Fig. 3.
3D arrangement of the ASC-PYD filament. (A and B) Top (A) and side (B) views of the ASC-PYD filament in surface representation. The three helical oligomer strands are colored blue, teal, and dark blue, and individual ASC-PYD subunits have alternating darker and lighter shades. (C) Four ASC-PYD monomers are shown in surface representation as part of the filament using the color code in A and B. Three interaction interfaces I–III are indicated by dashed square rectangles. (D–F) Detailed view of interaction interfaces I–III, respectively. Intermolecular atom-pair contacts observed as ambiguous peaks by solid-state NMR spectroscopy and identified by CANDID are indicated by solid black lines. The residues defining interfaces I, II, and III are labeled and colored orange, yellow, and red, respectively. (G) Chemical-shift differences between solution- and solid-state chemical shifts for the nucleus 15N, 13Cα, and 13Cβ. Chemical-shift variations larger than the mean value are marked with different color codes on the secondary structure elements. Residues that belong to the type I, II, and III interfaces are marked in orange, yellow, and red, respectively. (H) Structural location of the residues with significant chemical-shift differences between the monomeric and filament forms, as identified and using the color code in G. (I) Structural details of interface type I as indicated by the dashed square rectangle in H. Side chains involved in intersubunit salt bridges are shown as stick models and with their sequence labels.