PMID: 30955883

Authors:

Gestaut D, Roh SH, Ma B, Pintilie G, Joachimiak LA, Leitner A, Walzthoeni T, Aebersold R, Chiu W, Frydman J

Title:

The Chaperonin TRiC/CCT Associates with Prefoldin through a Conserved Electrostatic Interface Essential for Cellular Proteostasis.

Journal:

Cell. 2019 Apr 18;177(3):751-765.e15. doi: 10.1016/j.cell.2019.03.012. Epub 2019 , Apr 4.

Abstract:

Maintaining proteostasis in eukaryotic protein folding involves cooperation of distinct chaperone systems. To understand how the essential ring-shaped chaperonin TRiC/CCT cooperates with the chaperone prefoldin/GIMc (PFD), we integrate cryoelectron microscopy (cryo-EM), crosslinking-mass-spectrometry and biochemical and cellular approaches to elucidate the structural and functional interplay between TRiC/CCT and PFD. We find these hetero-oligomeric chaperones associate in a defined architecture, through a conserved interface of electrostatic contacts that serves as a pivot point for a TRiC-PFD conformational cycle. PFD alternates between an open "latched" conformation and a closed "engaged" conformation that aligns the PFD-TRiC substrate binding chambers. PFD can act after TRiC bound its substrates to enhance the rate and yield of the folding reaction, suppressing non-productive reaction cycles. Disrupting the TRiC-PFD interaction in vivo is strongly deleterious, leading to accumulation of amyloid aggregates. The supra-chaperone assembly formed by PFD and TRiC is essential to prevent toxic conformations and ensure effective cellular proteostasis.