Cross interactions of Aβ peptides implicated in Alzheimer’s disease shape amyloid oligomer structures and aggregation

ABSTRACT: A defining hallmark of Alzheimer's disease (AD) is the synaptic aggregation of the amyloid beta (Aβ) peptide. In vivo, Aβ production results in a diverse mixture of variants, of which Aβ40, Aβ42, and Aβ43 are profusely present in the AD brain, and their relative abundance is recognised to play a role in disease onset and progression. Nonetheless, the occurrence of Aβ40, Aβ42, and Aβ43 hetero-oligomerisation and the subsequent effects on Aβ aggregation remain elusive and were investigated here. Using thioflavin-T (ThT) monitored aggregation assays and native mass spectrometry coupled to ion mobility analysis (IM-MS), we first show that all Aβ peptides are aggregation-competent and self-assemble into homo-oligomers with distinct conformational populations, which are more pronounced between Aβ40 than the longer variants. ThT assays were then conducted on binary mixtures of Aβ variants, revealing that Aβ42 and Aβ43 aggregate independently from Aβ40, but significantly speed-up Aβ40 fibrillation. Aβ42 and Aβ43 were observed to aggregate concurrently and mutually accelerate fibril formation, which likely involves hetero-oligomerisation. Accordingly, native MS analysis revealed pairwise oligomerisation between all variants, with the formation of heterodimers and heterotrimers. Interestingly, IM-MS indicates that hetero-oligomers containing longer Aβ variants are enriched in conformers with lower collision-cross sections when compared to their homo-oligomer counterparts. This suggests that Aβ42 and Aβ43 are capable of remodelling oligomer structure towards a higher compaction level. Altogether, our findings provide a mechanistic description for the hetero-oligomerisation of Aβ variants implicated in AD, contributing to rationalising their in vivo proteotoxic interplay.

INSTRUMENT(S): Synapt MS

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Tanja Habeck  

LAB HEAD: Frederik Lermyte

PROVIDER: PXD057653 | Pride | 2025-01-31

REPOSITORIES: pride