Resonance assignments of an α-synuclein fibril prepared in Tris buffer at moderate ionic strength.

Fibrils of the protein α-synuclein (α-syn) are implicated in the pathogenesis of Parkinson's disease and related neurodegenerative disorders. We have reported a high-resolution structure (PDB 2N0A) of an α-syn fibril form prepared by in vitro incubation of monomeric protein in 50 mM sodium phosphate buffer pH 7.4 with 0.1 mM EDTA and 0.01% sodium azide. In parallel with this structure determination, ongoing studies of small molecule ligands binding to α-syn fibrils, prepared in 2-amino-2-(hydroxymethyl)-1,3-propanediol (Tris) buffer, have been in progress, and it is therefore of interest to determine the structural similarity of these forms. Here we report the 13C and 15N resonance assignments for α-syn fibrils prepared with Tris-HCl buffer (pH 7.7 at 37 °C) and 100 mM NaCl. These fibrillization conditions yield a form with fibril core chemical shifts highly similar to those we reported (BMRB 16939) in the course of determining the high-resolution 2N0A structure, with the exception of some small perturbations from T44 to V55, including two sets of peaks observed for residues T44-V48. Additional differences occur in the patterns of observed residues in the primarily unstructured N-terminus. These results demonstrate a common fold of the fibril core for α-syn fibrils prepared in phosphate or Tris-HCl buffer at moderate ionic strength.