Cell
Volume 125, Issue 5, 2 June 2006, Pages 903-914
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Article
Structural Features of the GroEL-GroES Nano-Cage Required for Rapid Folding of Encapsulated Protein

https://doi.org/10.1016/j.cell.2006.04.027Get rights and content
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Summary

GroEL and GroES form a chaperonin nano-cage for proteins up to ∼60 kDa to fold in isolation. Here we explored the structural features of the chaperonin cage critical for rapid folding of encapsulated substrates. Modulating the volume of the GroEL central cavity affected folding speed in accordance with confinement theory. Small proteins (∼30 kDa) folded more rapidly as the size of the cage was gradually reduced to a point where restriction in space slowed folding dramatically. For larger proteins (∼40–50 kDa), either expanding or reducing cage volume decelerated folding. Additionally, interactions with the C-terminal, mildly hydrophobic Gly-Gly-Met repeat sequences of GroEL protruding into the cavity, and repulsion effects from the negatively charged cavity wall were required for rapid folding of some proteins. We suggest that by combining these features, the chaperonin cage provides a physical environment optimized to catalyze the structural annealing of proteins with kinetically complex folding pathways.

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Present address: Center for Biological Sequence Analysis, BioCentrum, Technical University of Denmark, Kemitorvet 208, DK-2800 Lyngby, Denmark.