Arylsulfatase B Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
| Arylsulfatase B (ARSB) |
|---|
| Protein Name | Arylsulfatase B |
| Gene | ARSB |
| UniProt ID | P15884 |
| PDB IDs | 1FSH, 2GUJ, 3BBO |
| Molecular Weight | 55.8 kDa (precursor), 42 kDa (mature) |
| Subcellular Localization | Lysosome |
| Protein Family | Sulfatase family |
Arylsulfatase B (ARSB) is a lysosomal hydrolase enzyme that catalyzes the removal of sulfate groups from glycosaminoglycans (GAGs), specifically dermatan sulfate and chondroitin sulfate. This enzyme is essential for the normal degradation and recycling of these complex carbohydrates within lysosomes.
¶ Domain Architecture
- Signal Peptide: 21 amino acids for ER targeting
- Propeptide: 24 amino acids removed during processing
- Sulfatase Domain: ~400 amino acids containing the catalytic site
- Formylglycine Cofactor: Unusual post-translational modification essential for catalytic activity
- The enzyme adopts a sulfatase fold characteristic of all sulfatases
- Active site contains a conserved cysteine/formylglycine
- Two N-glycosylation sites for proper folding and stability
- Dimeric in the active form
- Formylglycine (FGly) Modification: Catalytic residue generated from a cysteine at position 51
- N-linked Glycosylation: Multiple sites for carbohydrate attachment
- Phosphorylation: Some regulatory phosphorylation sites identified
- Catalyzes hydrolysis of sulfate ester bonds at the non-reducing end of GAGs
- Specifically targets 4-sulfate groups on dermatan sulfate and chondroitin sulfate
- Optimal activity at acidic pH (5.0-5.5) consistent with lysosomal environment
- Requires metal ions (Ca²⁺) for structural stability
- Final step in lysosomal degradation of dermatan sulfate
- Completes the breakdown cascade initiated by other sulfatases
- Prevents accumulation of partially degraded GAGs
- Maintains lysosomal function and cellular homeostasis
- Prevents accumulation of toxic GAG fragments
- Essential for normal proteoglycan turnover
Also known as Maroteaux-Lamy syndrome, MPS VI is caused by deficiency of Arylsulfatase B activity.
Pathogenesis:
- Accumulation of dermatan sulfate in lysosomes
- Progressive storage of GAGs in multiple tissues
- Systemic clinical manifestations
Disease Progression:
- Severe cases: rapid progression with early death
- Attenuated cases: slower progression, longer survival
- Neurological involvement varies by case
- Galsulfase (Naglazyme®): FDA-approved recombinant human ARSB
- Weekly intravenous infusions
- Improves endurance and functional abilities
- Does not cross the blood-brain barrier
- AAV-mediated gene delivery in development
- Potential for CNS-directed therapy
- Challenges with blood-brain barrier penetration
- Small molecules reducing GAG synthesis
- Being explored for MPS VI treatment
- Bond CS, et al. (1997). "Structure of arylsulfatase B." Nat Struct Biol. PMID:9278053
- Roberts SH, et al. (2006). "Crystal structure of human arylsulfatase B." J Mol Biol. PMID:16403646
- Harmatz P, et al. (2018). "Enzyme replacement therapy for mucopolysaccharidosis VI: 10-year outcomes." Mol Genet Metab. PMID:29428225
The study of Arylsulfatase B Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.