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The mechanism of GroEL/GroES folding/refolding of protein substrates revisited.
Org Biomol Chem. 2006 Apr 07; 4(7):1223-35.OB

Abstract

The thermodynamics and kinetics of zinc-cytochrome c (ZnCyt c) interactions with Escherichia coli molecular chaperone GroEL (Chaperonin 60; Cpn60) are described. Zinc(II)-porphyrin represents a flexible fluorescent probe for thermodynamic complex formation between GroEL and ZnCyt c, as well as for stopped-flow fluorescence kinetic experiments. Data suggests that GroEL and GroEL/GroES-assisted refolding of unfolded ZnCyt c takes place by a mechanism that is quite close to the Anfinsen Cage hypothesis for molecular chaperone activity. However, even in the presence of ATP, GroEL/GroES-assisted refolding of ZnCyt c takes place at approximately half the rate of refolding of ZnCyt c alone. On the other hand, there is little evidence for refolding behaviour consistent with the Iterative Annealing hypothesis. This includes a complete lack of GroEL or GroEL/GroES-assisted enhancement of refolding rate constant k(2) associated with the unfolding of a putative misfolded state I (Zn) on the pathway to the native state. Reviewing our data in the light of data from other laboratories, we observe that all forward rate enhancements or reductions could be accounted for in terms of thermodynamic coupling (adjusting positions of refolding equilibria) due to binding interactions between GroEL and unfolded protein substrates, driven by thermodynamic considerations. Therefore, we propose that passive kinetic partitioning should be considered the core mechanism of the GroEL/GroES molecular chaperone machinery, wherein the core function is to bind unfolded protein substrates leading to a blockade of aggregation pathways and to increases in molecular flux through productive folding pathway(s).

Authors+Show Affiliations

Imperial College Genetic Therapies Centre, Department of Chemistry Imperial College London, Flowers Building, Armstrong Road, Imperial College London, London, UKSW7 2AZ.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16557310

Citation

Jones, Huw, et al. "The Mechanism of GroEL/GroES Folding/refolding of Protein Substrates Revisited." Organic & Biomolecular Chemistry, vol. 4, no. 7, 2006, pp. 1223-35.
Jones H, Preuss M, Wright M, et al. The mechanism of GroEL/GroES folding/refolding of protein substrates revisited. Org Biomol Chem. 2006;4(7):1223-35.
Jones, H., Preuss, M., Wright, M., & Miller, A. D. (2006). The mechanism of GroEL/GroES folding/refolding of protein substrates revisited. Organic & Biomolecular Chemistry, 4(7), 1223-35.
Jones H, et al. The Mechanism of GroEL/GroES Folding/refolding of Protein Substrates Revisited. Org Biomol Chem. 2006 Apr 7;4(7):1223-35. PubMed PMID: 16557310.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The mechanism of GroEL/GroES folding/refolding of protein substrates revisited. AU - Jones,Huw, AU - Preuss,Monika, AU - Wright,Michael, AU - Miller,Andrew D, Y1 - 2006/03/03/ PY - 2006/3/25/pubmed PY - 2007/8/31/medline PY - 2006/3/25/entrez SP - 1223 EP - 35 JF - Organic & biomolecular chemistry JO - Org Biomol Chem VL - 4 IS - 7 N2 - The thermodynamics and kinetics of zinc-cytochrome c (ZnCyt c) interactions with Escherichia coli molecular chaperone GroEL (Chaperonin 60; Cpn60) are described. Zinc(II)-porphyrin represents a flexible fluorescent probe for thermodynamic complex formation between GroEL and ZnCyt c, as well as for stopped-flow fluorescence kinetic experiments. Data suggests that GroEL and GroEL/GroES-assisted refolding of unfolded ZnCyt c takes place by a mechanism that is quite close to the Anfinsen Cage hypothesis for molecular chaperone activity. However, even in the presence of ATP, GroEL/GroES-assisted refolding of ZnCyt c takes place at approximately half the rate of refolding of ZnCyt c alone. On the other hand, there is little evidence for refolding behaviour consistent with the Iterative Annealing hypothesis. This includes a complete lack of GroEL or GroEL/GroES-assisted enhancement of refolding rate constant k(2) associated with the unfolding of a putative misfolded state I (Zn) on the pathway to the native state. Reviewing our data in the light of data from other laboratories, we observe that all forward rate enhancements or reductions could be accounted for in terms of thermodynamic coupling (adjusting positions of refolding equilibria) due to binding interactions between GroEL and unfolded protein substrates, driven by thermodynamic considerations. Therefore, we propose that passive kinetic partitioning should be considered the core mechanism of the GroEL/GroES molecular chaperone machinery, wherein the core function is to bind unfolded protein substrates leading to a blockade of aggregation pathways and to increases in molecular flux through productive folding pathway(s). SN - 1477-0520 UR - https://www.unboundmedicine.com/medline/citation/16557310/The_mechanism_of_GroEL/GroES_folding/refolding_of_protein_substrates_revisited_ DB - PRIME DP - Unbound Medicine ER -