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Solid-State NMR Study of Amyloid Nanocrystals and Fibrils Formed by the Peptide GNNQQNY from Yeast Prion Protein Sup35p
journal contribution
posted on 2007-04-25, 00:00 authored by Patrick C. A. van der Wel, Józef R. Lewandowski, Robert G. GriffinSup35p is a prion protein found in yeast that contains a prion-forming domain characterized by
a repetitive sequence rich in Gln, Asn, Tyr, and Gly amino acid residues. The peptide GNNQQNY7-13 is
one of the shortest segments of this domain found to form amyloid fibrils, in a fashion similar to the protein
itself. Upon dissolution in water, GNNQQNY displays a concentration-dependent polymorphism, forming
monoclinic and orthorhombic crystals at low concentrations and amyloid fibrils at higher concentrations.
We prepared nanocrystals of both space groups as well as fibril samples that reproducibly contain three
(coexisting) structural forms and examined the specimens with magic angle spinning (MAS) solid-state
nuclear magnetic resonance. 13C and 15N MAS spectra of both nanocrystals and fibrils reveal narrow
resonances indicative of a high level of microscopic sample homogeneity that permitted resonance
assignments of all five species. We observed variations in chemical shift among the three dominant forms
of the fibrils which were indicated by the presence of three distinct, self-consistent sets of correlated NMR
signals. Similarly, the monoclinic and orthorhombic crystals exhibit chemical shifts that differ from one another
and from the fibrils. Collectively, the chemical shift data suggest that the peptide assumes five conformations
in the crystals and fibrils that differ from one another in subtle but distinct ways. This includes variations in
the mobility of the aromatic Tyr ring. The data also suggest that various structures assumed by the peptide
may be correlated to the “steric zipper” observed in the monoclinic crystals.
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chemical shiftpeptideform amyloid fibrils13 CPeptide GNNQQNYAmyloid Nanocrystalschemical shift dataamyloid fibrilssample homogeneityacid residuesresonance assignmentsYeast Prion Protein Sup 35pSupNMR signals15 N MAS spectraspace groupsfibril samplesTyr ringcrystals exhibit chemical shiftsGNNQQNY displaysmagic angleprion protein
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