Full-length cellular β-secretase has a trimeric subunit stoichiometry, and its sulfur-rich transmembrane interaction site modulates cytosolic copper compartmentalization
| Autor: | Rikard Blunck, Filip Liebsch, Gerd Multhaup, Silvia Scolari, Tobias Bethge, Hugo McGuire, Derek Bowie, Mark R. P. Aurousseau, Andreas Herrmann |
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| Rok vydání: | 2017 |
| Předmět: |
Models
Molecular 0301 basic medicine Protein Folding Protein Conformation Recombinant Fusion Proteins Protein subunit Green Fluorescent Proteins Biochemistry 03 medical and health sciences Cytosol Bacterial Proteins mental disorders Fluorescence Resonance Energy Transfer Amyloid precursor protein Aspartic Acid Endopeptidases Humans Point Mutation Protein Interaction Domains and Motifs Cysteine Molecular Biology chemistry.chemical_classification Alanine biology Biological Transport Cell Biology Compartmentalization (fire protection) Subcellular localization Transmembrane protein 3. Good health Amino acid Luminescent Proteins HEK293 Cells 030104 developmental biology Amino Acid Substitution Microscopy Fluorescence chemistry Mutagenesis Site-Directed biology.protein Biophysics RNA Interference Amyloid Precursor Protein Secretases Protein Multimerization Copper Intracellular |
| Zdroj: | Journal of Biological Chemistry. 292:13258-13270 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m117.779165 |
| Popis: | The β-secretase (BACE1) initiates processing of the amyloid precursor protein (APP) into Aβ peptides, which have been implicated as central players in the pathology of Alzheimer disease. BACE1 has been described as a copper-binding protein and its oligomeric state as being monomeric, dimeric, and/or multimeric, but the native cellular stoichiometry has remained elusive. Here, by using single-molecule fluorescence and in vitro cross-linking experiments with photo-activatable unnatural amino acids, we show that full-length BACE1, independently of its subcellular localization, exists as trimers in human cells. We found that trimerization requires the BACE1 transmembrane sequences (TMSs) and cytoplasmic domains, with residues Ala463 and Cys466 buried within the trimer interface of the sulfur-rich core of the TMSs. Our 3D model predicts that the sulfur-rich core of the trimeric BACE1 TMS is accessible to metal ions, but copper ions did not trigger trimerization. The results of functional assays of endogenous BACE1 suggest that it has a role in intracellular copper compartmentalization by transferring cytosolic copper to intracellular compartments, while leaving the overall cellular copper concentration unaltered. Adding to existing physiological models, our results provide novel insight into the atypical interactions between copper and BACE1 and into its non-enzymatic activities. In conclusion, therapeutic Alzheimer disease prevention strategies aimed at decreasing BACE1 protein levels should be regarded with caution, because adverse effects in copper homeostasis may occur. |
| Databáze: | OpenAIRE |
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