[NMR paper] Higher Order Amyloid Fibril Structure by MAS NMR and DNP Spectroscopy.

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Higher Order Amyloid Fibril Structure by MAS NMR and DNP Spectroscopy.

Related Articles Higher Order Amyloid Fibril Structure by MAS NMR and DNP Spectroscopy.

J Am Chem Soc. 2013 Dec 4;

Authors: Debelouchina GT, Bayro MJ, Fitzpatrick AW, Ladizhansky V, Colvin MT, Caporini MA, Jaroniec CP, Bajaj VS, Rosay MM, Macphee CE, Vendruscolo M, Maas WE, Dobson CM, Griffin RG

Abstract
Protein magic angle spinning (MAS) NMR spectroscopy has generated structural models of several amyloid fibril systems, thus providing valuable information regarding the forces and interactions that afford the extraordinary stability of amyloid. Despite these advances, however, obtaining atomic resolution structural information constraining the higher levels of structural organization within the fibrils remains a significant challenge. Here, we detail MAS NMR experiments and sample labeling schemes designed specifically to probe higher order amyloid structure and we have applied them to the fibrils formed by an eleven-residue segment of the amyloidogenic protein transthyretin (TTR(105-115)). These experiments have allowed us to unambiguously define not only the ?-strand arrangement of the peptide into ?-sheets and the ?-sheet interface within each protofilament, but also to identify the nature of the protofilament-to-protofilament contacts that lead to the formation of the complete fibril. Our efforts have resulted in 111 quantitative distance and torsion angle restraints (10 per residue). The experiments benefited extensively from the use of dynamic nuclear polarization (DNP), which in some cases allowed us to shorten the data acquisition time from days to hours and to significantly improve the signal-to-noise of the spectra. The ?-sheet interface and protofilament interactions identified result in local variations in the structure producing multiple peaks for the N- and C-termini of the peptide and inhomogeneous line-broadening for the buried residues of the peptide.


PMID: 24304221 [PubMed - as supplied by publisher]



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