title: Identification of physiological and toxic conformations in Abeta42 aggregates.
abstract: Aggregation of the 42-residue amyloid beta-protein (Abeta42) plays a crucial role in the pathogenesis of Alzheimer's disease (AD). Despite numerous structural studies on Abeta aggregates, the relationship between tertiary structure and toxicity remains unclear. Our proline scanning and solid-state NMR studies suggested that aggregates both of wild-type Abeta42 and of E22K-Abeta42 (one of the mutants related to cerebral amyloid angiopathy) contain two conformers: a major one with a turn at positions 25 and 26, and a minor one with a turn at positions 22 and 23. To identify the toxic conformer, the derivative Abeta42-lactam(22K-23E), in which the side chains at positions 22 and 23 were covalently linked, was synthesized as a minor conformer surrogate, along with Abeta42-lactam(25K-26E) as a major conformer surrogate. The Abeta42-lactam(22K-23E) showed stronger aggregation, neurotoxicity, radical generation, and oligomerization than wild-type Abeta42, whereas in Abeta42-lactam(25K-26E) were weak. The transition from the physiological conformation with a turn at positions 25 and 26 to the toxic conformation with a turn at positions 22 and 23 might be a key event in the pathogenesis of AD.
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Masuda
authors.forename: Satoko
authors.initials: S
authors.lastname: Uemura
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Ohashi
authors.forename: Azusa
authors.initials: A
authors.lastname: Nakanishi
authors.forename: K
authors.initials: K
authors.lastname: Takegoshi
authors.forename: Takahiko
authors.initials: T
authors.lastname: Shimizu
authors.forename: Takuji
authors.initials: T
authors.lastname: Shirasawa
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Irie
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D009154:Mutation; D016716:PC12 Cells; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D051381:Rats; D015203:Reproducibility of Results
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); D011392:Proline