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

Fibrils of the protein alpha-synuclein (alpha-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 alpha-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 alpha-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 C-13 and N-15 resonance assignments for alpha-syn fibrils prepared with Tris-HCl buffer (pH 7.7 at 37 A degrees 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 alpha-syn fibrils prepared in phosphate or Tris-HCl buffer at moderate ionic strength.