Symmetry-free cryo-EM structures of the chaperonin TRiC along its ATPase-driven conformational cycle.

ABSTRACT: The eukaryotic group II chaperonin TRiC/CCT is a 16-subunit complex with eight distinct but similar subunits arranged in two stacked rings. Substrate folding inside the central chamber is triggered by ATP hydrolysis. We present five cryo-EM structures of TRiC in apo and nucleotide-induced states without imposing symmetry during the 3D reconstruction. These structures reveal the intra- and inter-ring subunit interaction pattern changes during the ATPase cycle. In the apo state, the subunit arrangement in each ring is highly asymmetric, whereas all nucleotide-containing states tend to be more symmetrical. We identify and structurally characterize an one-ring closed intermediate induced by ATP hydrolysis wherein the closed TRiC ring exhibits an observable chamber expansion. This likely repres

SUBMITTER: Cong Y 

PROVIDER: S-EPMC3273382 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature