Structure of prion protein amyloid fibrils as determined by hydrogen /deuterium exchange

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" Structure of prion protein amyloid fibrils as determined by hydrogen /deuterium exchange "
Xiaojun Lu W. K. Surewicz

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	52484
Doc. No	:	TL22438
Call number	:	‭3300677‬
Main Entry	:	Xiaojun Lu
Title & Author	:	Structure of prion protein amyloid fibrils as determined by hydrogen /deuterium exchange\ Xiaojun Lu
College	:	Case Western Reserve University
Date	:	2008
Degree	:	Ph.D.
student score	:	2008
Page No	:	135
Abstract	:	Propagation of transmissible spongiform encephalopathies is associated with the conversion of normal prion protein, PrPC, into a misfolded, oligomeric form, PrPSc. While the high-resolution structure of PrPC is well characterized, the structural properties of PrPSc remain elusive. Here we used mass spectroscopic analysis of hydrogen/deuterium backbone amide exchange (HXMS) to examine the structure of amyloid fibrils formed by the recombinant human prion protein corresponding to residues 90-231 (PrP90-231), a misfolded form recently reported to be infectious in transgenic mice overexpressing PrPC. Analysis of H/D exchange data allowed us to map the systematically hydrogen-bonded β-sheet core of PrP amyloid to the C-terminal region (starting at residue ∼169) that in the native structure of the 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. HXMS was also employed to examine the structure of amyloid fibrils formed by D178N huPrP90-231, a PrP variant associated with familial prion diseases. We found that the D178N substitution had no significant effect on the location of the amyloid core of huPrP90-231 fibrils. Finally, these studies were extended to amyloid fibrils formed by protein misfolding cyclic amplification (PMCA) procedure, in which the conversion of the recombinant Syrian hamster PrP90-231 is “seeded” by brain-derived PrPSc. We found that the PMCA product contains two (possibly three) populations of PrP molecules. In one of them, the amyloid core is extended N-terminally up to residue ∼145. Even in this case, however, this systematically hydrogen-bonded core region is shorter as compared to the “core” as defined by resistance to proteinase K digestion, suggesting that protection against proteinase K digestion does not necessarily reflect the presence of cross-β-structure.
Subject	:	Pure sciences; Amyloid fibrils; Hydrogen/deuterium exchange; Prion proteins; Analytical chemistry; Chemistry; 0486:Analytical chemistry; 0494:Chemistry
Added Entry	:	W. K. Surewicz
Added Entry	:	Case Western Reserve University