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A mobile loop order–disorder transition modulates the speed of chaperonin cycling

Abstract

Molecular machines order and disorder polypeptides as they form and dissolve large intermolecular interfaces, but the biological significance of coupled ordering and binding has been established in few, if any, macromolecular systems. The ordering and binding of GroES co-chaperonin mobile loops accompany an ATP-dependent conformational change in the GroEL chaperonin that promotes client protein folding. Following ATP hydrolysis, disordering of the mobile loops accompanies co-chaperonin dissociation, reversal of the GroEL conformational change, and release of the client protein. "High-affinity" GroEL mutants were identified by their compatibility with "low-affinity" co-chaperonin mutants and incompatibility with high-affinity co-chaperonin mutants. Analysis of binding kinetics using the intrinsic fluorescence of tryptophan-containing co-chaperonin variants revealed that excessive affinity causes the chaperonin to stall in a conformation that forms in the presence of ATP. Destabilizing the beta-hairpins formed by the mobile loops restores the normal rate of dissociation. Thus, the free energy of mobile-loop ordering and disordering acts like the inertia of an engine's flywheel by modulating the speed of chaperonin conformational changes.

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Authors (6)

  • Photo of  Frank Shewmaker

    Frank Shewmaker

  • Photo of  Michael J. Kerner

    Michael J. Kerner

  • Photo of  Manajit Hayer-Hartl

    Manajit Hayer-Hartl

  • Photo of  Costa Georgopoulos

    Costa Georgopoulos

  • Photo of  Samuel J. Landry

    Samuel J. Landry

Keywords

Details

Category:
Articles
Type:
artykuły w czasopismach
Published in:
PROTEIN SCIENCE no. 13, pages 2139 - 2148,
ISSN: 0961-8368
Language:
English
Publication year:
2004
Bibliographic description:
Shewmaker F., Kerner M. J., Hayer-Hartl M., Klein-Raina G., Georgopoulos C., Landry S. J.: A mobile loop order–disorder transition modulates the speed of chaperonin cycling// PROTEIN SCIENCE -Vol. 13,iss. 8 (2004), s.2139-2148
DOI:
Digital Object Identifier (open in new tab) 10.1110/ps.04773204
Verified by:
Gdańsk University of Technology

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