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ATP-triggered conformational changes delineate substrate-binding and -folding mechanics of the GroEL Chaperonin

Clare, Daniel K. and Vasishtan, Daven and Stagg, S. and Quispe, J. and Farr, G.W. and Topf, Maya and Horwich, A.L. and Saibil, Helen R. (2012) ATP-triggered conformational changes delineate substrate-binding and -folding mechanics of the GroEL Chaperonin. Cell 149 (1), pp. 113-123. ISSN 0092-8674.

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Official URL: http://dx.doi.org/10.1016/j.cell.2012.02.047

Abstract

The chaperonin GroEL assists the folding of nascent or stress-denatured polypeptides by actions of binding and encapsulation. ATP binding initiates a series of conformational changes triggering the association of the cochaperonin GroES, followed by further large movements that eject the substrate polypeptide from hydrophobic binding sites into a GroES-capped, hydrophilic folding chamber. We used cryo-electron microscopy, statistical analysis, and flexible fitting to resolve a set of distinct GroEL-ATP conformations that can be ordered into a trajectory of domain rotation and elevation. The initial conformations are likely to be the ones that capture polypeptide substrate. Then the binding domains extend radially to separate from each other but maintain their binding surfaces facing the cavity, potentially exerting mechanical force upon kinetically trapped, misfolded substrates. The extended conformation also provides a potential docking site for GroES, to trigger the final, 100° domain rotation constituting the “power stroke” that ejects substrate into the folding chamber.

Item Type: Article
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 23 Mar 2012 09:40
Last Modified: 17 Apr 2013 12:22
URI: http://eprints.bbk.ac.uk/id/eprint/4660

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