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Abstract
The still elusive structural difference of non-infectious and infectious amyloid of the mammalian prion protein (PrP) is a major pending milestone in understanding protein-mediated infectivity in neurodegenerative diseases. Preparations of PrP-amyloid proven to be infectious have never been investigated with a high-resolution technique. All available models to date have been based on low-resolution data. Here, we establish protocols for the preparation of infectious samples of full-length recombinant (rec) PrP-amyloid in NMR-sufficient amounts by spontaneous fibrillation and seeded fibril growth from brain extract. We link biological and structural data of infectious recPrP-amyloid, derived from bioassays, atomic force microscopy, and solid-state NMR spectroscopy. Our data indicate a semi-mobile N‑terminus, some residues with secondary chemical shifts typical of α‑helical secondary structure in the middle part between ∼115 to ∼155, and a distinct β‑sheet core C‑terminal of residue ∼155. These findings are not in agreement with all current models for PrP-amyloid. We also provide evidence that samples seeded from brain extract may not differ in the overall arrangement of secondary structure elements, but rather in the flexibility of protein segments outside the β-core region. Taken together, our protocols provide an essential basis for the high-resolution characterization of non-infectious and infectious PrP-amyloid in the near future.
Disclosure of Potential Conflicts of Interest
No potential conflicts of interest were disclosed.
Acknowledgments
We thank Bernd Esters for recPrP(25‑233) expression and the precision engineering workshop of Waldemar Seidel for MAS-rotor inserts. We are deeply indebted to Detlev Riesner, Filipp Oesterhelt, Eva Birkmann, and Christian Dumpitak for fruitful discussions.
Supplemental Material
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