Stabilization of neurotoxic Alzheimer amyloid-beta oligomers by protein engineering

作者：Sandberg Anders; Luheshi Leila M; Sollvander Sofia; de Barros Teresa Pereira; Macao Bertil; Knowles Tuomas P J; Biverstal Henrik; Lendel Christofer; Ekholm Petterson Frida; Dubnovitsky Anatoly; Lannfelt Lars; Dobson Christopher M; Hard Torleif^*

来源：Proceedings of the National Academy of Sciences, 2010, 107(35): 15595-15600.

DOI：10.1073/pnas.1001740107

• amyloid-beta peptide
• protein aggregation
• protein structure
• protofibril
• beta-hairpin conformation

Soluble oligomeric aggregates of the amyloid-beta peptide (A beta) have been implicated in the pathogenesis of Alzheimer's disease (AD). Although the conformation adopted by A beta within these aggregates is not known, a beta-hairpin conformation is known to be accessible to monomeric A beta. Here we show that this beta-hairpin is a building block of toxic A beta oligomers by engineering a double-cysteine mutant (called A beta CC) in which the beta-hairpin is stabilized by an intramolecular disulfide bond. A beta(40)CC and A beta(42)CC 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 A beta aggregates in vivo indicate that the wild-type oligomer structure is preserved and stabilized in A beta CC oligomers. Stable oligomers are expected to become highly toxic and, accordingly, we find that beta-sheet-containing A beta(42)CC 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 A beta(42), in which toxic aggregates are only transiently formed. The possibility of obtaining completely stable and physiologically relevant neurotoxic A beta 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 A beta(42) is more toxic than the shorter A beta(40), and why certain inherited mutations are linked to protofibril formation and early-onset AD.

• 出版日期2010-8-31