In this paper, we demonstrate the effects of genetically fusing a demonstrated amyloidogenic sequence (retro-CspA) to a well-known, highly-soluble, globular protein (EGFP, a green fluorescent protein variant). We show that the retro-CspA sequence component of this genetic fusion causes the fusion protein to aggregate and precipitate into amyloid fibers which are thioflavin-binding competent, indicating that the fusion protein aggregates. At the same time, the amyloid fibers obtained contain significant native EGFP which is also fluorescent, indicating that the amyloid fibers contain the EGFP sequence folded into a protein which cannot be held to have been distorted through aggregation because it is still fluorescent. EFGP and GFP fluorescence are both very sensitive to any structural distortion or perturbation. Thus, the work suggests that all chain sections of a protein which is deposited into amyloids are not necessarily stripped of all native structure, and re-structured into intermolecular beta sheets of the cross-beta variety. Rather, amyloids can contain chains in native structure; in this case, retaining sufficient native structure for EGFP to continue to fluoresce from within the amyloid.

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