title: Toxic fibrillar oligomers of amyloid-β have cross-β structure.
abstract: Although amyloid fibers are found in neurodegenerative diseases, evidence points to soluble oligomers of amyloid-forming proteins as the cytotoxic species. Here, we establish that our preparation of toxic amyloid-β(1-42) (Abeta42) fibrillar oligomers (TABFOs) shares with mature amyloid fibrils the cross-β structure, in which adjacent β-sheets adhere by interpenetration of protein side chains. We study the structure and properties of TABFOs by powder X-ray diffraction, EM, circular dichroism, FTIR spectroscopy, chromatography, conformational antibodies, and celluar toxicity. In TABFOs, Abeta42 molecules stack into short protofilaments consisting of pairs of helical β-sheets that wrap around each other to form a superhelix. Wrapping results in a hole along the superhelix axis, providing insight into how Abeta may form pathogenic amyloid pores. Our model is consistent with numerous properties of Abeta42 fibrillar oligomers, including heterogenous size, ability to seed new populations of fibrillar oligomers, and fiber-like morphology.
authors.affiliation: Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, CA 90095, USA.
authors.forename: James C
authors.initials: JC
authors.lastname: Stroud
authors.forename: Cong
authors.initials: C
authors.lastname: Liu
authors.forename: Poh K
authors.initials: PK
authors.lastname: Teng
authors.forename: David
authors.initials: D
authors.lastname: Eisenberg
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000633:toxicity; D002942:Circular Dichroism; D008854:Microscopy, Electron; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry* / Q000633:toxicity; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)