title: Inhibitors of amyloid toxicity based on beta-sheet packing of Abeta40 and Abeta42.
abstract: Amyloid fibrils associated with Alzheimer's disease and a wide range of other neurodegenerative diseases have a cross beta-sheet structure, where main chain hydrogen bonding occurs between beta-strands in the direction of the fibril axis. The surface of the beta-sheet has pronounced ridges and grooves when the individual beta-strands have a parallel orientation and the amino acids are in-register with one another. Here we show that in Abeta amyloid fibrils, Met35 packs against Gly33 in the C-terminus of Abeta40 and against Gly37 in the C-terminus of Abeta42. These packing interactions suggest that the protofilament subunits are displaced relative to one another in the Abeta40 and Abeta42 fibril structures. We take advantage of this corrugated structure to design a new class of inhibitors that prevent fibril formation by placing alternating glycine and aromatic residues on one face of a beta-strand. We show that peptide inhibitors based on a GxFxGxF framework disrupt sheet-to-sheet packing and inhibit the formation of mature Abeta fibrils as assayed by thioflavin T fluorescence, electron microscopy, and solid-state NMR spectroscopy. The alternating large and small amino acids in the GxFxGxF sequence are complementary to the corresponding amino acids in the IxGxMxG motif found in the C-terminal sequence of Abeta40 and Abeta42. Importantly, the designed peptide inhibitors significantly reduce the toxicity induced by Abeta42 on cultured rat cortical neurons.
authors.affiliation: Department of Biochemistry and Cell Biology, Center for Structural Biology, Stony Brook University, Stony Brook, New York 11794-5215, USA.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sato
authors.forename: Pascal
authors.initials: P
authors.lastname: Kienlen-Campard
authors.forename: Mahiuddin
authors.initials: M
authors.lastname: Ahmed
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Huilin
authors.initials: H
authors.lastname: Li
authors.forename: James I
authors.initials: JI
authors.lastname: Elliott
authors.forename: Saburo
authors.initials: S
authors.lastname: Aimoto
authors.forename: Stefan N
authors.initials: SN
authors.lastname: Constantinescu
authors.forename: Jean-Noel
authors.initials: JN
authors.lastname: Octave
authors.forename: Steven O
authors.initials: SO
authors.lastname: Smith
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000187:drug effects / Q000648:ultrastructure; D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D000818:Animals; D052160:Benzothiazoles; D005456:Fluorescent Dyes; D005998:Glycine / Q000737:chemistry; D006801:Humans; D008715:Methionine / Q000737:chemistry; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects; D019906:Nuclear Magnetic Resonance, Biomolecular; D009842:Oligopeptides / Q000494:pharmacology*; D010446:Peptide Fragments / Q000737:chemistry* / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D051381:Rats; D013050:Spectrometry, Fluorescence; D013844:Thiazoles
chemical_list: D000682:Amyloid; D016229:Amyloid beta-Peptides; D052160:Benzothiazoles; D005456:Fluorescent Dyes; D009842:Oligopeptides; D010446:Peptide Fragments; D013844:Thiazoles; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); C009462:thioflavin T; D008715:Methionine; D005998:Glycine