β-Sheet core of human prion protein amyloid fibrils as determined by hydrogen/deuterium exchange

Abstract

Propagation of transmissible spongiform encephalopathies is associated with the conversion of normal prion protein, PrP C , into a misfolded, oligomeric form, PrP Sc . Although the high-resolution structure of the PrP C is well characterized, the structural properties of PrP Sc remain elusive. Here we used MS analysis of H/D backbone amide exchange to examine the structure of amyloid fibrils formed by the recombinant human PrP corresponding to residues 90 -231 (PrP90 -231), a misfolded form recently reported to be infectious in transgenic mice overexpressing PrP C . Analysis of H/D exchange data allowed us to map the systematically H-bonded ␤-sheet core of PrP amyloid to the C-terminal region (staring at residue Ϸ169) that in the native structure of PrP monomer corresponds to ␣-helix 2, a major part of ␣-helix 3, and the loop between these two helices. No extensive hydrogen bonding (as indicated by the lack of significant protection of amide hydrogens) was detected in the N-terminal part of PrP90 -231 fibrils, arguing against the involvement of residues within this region in stable ␤-structure. These data provide long-sought experimentally derived constraints for high-resolution structural models of PrP amyloid fibrils.prion diseases ͉ transmissible spongiform encephalopathy ͉ amyloid structure ͉ mass spectrometry

Molecular architecture of human prion protein amyloid: A parallel, in-register β-structure

“…Consistent with the established increase in ␤-structure content upon conversion to amyloid (20,29), the only scenario compatible with the present data is that residues within this "core" region stack as single molecule layers with close proximity of same residues in the adjacent PrP molecules. The location of this tightly packed ␤-sheet region correlates remarkably well with recent H/D exchange studies conducted in our laboratory (19), which mapped an exchangeprotected core to residues Ϸ169-221.…”

“…This critical gap in TSE research largely reflects experimental difficulties in structural studies of large protein aggregates such as amyloid fibrils. Our recent hydrogen/ deuterium (H/D) exchange study has provided an initial lowresolution insight into the location of the ␤-sheet core in the recombinant PrP amyloid (19). However, the molecular architecture of this core region remains unknown.…”

Determination of amyloid core structure using chemical shifts

“…24,25 Instead, a variety of studies have investigated the structure of amyloid fibrils produced in vitro from recombinant PrP. [26][27][28][29][30][31][32][33][34][35] Hereditary prion diseases include C-terminally truncated variants of the PrP, Y145X, Q160X, Y226X, and Q227X. Previously, we showed that the b-sheet content is highly similar in amyloid fibrils of the Y145X and Q160X stop mutants of human PrP.…”

Dynamics of a truncated prion protein, PrP(113–231), from 15N NMR relaxation: Order parameters calculated and slow conformational fluctuations localized to a distinct region

“…[10][11][12] There has been some recent progress in defining the molecular architecture of prion amyloid fibers. 13,14 The mammalian prion proteins have a high homology at the sequence and structural level. All mammalian PrP C studied consist of two structurally distinct domains.…”