GO:0047402 protein-glucosylgalactosylhydroxylysine glucosidase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047402 describes the enzymatic activity that removes glucose from a specific disaccharide (glucosylgalactose) attached to hydroxylysine residues in collagen and collagen-like proteins.
• The reaction catalyzed is: H2O + protein alpha-D-glucosyl-1,2-beta-D-galactosyl-L-hydroxylysine = protein beta-D-galactosyl-L-hydroxylysine + beta-D-glucose.
• This activity is essential for the proper processing of collagen glycosylation, influencing collagen cross-linking, stability, and extracellular matrix remodeling.
• The human enzyme is a glucosidase that specifically hydrolyzes the alpha-1,2-glucosidic bond, and three crucial carboxyl residues (Asp, Glu, Glu) form its catalytic site.
• Dysregulation of this activity has been linked to connective tissue disorders and fibrosis, making it a potential therapeutic target.
• CRISPR-based knockout, point mutation, and knock-in models are powerful tools to dissect the physiological roles of this enzyme in health and disease.
Description
Protein-glucosylgalactosylhydroxylysine glucosidase (EC 3.2.1.107) is a molecular function defined by the Gene Ontology term GO:0047402. It catalyzes the hydrolysis of glucose from alpha-D-glucosyl-(1->2)-beta-D-galactosyl disaccharide units that are linked to hydroxylysine residues of collagen and collagen-like proteins. This activity is critical for the stepwise remodeling of collagen glycosylation, a post-translational modification that affects collagen fibril assembly, cross-linking, and interactions with other extracellular matrix components. Researchers study this enzyme to understand connective tissue biology, fibrosis, and rare genetic disorders affecting collagen metabolism. The human enzyme has been cloned and characterized, revealing that three carboxyl residues are essential for catalysis. This article provides a comprehensive overview of GO:0047402, including its definition, mechanism, associated genes, disease relevance, and modern research methods such as CRISPR-based editing.
protein-glucosylgalactosylhydroxylysine glucosidase activity At A Glance
| GO ID | GO:0047402 |
|---|---|
| GO term | protein-glucosylgalactosylhydroxylysine glucosidase activity |
| Ontology | molecular_function |
| Synonym | 2-O-alpha-D-glucopyranosyl-5-O-alpha-D-galactopyranosylhydroxy-L-lysine glucohydrolase activity; protein-alpha-D-glucosyl-1,2-beta-D-galactosyl-L-hydroxylysine glucohydrolase activity |
| Definition | Catalysis of the reaction: H2O + protein alpha-D-glucosyl-1,2-beta-D-galactosyl-L-hydroxylysine = protein beta-D-galactosyl-L-hydroxylysine + beta-D-glucose. The enzyme specifically hydrolyzes glucose from alpha-D-glucosyl- (1->2)-beta-D-galactosyl disaccharide units that are linked to hydroxylysine residues of collagen and collagen-like proteins. |
| Major function | Removal of glucose from glucosylgalactosylhydroxylysine in collagen and collagen-like proteins |
| Catalytic residues | Three crucial carboxyl residues (aspartate and glutamate) identified by site-directed mutagenesis |
| Substrate | Protein alpha-D-glucosyl-1,2-beta-D-galactosyl-L-hydroxylysine |
| Product | Protein beta-D-galactosyl-L-hydroxylysine and beta-D-glucose |
What Is GO:0047402?
GO:0047402, protein-glucosylgalactosylhydroxylysine glucosidase activity, is a molecular function that enables the hydrolysis of a specific glycosidic bond. Specifically, it removes glucose from the disaccharide alpha-D-glucosyl-1,2-beta-D-galactose that is attached to hydroxylysine residues in collagen and collagen-like proteins. The reaction yields beta-D-glucose and a protein beta-D-galactosyl-L-hydroxylysine intermediate. This activity is also known as 2-O-alpha-D-glucopyranosyl-5-O-alpha-D-galactopyranosylhydroxy-L-lysine glucohydrolase activity or protein-alpha-D-glucosyl-1,2-beta-D-galactosyl-L-hydroxylysine glucohydrolase activity.
Why Is protein-glucosylgalactosylhydroxylysine glucosidase activity Important in Cell Biology?
GO:0047402 is important because it governs a key step in collagen glycosylation, a post-translational modification that influences collagen folding, secretion, and fibril formation. Proper processing of glucosylgalactosylhydroxylysine is essential for the mechanical stability of connective tissues, and defects in this pathway can lead to connective tissue disorders, fibrosis, and impaired wound healing. Understanding this activity at the molecular level provides insights into extracellular matrix biology and offers potential targets for therapeutic intervention in diseases characterized by abnormal collagen deposition.
• Regulates collagen glycosylation, affecting collagen cross-linking and stability.
• Influences extracellular matrix remodeling and tissue homeostasis.
• Implicated in connective tissue disorders such as Ehlers-Danlos syndrome and fibrosis.
• Provides a model for studying glycoside hydrolase mechanism and specificity.
• Potential biomarker for diseases with altered collagen metabolism.
• Target for antifibrotic therapies aimed at modulating collagen processing.
• Essential for normal bone and skin development.
• Contributes to the quality control of collagen in the endoplasmic reticulum.
• Its catalytic residues are conserved, offering insights into enzyme evolution.
• CRISPR screens can identify regulators of this activity in human cells.
What Happens During protein-glucosylgalactosylhydroxylysine glucosidase activity?
Substrate Recognition and Binding
In simple terms: The enzyme finds and grabs onto its target: a sugar-modified collagen protein.
The enzyme recognizes collagen or collagen-like proteins that carry a specific disaccharide, alpha-D-glucosyl-1,2-beta-D-galactose, attached to hydroxylysine residues. This recognition is mediated by the enzyme's active site, which complements the shape and charge of the substrate. The three crucial carboxyl residues (aspartate and glutamate) identified by site-directed mutagenesis are likely involved in binding and positioning the substrate for catalysis.
Catalytic Hydrolysis
In simple terms: The enzyme cuts the bond between glucose and galactose, releasing glucose.
Once bound, the enzyme catalyzes the hydrolysis of the alpha-1,2-glucosidic bond between glucose and galactose. This reaction uses a water molecule to cleave the bond, resulting in the release of beta-D-glucose and the formation of protein beta-D-galactosyl-L-hydroxylysine. The catalytic mechanism likely involves a glycosyl-enzyme intermediate or a direct displacement mechanism, with the carboxyl residues acting as nucleophile and acid/base catalysts.
Product Release and Enzyme Turnover
In simple terms: After cutting, the enzyme lets go of the products and is ready to act again.
Following hydrolysis, the products (glucose and the galactosyl-hydroxylysine protein) are released from the active site. The enzyme then undergoes conformational changes to reset for another round of catalysis. This turnover is essential for the processive or distributive action of the enzyme on multiple substrate molecules within the collagen triple helix or in the endoplasmic reticulum.
Role in Collagen Maturation
In simple terms: This step helps collagen become fully mature and functional.
The removal of glucose is a late step in collagen glycosylation, after galactose has been added to hydroxylysine. The resulting galactosyl-hydroxylysine can then participate in cross-linking reactions or interact with other matrix components. This processing is crucial for the proper assembly and stability of collagen fibrils, and defects can lead to connective tissue abnormalities.
Key Genes Involved in GO:0047402 protein-glucosylgalactosylhydroxylysine glucosidase activity
The following genes and proteins are directly or indirectly involved in protein-glucosylgalactosylhydroxylysine glucosidase activity, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| GAL3ST1 | Galactosyltransferase that adds galactose to hydroxylysine | Upstream of glucosidase in collagen glycosylation |
| GLT25D1 | Glucosyltransferase that adds glucose to galactosylhydroxylysine | Creates the substrate for GO:0047402 |
| GLT25D2 | Glucosyltransferase that adds glucose to galactosylhydroxylysine | Creates the substrate for GO:0047402 |
| COL1A1 | Major collagen type I alpha chain | Contains hydroxylysine glycosylation sites |
| COL1A2 | Major collagen type I alpha chain | Contains hydroxylysine glycosylation sites |
| COL3A1 | Collagen type III alpha chain | Substrate for glycosylation and glucosidase |
| COL4A1 | Collagen type IV alpha chain | Basement membrane collagen with glycosylation |
| COL5A1 | Collagen type V alpha chain | Regulates collagen fibril assembly |
| LYSYL_HYDROXYLASE | Enzyme that hydroxylates lysine in collagen | Essential for creating hydroxylysine |
| PLOD1 | Lysyl hydroxylase 1 | Hydroxylates lysine in collagen |
| PLOD2 | Lysyl hydroxylase 2 | Hydroxylates lysine in collagen |
| PLOD3 | Lysyl hydroxylase 3 | Hydroxylates lysine in collagen |
| P4HB | Protein disulfide isomerase | Assists in collagen folding |
| HSP47 | Collagen-specific chaperone | Facilitates collagen folding and transport |
| MAN1B1 | Alpha-1,2-mannosidase | N-glycan processing, not directly related |
| GANAB | Glucosidase II alpha subunit | N-glycan processing, not directly related |
| PRKCSH | Glucosidase II beta subunit | N-glycan processing, not directly related |
How Is protein-glucosylgalactosylhydroxylysine glucosidase activity Regulated?
The activity of protein-glucosylgalactosylhydroxylysine glucosidase is likely regulated at multiple levels, including enzyme expression, post-translational modifications, and substrate availability. However, specific regulatory mechanisms have not been fully elucidated. The enzyme's activity may be influenced by the glycosylation state of collagen and the availability of its substrate, which is generated by glucosyltransferases such as GLT25D1 and GLT25D2. Further research is needed to identify upstream signaling pathways and regulatory proteins.
protein-glucosylgalactosylhydroxylysine glucosidase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| COL1A1 | Osteogenesis imperfecta | Knock-in mouse with Gly substitution |
| COL3A1 | Ehlers-Danlos syndrome type IV | Knockout mouse |
| PLOD2 | Bruck syndrome | Point mutation knock-in |
| GLT25D1 | Connective tissue disorder | CRISPR knockout in fibroblasts |
| GAL3ST1 | Leukodystrophy | Knockout zebrafish |
Connective Tissue Disorders
Defects in collagen glycosylation, including the step catalyzed by GO:0047402, have been associated with connective tissue disorders such as Ehlers-Danlos syndrome and osteogenesis imperfecta. Mutations in genes encoding collagen or glycosylation enzymes can lead to abnormal collagen cross-linking and weakened connective tissues.
Fibrosis
Excessive collagen deposition is a hallmark of fibrosis. Altered activity of protein-glucosylgalactosylhydroxylysine glucosidase may contribute to the accumulation of improperly processed collagen, exacerbating fibrotic pathology in organs such as liver, lung, and kidney.
Cancer
Collagen remodeling is critical for tumor progression and metastasis. Changes in collagen glycosylation, including the glucosidase step, can affect tumor cell adhesion, migration, and invasion. Targeting this activity may offer novel therapeutic strategies in oncology.
From protein-glucosylgalactosylhydroxylysine glucosidase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the catalytic mechanism? | Point mutation of catalytic residues (D, E, E) in recombinant enzyme |
| What is the role in collagen cross-linking? | Knockout of the glucosidase gene in mouse fibroblasts |
| How does it affect fibrosis? | Overexpression in hepatic stellate cells |
| What are its interacting partners? | Tagged knock-in for affinity purification |
| Is it essential for development? | Conditional knockout in mice |
| Can it be targeted therapeutically? | CRISPR library screening for small molecule inhibitors |
How to Study the protein-glucosylgalactosylhydroxylysine glucosidase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzymatic assay | Glucosidase activity | Kinetic analysis of wild-type and mutant enzymes |
| CRISPR knockout | Loss-of-function phenotype | Studying collagen processing in fibroblasts |
| Mass spectrometry | Collagen glycosylation profile | Identifying substrate specificity |
| Immunofluorescence | Collagen fibril morphology | Assessing extracellular matrix organization |
| Western blot | Protein expression levels | Validating knockout or overexpression |
| qRT-PCR | mRNA expression | Measuring transcriptional regulation |
| CRISPR library screening | Gene essentiality | Identifying synthetic lethal interactions |
Enzymatic Assays
In vitro enzymatic assays using synthetic substrates or purified collagen can measure the glucosidase activity directly. These assays typically monitor the release of glucose using colorimetric or fluorogenic substrates. Site-directed mutagenesis of the catalytic residues can confirm their essential role.
CRISPR-Cas9 Knockout
CRISPR-Cas9 can be used to generate knockout cell lines or animal models to study the loss-of-function phenotype of the glucosidase. This approach helps determine its role in collagen processing, extracellular matrix organization, and disease development.
Proteomics and Glycomics
Mass spectrometry-based proteomics and glycomics can analyze the glycosylation state of collagen in cells with altered glucosidase activity. This reveals the specific substrate sites and downstream effects on collagen structure and function.
Imaging and Histology
Immunofluorescence and electron microscopy can visualize collagen fibril morphology and organization in tissues or cells lacking the glucosidase. Histological staining for collagen cross-links can further assess functional consequences.
How CRISPR Can Be Used to Study GO:0047402 protein-glucosylgalactosylhydroxylysine glucosidase activity
Knockout
CRISPR-Cas9 knockout of the gene encoding protein-glucosylgalactosylhydroxylysine glucosidase can completely abolish its activity, allowing researchers to study the consequences for collagen glycosylation, fibril assembly, and tissue homeostasis. Knockout models are invaluable for identifying the physiological substrates and pathways affected.
Point Mutation
Introducing point mutations in the catalytic residues (e.g., aspartate and glutamate) via CRISPR base editing or homology-directed repair can create catalytically dead or hypomorphic alleles. These models help dissect the enzymatic versus non-enzymatic functions of the protein.
Knock-in
Knock-in of a tagged version of the enzyme (e.g., FLAG or GFP) enables affinity purification, live-cell imaging, and proteomic analysis of interacting partners. This approach provides insights into the enzyme's localization and regulation in vivo.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression can increase the levels of the glucosidase, allowing researchers to study gain-of-function effects on collagen processing and to test whether excess activity contributes to fibrosis or cancer progression.
How EDITGENE Supports protein-glucosylgalactosylhydroxylysine glucosidase activity Research
Researchers studying protein-glucosylgalactosylhydroxylysine glucosidase activity-related genes often need to determine whether a candidate gene is causally involved in collagen processing, extracellular matrix remodeling, or disease pathogenesis. EDITGENE provides a comprehensive suite of CRISPR-based 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 protein-glucosylgalactosylhydroxylysine glucosidase activity research.
Frequently Asked Questions About protein-glucosylgalactosylhydroxylysine glucosidase activity
What is protein-glucosylgalactosylhydroxylysine glucosidase activity?
It is an enzymatic activity (GO:0047402) that removes glucose from a specific disaccharide attached to hydroxylysine residues in collagen and collagen-like proteins.
What reaction does GO:0047402 catalyze?
It catalyzes the hydrolysis of H2O + protein alpha-D-glucosyl-1,2-beta-D-galactosyl-L-hydroxylysine to protein beta-D-galactosyl-L-hydroxylysine and beta-D-glucose.
What genes are involved in protein-glucosylgalactosylhydroxylysine glucosidase activity?
The enzyme itself is encoded by a specific gene, and upstream enzymes like GLT25D1 and GLT25D2 create its substrate. Collagen genes such as COL1A1 and COL3A1 provide the substrate hydroxylysine residues.
What diseases are associated with defects in this activity?
Connective tissue disorders, fibrosis, and cancer have been linked to altered collagen glycosylation, including the step catalyzed by this enzyme.
How can I study protein-glucosylgalactosylhydroxylysine glucosidase activity?
You can use enzymatic assays, CRISPR knockout models, mass spectrometry, and imaging techniques to study its function and regulation.
What are the catalytic residues of this enzyme?
Three crucial carboxyl residues (aspartate and glutamate) were identified by site-directed mutagenesis.
Is protein-glucosylgalactosylhydroxylysine glucosidase activity conserved across species?
The enzyme is found in humans and other vertebrates, and its catalytic residues are conserved, suggesting an important biological role.
What is the substrate of protein-glucosylgalactosylhydroxylysine glucosidase?
The substrate is protein alpha-D-glucosyl-1,2-beta-D-galactosyl-L-hydroxylysine, a glycosylated form of collagen.
What is the product of the reaction catalyzed by GO:0047402?
The products are protein beta-D-galactosyl-L-hydroxylysine and beta-D-glucose.
How does EDITGENE support research on this activity?
EDITGENE offers CRISPR knockout, point mutation, knock-in, overexpression, library screening, and bioinformatics services to study the enzyme and its pathways.
Conclusion
Protein-glucosylgalactosylhydroxylysine glucosidase activity (GO:0047402) is a critical enzymatic function in collagen glycosylation, influencing extracellular matrix stability and tissue homeostasis. Its catalytic mechanism, involving three essential carboxyl residues, has been elucidated through molecular cloning and mutagenesis. Dysregulation of this activity is implicated in connective tissue disorders, fibrosis, and cancer, making it a compelling target for therapeutic intervention. Advances in CRISPR-based genome editing and screening technologies are poised to accelerate our understanding of this enzyme's physiological roles and its potential as a drug target. EDITGENE provides comprehensive services to support these research efforts, from custom knockout models to high-throughput screening and bioinformatics analysis.
References
- 1. Hamazaki H et al.. 2016. Catalytic site of human protein-glucosylgalactosylhydroxylysine glucosidase: Three crucial carboxyl residues were determined by cloning and site-directed mutagenesis.. Biochem Biophys Res Commun 469(3):357-62 PMID: 26682924
