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P4‐316: Stabilization of neurotoxic Alzheimer amyloid‐beta oligomers by protein engineering
Author(s) -
Dubnovitsky Anatoly,
Sandberg Anders,
Luheshi Leila,
Söllvander Sofia,
Barros Teresa Pereira,
Macao Bertil,
Knowles Tuomas,
Biverstål Henrik,
Lendel Christofer,
EkholmPetterson Frida,
Lannfelt Lars,
Dobson Christopher,
Härd Torleif
Publication year - 2011
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2011.09.061
Subject(s) - oligomer , chemistry , fibril , amyloid (mycology) , peptide , biophysics , cysteine , in vitro , in vivo , amyloid beta , protein aggregation , monomer , biochemistry , biology , enzyme , inorganic chemistry , organic chemistry , polymer , microbiology and biotechnology
Soluble oligomeric aggregates of the amyloid-β peptide (Aβ) have been implicated in the pathogenesis of Alzheimer’s disease (AD). Although the conformation adopted by Aβ within these aggregates is not known, a β-hairpin conformation is known to be accessible to monomeric Aβ. Here we show that this β-hairpin is a building block of toxic Aβ oligomers by engineering a doublecysteine mutant (called AβCC) in which the β-hairpin is stabilized by an intramolecular disulfide bond. Aβ40CC and Aβ42CC both spontaneously form stable oligomeric species with distinct molecular weights and secondary-structure content, but both are unable to convert into amyloid fibrils. Biochemical and biophysical experiments and assays with conformation-specific antibodies used to detect Aβ aggregates in vivo indicate that the wild-type oligomer structure is preserved and stabilized in AβCC oligomers. Stable oligomers are expected to become highly toxic and, accordingly, we find that β-sheet-containing Aβ42CC oligomers or protofibrillar species formed by these oligomers are 50 times more potent inducers of neuronal apoptosis than amyloid fibrils or samples of monomeric wild-type Aβ42, in which toxic aggregates are only transiently formed. The possibility of obtaining completely stable and physiologically relevant neurotoxic Aβ oligomer preparations will facilitate studies of their structure and role in the pathogenesis of AD. For example, here we show how kinetic partitioning into different aggregation pathways can explain why Aβ42 is more toxic than the shorter Aβ40, and why certain inherited mutations are linked to protofibril formation and early-onset AD.