Molecular conformation and dynamics of the Y145Stop variant of human prion protein in amyloid fibrils.
A C-terminally truncated Y145Stop variant of the human prion protein (huPrP23-144) is associated with a hereditary amyloid disease known as PrP cerebral amyloid angiopathy. Previous studies have shown that recombinant huPrP23-144 can be efficiently converted in vitro to the fibrillar amyloid state, and that residues 138 and 139 play a critical role in the amyloidogenic properties of this protein. Here, we have used magic-angle spinning solid-state NMR spectroscopy to provide high-resolution insight into the protein backbone conformation and dynamics in fibrils formed by (13)C,(15)N-labeled huPrP23-144. Surprisingly, we find that signals from approximately 100 residues (i.e., approximately 80% of the sequence) are not detected above approximately -20 degrees C in conventional solid-state NMR spectra. Sequential resonance assignments revealed that signals, which are observed, arise exclusively from residues in the region 112-141. These resonances are remarkably narrow, exhibiting average (13)C and (15)N linewidths of approximately 0.6 and 1 ppm, respectively. Altogether, the present findings indicate the existence of a compact, highly ordered core of huPrP23-144 amyloid encompassing residues 112-141. Analysis of (13)C secondary chemical shifts identified likely beta-strand segments within this core region, including beta-strand 130-139 containing critical residues 138 and 139. In contrast to this relatively rigid, beta-sheet-rich amyloid core, the remaining residues in huPrP23-144 amyloid fibrils under physiologically relevant conditions are largely unordered, displaying significant conformational dynamics.
Helmus
Jonathan J
JJ
Department of Chemistry, Ohio State University, Columbus, OH 43210, USA.
Surewicz
Krystyna
K
Nadaud
Philippe S
PS
Surewicz
Witold K
WK
Jaroniec
Christopher P
CP
D000682:Amyloid / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D008968:Molecular Conformation; D050505:Mutant Proteins / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011328:Prions / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013696:Temperature
D000682:Amyloid; D050505:Mutant Proteins; D011328:Prions