Fig. 3.

Distinct zipper interfaces between protofilament kernels in the two aSyn polymorphs. a, b Residue interactions of two asymmetric units in two opposing protofilaments elucidate packing between and within these two protofilaments in the rod (a) and twister (b) polymorphs (viewed down fibril axis). Residues are colored by hydrophobicity (yellow: hydrophobic; green: polar; red: negative charge; blue: positive charge). c, d An overlay of protofilaments of the rod (blue) and twister (red) polymorphs reveals a conserved kernel of a bent β-arch. e Diffraction patterns of the full-length aSyn fibrils agree with those of NACore and preNAC peptide fibrils. f, g The two protofilaments in the rod (f) and twister (g) polymorphs contact by different residues (space-filled) and have distinct fibril core of tightly packed steric zippers of preNAC (blue) and NACore (red), as previously observed in those peptide fibril structures. PD familial mutation residues are labeled with underlines. The cryo-EM density maps are shown as gray mesh surfaces. Intra-protofilament hydrogen bonds are shown in black dashed lines, and inter-protofilament hydrogen bonds are in magenta