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Genetic evidence for transmembrane acetylation by lysosomes
Science (New York, N.Y.)
|September 5, 1986
Summary
Sanfilippo disease type C is linked to a deficient lysosomal enzyme. Patient cells show varying abilities in catalyzing enzyme acetylation and acetyl-CoA/CoA exchange, impacting disease mechanisms.
Area of Science:
- Biochemistry
- Genetics
- Lysosomal Storage Diseases
Background:
- Sanfilippo disease type C results from a deficiency in Acetyl-CoA:alpha-glucosaminide N-acetyltransferase, a key lysosomal enzyme.
- This enzyme facilitates the transfer of acetyl groups from acetyl-coenzyme A (acetyl-CoA) to heparan sulfate within lysosomes.
- The enzyme's function is crucial for cellular waste degradation, and its deficiency leads to the accumulation of glycosaminoglycans.
Purpose of the Study:
- To investigate the specific enzymatic defects in patient-derived cell lines with Sanfilippo disease type C.
- To elucidate the functional consequences of enzyme deficiency on the two proposed half-reactions of Acetyl-CoA:alpha-glucosaminide N-acetyltransferase.
- To identify potential genotype-phenotype correlations based on the residual enzymatic activity in different cell lines.
Main Methods:
- Enzyme kinetics assays were used to measure the activity of Acetyl-CoA:alpha-glucosaminide N-acetyltransferase in patient-derived cell lines.
- The study assessed the enzyme's ability to catalyze both the acetylation of the lysosomal membrane and acetyl-CoA/CoA exchange.
- Cell lines from multiple Sanfilippo type C patient families were analyzed.
Main Results:
- Five of the six analyzed cell lines (from three families) retained the ability to catalyze lysosomal membrane acetylation and acetyl-CoA/CoA exchange.
- One cell line, however, was completely devoid of this specific enzymatic activity.
- These findings suggest heterogeneity in the functional defects among Sanfilippo disease type C patient cells.
Conclusions:
- The study reveals distinct functional deficits in the Acetyl-CoA:alpha-glucosaminide N-acetyltransferase enzyme in different Sanfilippo disease type C cell lines.
- The observed variability in half-reaction catalysis provides insights into the molecular basis of the disease.
- Further research is warranted to understand the implications of these functional differences for disease progression and potential therapeutic strategies.