Fig. 3. Hsp104:casein extended-state conformation advances substrate contacts.
(A) Cryo-EM reconstruction of Hsp104:casein identifying substrate (yellow) and an extended conformation of protomers P1 and P6. (B) Filtered map of P1 (red), and P6 (magenta) overlaid with the corresponding closed-state protomers (grey) following alignment to P4 in the hexamer. NBD conformational changes (arrows) resulting in extended-state interactions (black circles) with substrate (yellow) and the P2-NBD2 (orange) are shown. (C) Model and map of the P6 NBD1 and NBD2 pore loops showing change in the pore loop position (arrow) compared to the closed state (grey) for NBD1 and substrate contact by Y257 and Y662 (green). (D) Model and map of the NBD1 and NBD2 P1–P6 spiral of pore loop-substrate interactions.