Distinguishing the cross‐β spine arrangements in amyloid fibrils using FRET analysis

Abstract

The recently published microcrystal structures of amyloid fibrils from small peptides greatly enhanced our understanding of the atomic‐level structure of the amyloid fibril. However, only a few amyloid fibrils can form microcrystals. The dansyl‐tryptophan fluorescence resonance energy transfer (FRET) pair was shown to be able to detect the inter‐peptide arrangement of the Transthyretin (105–115) amyloid fibril. In this study, we combined the known microcrystal structures with the corresponding FRET efficiencies to build a model for amyloid fibril structure classification. We found that fibrils with an antiparallel structural arrangement gave the largest FRET signal, those with a parallel arrangement gave the lowest FRET signal, and those with a mixed arrangement gave a moderate FRET signal. This confirms that the amyloid fibril structure patterns can be classified based on the FRET efficiency.