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

doi:10.1073/pnas.0608447104

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

Departments of *Physiology and Biophysics and
^†Chemistry, Case Western Reserve University, Cleveland, OH 44106

Edited by Arthur Horwich, Yale University School of Medicine, New Haven, CT, and approved December 4, 2006 (received for review September 25, 2006)

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 β-sheet core of PrP amyloid to the C-terminal region (staring at residue ≈169) that in the native structure of PrP monomer corresponds to α-helix 2, a major part of α-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 β-structure. These data provide long-sought experimentally derived constraints for high-resolution structural models of PrP amyloid fibrils.

Footnotes

^‡To whom correspondence should be addressed at:
Department of Physiology and Biophysics, Case Western Reserve University, 2109 Adelbert Road, Cleveland, OH 44106.
E-mail: witold.surewicz{at}case.edu
Author contributions: X.L., P.L.W., and W.K.S. designed research; X.L. performed research; X.L., P.L.W., and W.K.S. analyzed data; and W.K.S. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS direct submission.
Abbreviations:

TSE,

transmissible spongiform encephalopathy;

PrP,

prion protein;

huPrP90–231,

recombinant human PrP fragment 90–231;

HXMS,

H/D exchange combined with MS;

PK,

proteinase K.