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Prodomain processing of Asp1 (BACE2) is autocatalytic
I Hussain1, G Christie, K Schneider
1Neurology Centre of Excellence for Drug Discovery, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, United Kingdom.
The Journal of Biological Chemistry
|April 24, 2001
Summary
The study shows that Asp1 (BACE2), an enzyme involved in amyloid precursor protein processing, activates itself through autocatalytic prodomain removal. This self-activation occurs within the cell and is crucial for its function in Alzheimer's disease research.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- Amyloid peptide generation via beta- and gamma-secretase cleavage of amyloid precursor protein is key to Alzheimer's disease.
- Beta-secretase (Asp2/BACE) and its homolog Asp1 (BACE2/DRAP) are implicated in this process.
- Aspartic proteinases typically require prodomain removal for activation.
Purpose of the Study:
- To investigate the activation mechanism of Asp1 (BACE2).
- To determine the site and nature of prodomain processing for Asp1.
- To explore the cellular location and potential for trans-activation of Asp1.
Main Methods:
- Autocatalytic cleavage assays using fusion proteins and synthetic peptides.
- Site-directed mutagenesis of catalytic residues (D110N) and substrate residues.
- Expression of wild-type and mutant Asp1 in COS-7 cells to assess processing and localization.
Main Results:
- Prodomain processing of Asp1 occurs autocatalytically between Leu(62) and Ala(63).
- Mutation of the catalytic aspartic acid residue (D110N) abolished cleavage.
- Mature Asp1 is found on the cell surface, and processing occurs intramolecularly in the ER/early Golgi.
- No other proteinase in COS-7 cells could activate the D110N mutant, indicating Asp1's self-activation.
Conclusions:
- Asp1 (BACE2) undergoes autocatalytic activation via prodomain removal.
- This intramolecular processing occurs within the endoplasmic reticulum/early Golgi.
- Asp1 activation is independent of other cellular proteinases in the studied system.
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