Fig. 4: Structural comparison of hClpXPIA and hClpXP reveals major conformational changes.
From: Cryo-EM structures of human ClpXP reveal mechanisms of assembly and proteolytic activation
a atomic model of hClpXPIA and hClpXPX-linked docked into low-resolution cryo-EM maps of hClpXP initial assembly and uncrosslinked hClpXP complex, respectively. b The LGF loop from hClpX chain E in the intermediate state is situated in the hydrophobic pocket formed between hClpP subunits I and J, while the loop shifts to the neighboring pocket formed between subunits I and H in the hClpXP complex. c The ATPase and protease rings rotate approximately 10 degrees relative to one another during the transition from the initial assembly state to the fully assembled complex. d The ATPase ring of the hClpXPIA state adopts a wider, more open conformation that does not contain substrate, compared to the substrate-bound hClpX. Further, the staircase organization of the ATPase domains is not as prominent in hClpXPIA, with substrate binding inducing chains F and A move slightly upward, and chains D and E to move slightly downward to form the canonical substrate-bound staircase.
