De novo designed peptide-based amyloid fibrils

AUTOR(ES)
FONTE

National Academy of Sciences

RESUMO

Identification of therapeutic strategies to prevent or cure diseases associated with amyloid fibril deposition in tissue (Alzheimer's disease, spongiform encephalopathies, etc.) requires a rational understanding of the driving forces involved in the formation of these organized assemblies rich in β-sheet structure. To this end, we used a computer-designed algorithm to search for hexapeptide sequences with a high propensity to form homopolymeric β-sheets. Sequences predicted to be highly favorable on this basis were found experimentally to self-associate efficiently into β-sheets, whereas point mutations predicted to be unfavorable for this structure inhibited polymerization. However, the property to form polymeric β-sheets is not a sufficient requirement for fibril formation because, under the conditions used here, preformed β-sheets from these peptides with charged residues form well defined fibrils only if the total net charge of the molecule is ±1. This finding illustrates the delicate balance of interactions involved in the formation of fibrils relative to more disordered aggregates. The present results, in conjunction with x-ray fiber diffraction, electron microscopy, and Fourier transform infrared measurements, have allowed us to propose a detailed structural model of the fibrils.

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