We have published the structure of cross-β amyloid fibrils formed by TTR in the Proceedings of the National Academy of Sciences ().
The work was led by Dr. Anthony Fitzpatrick and the authors include three generations of my colleagues, directed and mentored by Robert Griffin and Christopher Dobson. The publication has been reviewed in Physics Today (download: Atomic and hierarchical structure of an amyloid fibril | Physics Update – Physics Today). It is a prototypical example of the integration of multiple biophysical techniques to approach mesoscale structure.

Five diverse biophysical techniques were integrated to determine unambiguously the structures of each of the motifs that make up the TTR(105–115) amyloid fibrils. Spanning five orders of magnitude, the overlapping length scales of MAS NMR (0.1–10 Å), X-ray diffraction (3–100 Å), cryo-EM (8–1,000 Å), AFM (30–1,000 Å), and STEM (80–1,000 Å) enabled us to derive self-consistent, high-precision structural restraints on the structure.

Close-up view of the MAS NMR atomic-resolution structure of the triplet fibril fitted into the cryo-EM reconstruction (Center). The background image of the fibril (Left) was taken using TEM. (Scale bar, 50 nm.) The fibril surfaces (Right) are shown at 1.0σ (white) and 2.2σ (yellow) above the mean density, respectively, and the constituent β-sheets are shown in a ribbon representation; oxygen, carbon, and nitrogen atoms are shown in red, gray, and blue, respectively.
Download the PDF:
Atomic structure and hierarchical assembly of a cross-β amyloid fibril
Author AffiliationsEdited by Jonathan S. Weissman, University of California, San Francisco, CA, and approved February 1, 2013 (received for review November 8, 2012)
Abstract
The cross-β amyloid form of peptides and proteins represents an archetypal and widely accessible structure consisting of ordered arrays of β-sheet filaments. These complex aggregates have remarkable chemical and physical properties, and the conversion of normally soluble functional forms of proteins into amyloid structures is linked to many debilitating human diseases, including several common forms of age-related dementia. Despite their importance, however, cross-β amyloid fibrils have proved to be recalcitrant to detailed structural analysis. By combining structural constraints from a series of experimental techniques spanning five orders of magnitude in length scale—including magic angle spinning nuclear magnetic resonance spectroscopy, X-ray fiber diffraction, cryoelectron microscopy, scanning transmission electron microscopy, and atomic force microscopy—we report the atomic-resolution (0.5 Å) structures of three amyloid polymorphs formed by an 11-residue peptide. These structures reveal the details of the packing interactions by which the constituent β-strands are assembled hierarchically into protofilaments, filaments, and mature fibrils.
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