Aβ(39–42) Modulates Aβ Oligomerization but Not Fibril Formation
| Autor: | Huiyuan Li, Gal Bitan, Megan Murray Gessel, Chun Wu, Joan-Emma Shea, Michael T. Bowers |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Amyloid
Spectrometry Mass Electrospray Ionization Molecular Sequence Data Molecular Dynamics Simulation Mass spectrometry PC12 Cells Biochemistry Article Amyloid beta-Protein Precursor chemistry.chemical_compound Molecular dynamics Fibril formation Animals Humans Amino Acid Sequence Benzothiazoles Peptide sequence Amyloid beta-Peptides Protein multimerization Peptide Fragments Rats Thiazoles Crystallography Spectrometry Fluorescence Dodecameric protein Monomer Microscopy Fluorescence chemistry Biophysics Protein Multimerization |
| Zdroj: | Biochemistry. 51:108-117 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi201520b |
| Popis: | Recently, certain C-terminal fragments (CTFs) of Aβ42 have been shown to be effective inhibitors of Aβ42 toxicity. Here, we examine the interactions between the shortest CTF in the original series, Aβ(39-42), and full-length Aβ. Mass spectrometry results indicate that Aβ(39-42) binds directly to Aβ monomers and to the n = 2, 4, and 6 oligomers. The Aβ42:Aβ(39-42) complex is further probed using molecular dynamics simulations. Although the CTF was expected to bind to the hydrophobic C-terminus of Aβ42, the simulations show that Aβ(39-42) binds at several locations on Aβ42, including the C-terminus, other hydrophobic regions, and preferentially in the N-terminus. Ion mobility-mass spectrometry (IM-MS) and electron microscopy experiments indicate that Aβ(39-42) disrupts the early assembly of full-length Aβ. Specifically, the ion-mobility results show that Aβ(39-42) prevents the formation of large decamer/dodecamer Aβ42 species and, moreover, can remove these structures from solution. At the same time, thioflavin T fluorescence and electron microscopy results show that the CTF does not inhibit fibril formation, lending strong support to the hypothesis that oligomers and not amyloid fibrils are the Aβ form responsible for toxicity. The results emphasize the role of small, soluble assemblies in Aβ-induced toxicity and suggest that Aβ(39-42) inhibits Aβ-induced toxicity by a unique mechanism, modulating early assembly into nontoxic hetero-oligomers, without preventing fibril formation. |
| Databáze: | OpenAIRE |
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