross-talk with sialylation pathways |
| MGAT5 | N-acetylglucosaminyltransferase V, involved in N-glycan branching | Indirectly affects glycan complexity |
How Is alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity Regulated?
The expression of the human ST6GALNAC IV gene, which encodes the enzyme responsible for GO:0047290, is regulated by specific promoter elements. Kang et al. (2004) identified regulatory elements involved in the transcription of hST6GalNAc IV, indicating that its expression is tightly controlled at the transcriptional level. This regulation may respond to developmental cues, tissue-specific factors, and pathological conditions. Additionally, the enzyme's activity can be modulated by the availability of donor substrate CMP-sialic acid and acceptor glycans, as well as by post-translational modifications and Golgi localization.
alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ST6GALNAC4 | Cancer progression and metastasis | Knockout and overexpression in cancer cell lines |
| ST6GALNAC4 | Altered immune cell recognition | Mouse models with conditional knockout |
| ST6GALNAC1 | Gastric cancer and other malignancies | CRISPR knockout in organoids |
| ST3GAL1 | Upstream of GO:0047290, cancer and inflammation | Point mutations to alter substrate specificity |
| C1GALT1 | Tn syndrome and cancer | Knock-in of disease-associated variants |
Cancer and Metastasis
Altered sialylation, including changes in alpha-2,6-sialyltransferase activity, is frequently observed in cancer. Overexpression of ST6GALNAC family members can lead to increased sialylation of tumor cell surface glycans, which promotes cell migration, invasion, and immune evasion. The specific activity GO:0047290 may contribute to the synthesis of tumor-associated carbohydrate antigens, making it a potential target for cancer therapy.
Inflammatory and Immune Disorders
Sialylated O-glycans play roles in immune cell trafficking and inflammation. Dysregulation of GO:0047290 could affect the glycosylation of adhesion molecules and cytokines, influencing immune responses. However, direct evidence linking this specific activity to inflammatory diseases is still emerging.
Neurological and Developmental Disorders
Sialylation is critical for brain development and function. Although the specific role of GO:0047290 in neurological disorders is not well defined, other sialyltransferases have been implicated in conditions such as schizophrenia and muscular dystrophy. Further research is needed to establish any direct connection.
From alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of ST6GALNAC4 in cancer cell migration? | CRISPR knockout in MDA-MB-231 cells |
| How does alpha-2,6-sialylation affect immune cell activation? | Conditional knockout in mouse T cells |
| Can a point mutation alter substrate specificity? | Knock-in of catalytic domain mutations |
| What is the effect of overexpression on glycan profile? | Doxycycline-inducible overexpression in HEK293 |
| How is ST6GALNAC4 transcription regulated? | Promoter-reporter knock-in in stem cells |
| What proteins interact with ST6GALNAC4? | Endogenous tagging with FLAG or HA |
How to Study the alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Mass spectrometry | Glycan structures and sialylation levels | Global glycomic profiling |
| Lectin flow cytometry | Cell surface alpha-2,6-sialic acid | Phenotypic screening |
| Sialyltransferase assay | Enzymatic activity | Kinetic characterization |
| Luciferase reporter | Promoter activity | Transcriptional regulation studies |
| CRISPR screening | Gene essentiality and modifiers | Identifying synthetic lethal partners |
| RNA-seq | Gene expression changes | Pathway analysis |
| Proteomics | Protein interactions and modifications | Identifying binding partners |
Glycan Profiling by Mass Spectrometry
Mass spectrometry-based glycomics can directly detect the products of GO:0047290, such as the doubly sialylated core 1 structure. This method provides structural details and can quantify changes in sialylation upon genetic manipulation.
Lectin-Based Flow Cytometry
Lectins such as Sambucus nigra agglutinin (SNA) specifically recognize alpha-2,6-linked sialic acid. Flow cytometry with fluorescently labeled lectins can assess cell surface sialylation levels in knockout or overexpression models.
Enzymatic Activity Assays
In vitro sialyltransferase assays using fluorescently labeled acceptor substrates and CMP-sialic acid can measure the specific activity of ST6GALNAC4. These assays are useful for kinetic studies and inhibitor screening.
Transcriptional Reporter Assays
To study regulation, promoter regions of ST6GALNAC4 can be cloned upstream of a luciferase reporter. This allows identification of regulatory elements and transcription factors controlling GO:0047290 expression.
How CRISPR Can Be Used to Study GO:0047290 alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity
Knockout
CRISPR knockout of ST6GALNAC4 can completely abolish GO:0047290 activity, allowing researchers to study its loss-of-function phenotypes. This is particularly useful for assessing the enzyme's role in cancer cell proliferation, migration, and glycan remodeling.
Point Mutation
Introducing point mutations in the catalytic domain of ST6GALNAC4 can help identify essential residues for substrate binding and catalysis. Such mutants can be used to dissect the enzymatic mechanism and to create separation-of-function alleles.
Knock-in
Knock-in of epitope tags (e.g., FLAG, HA) at the endogenous ST6GALNAC4 locus enables visualization and immunoprecipitation of the enzyme in its native context. This approach facilitates studies of localization, trafficking, and interactome.
Overexpression
Overexpression of ST6GALNAC4 using lentiviral or inducible systems can amplify GO:0047290 activity, leading to increased alpha-2,6-sialylation. This is valuable for gain-of-function studies and for producing sialylated glycoproteins for therapeutic applications.
How EDITGENE Supports alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity Research
Researchers studying alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in a specific phenotype. EDITGENE provides a comprehensive suite of CRISPR services to accelerate this discovery process, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity research.
Frequently Asked Questions About alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity
What is GO:0047290?
GO:0047290 is a Gene Ontology molecular function term for the enzyme activity that transfers sialic acid to the N-acetylgalactosamine of core 1 O-glycans, forming an alpha-2,6 linkage.
What genes are involved in alpha-N-acetylneuraminyl-2,3-beta-galactosyl-1,3-N-acetyl-galactosaminide 6-alpha-sialyltransferase activity?
The primary gene is ST6GALNAC4, which encodes the enzyme hST6GalNAc IV. Other ST6GALNAC family members may have related activities.
What is the function of ST6GALNAC4?
ST6GALNAC4 catalyzes the alpha-2,6-sialylation of core 1 O-glycans, contributing to cell surface glycan diversity and affecting cell signaling and adhesion.
How is GO:0047290 regulated?
It is regulated transcriptionally by promoter elements in the ST6GALNAC4 gene, as well as by substrate availability and post-translational mechanisms.
What diseases are associated with alpha-2,6-sialyltransferase activity?
Altered activity has been linked to cancer progression, metastasis, and immune disorders, though direct causality for GO:0047290 requires further study.
What methods are used to study GO:0047290?
Common methods include glycan profiling by mass spectrometry, lectin-based flow cytometry, enzymatic activity assays, and CRISPR-based genetic models.
Can CRISPR be used to study GO:0047290?
Yes, CRISPR knockout, knock-in, and overexpression models are powerful tools to dissect the function of ST6GALNAC4 and its role in disease.
What is the substrate for ST6GALNAC4?
The acceptor substrate is alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-N-acetyl-D-galactosaminyl-R, and the donor is CMP-N-acetyl-beta-neuraminate.
Is ST6GALNAC4 the only enzyme with this activity?
While ST6GALNAC4 is a major enzyme for this activity, other ST6GALNAC family members may exhibit overlapping substrate specificity.
How can I model GO:0047290 in the lab?
You can use CRISPR knockout or overexpression in cell lines, or generate knock-in mice with tagged ST6GALNAC4 for in vivo studies.
Conclusion
GO:0047290 represents a specific and biologically important sialyltransferase activity that modifies core 1 O-glycans. Its product, the alpha-2,6-sialylated core 1 structure, plays roles in cell recognition, signaling, and disease. Understanding the regulation and function of the enzyme ST6GALNAC4, which carries out this activity, is essential for uncovering mechanisms of cancer and immune disorders. CRISPR-based models offer robust tools to study this activity in detail, and EDITGENE provides comprehensive services to support such research.
References
- 1. Baubichon-Cortay H et al.. 1989. Different reactivity of two brain sialyltransferases towards sulfhydryl reagents. Evidence for a thiol group involved in the nucleotide-sugar binding site of the NeuAc alpha 2-3Gal beta 1-3GalNAc alpha(2-6)sialyltransferase.. Glycoconj J 6(1):115-27 PMID: 2485232
- 2. Kang NY et al.. 2004. Regulatory elements involved in transcription of the human NeuAcalpha2,3Galbeta1,3GalNAcalpha2,6-sialyltransferase (hST6GalNAc IV) gene.. Mol Cells 18(2):157-62 PMID: 15528990
