Abstract

This presentation will focus mainly on the structural analysis of amyloid fibrils with cryo microscopy and on the generation and characterisation of a conformation-sensitive antibody domain.

(1) Previously, cryo microscopy yielded for one morphology of an Alzheimer’s Aβ(1-40) amyloid fibril a density map at 26 Å resolution [Sachse et al. J. Mol. Biol. 362, 347f. (2006)]. More recently, we have explored the structural heterogeneity of different Aβ(1-40) amyloid fibrils in more detail and obtained, for one fibril morphology, a structural resolution of less than 10 Å. For this fibril we could determine the packing of the β-sheet structure and its protofilament organisation. The observed structure differs significantly from previous proposals on the protofilament-protofilament interactions of amyloid fibrils in Alzheimer’s disease. By contrast, it is similar to recently described steric zipper structures [Sawaya et al. Nature 447, 453-457 (2007)].

(2) We have generated an antibody domain, termed B10 , that recognizes an amyloid-specific and conformationally defined epitope [Habicht et al. PNAS 104 , 19232–7, (2007)]. This antibody domain was selected by phage-display from a recombinant library of camelid antibody domains. Surface plasmon resonance, immunoblots and immunohistochemistry show that this antibody domain distinguishes Aβ amyloid fibrils from disaggregated Aβ peptide as well as from specific Aβ oligomers. The antibody domain possesses functional activity in preventing the formation of mature amyloid fibrils by stabilizing Aβ protofibrils. These data suggest possible applications of B10 in the detection of amyloid fibrils or in the modulation of their formation.