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Multiple cycles of global unfolding of GroEL-bound cyclophilin A evidenced by NMR.
J Mol Biol. 1997 Sep 05; 271(5):803-18.JM

Abstract

GroE, the chaperonin system of Escherichia coli, prevents the aggregation of partially folded or misfolded proteins by complexing them in a form competent for subsequent folding to the native state. We examined the exchange of amide protons of cyclophilin A (CypA) interacting with GroEL, using NMR spectroscopy. We have applied labeling pulses in H2O to the deuterated GroEL-CypA-complex. When ATP and GroES were added after the labeling pulse, refolding of CypA could be accelerated to rates comparable to the amide proton exchange. This allowed the calculation of protection factors (PF) for the backbone amide protons in the GroEL-bound substrate protein. A set of highly protected protons in the native state (PF 10(5) to 10(7)) was observed to be much less protected (PF 10(2) to 10(4)) in complex with GroEL and, in contrast to the native structure, the protection factors were found to be quite uniform along the sequence suggesting that CypA with native-like structure undergoes multiple cycles of unfolding while bound to GroEL, which are faster than unfolding in free solution. Because of the small sequence dependence of the protection factors, unfolding must be global, and in this way the chaperone appears to resolve off-pathway intermediates and to support protein folding by annealing. Although in the complex with GroEL native-like states still predominate over globally unfolded states, this equilibrium is shifted 10(2) to 10(4)-fold toward the unfolded state when compared to CypA in free solution. Repeated global unfolding may be a key step in achieving a high yield of correctly folded proteins.

Authors+Show Affiliations

Biochemisches Institut der Universität Zürich, Winterthurerstr., Zürich, 190 8057, Switzerland.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

9299328

Citation

Nieba-Axmann, S E., et al. "Multiple Cycles of Global Unfolding of GroEL-bound Cyclophilin a Evidenced By NMR." Journal of Molecular Biology, vol. 271, no. 5, 1997, pp. 803-18.
Nieba-Axmann SE, Ottiger M, Wüthrich K, et al. Multiple cycles of global unfolding of GroEL-bound cyclophilin A evidenced by NMR. J Mol Biol. 1997;271(5):803-18.
Nieba-Axmann, S. E., Ottiger, M., Wüthrich, K., & Plückthun, A. (1997). Multiple cycles of global unfolding of GroEL-bound cyclophilin A evidenced by NMR. Journal of Molecular Biology, 271(5), 803-18.
Nieba-Axmann SE, et al. Multiple Cycles of Global Unfolding of GroEL-bound Cyclophilin a Evidenced By NMR. J Mol Biol. 1997 Sep 5;271(5):803-18. PubMed PMID: 9299328.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Multiple cycles of global unfolding of GroEL-bound cyclophilin A evidenced by NMR. AU - Nieba-Axmann,S E, AU - Ottiger,M, AU - Wüthrich,K, AU - Plückthun,A, PY - 1997/9/23/pubmed PY - 1997/9/23/medline PY - 1997/9/23/entrez SP - 803 EP - 18 JF - Journal of molecular biology JO - J Mol Biol VL - 271 IS - 5 N2 - GroE, the chaperonin system of Escherichia coli, prevents the aggregation of partially folded or misfolded proteins by complexing them in a form competent for subsequent folding to the native state. We examined the exchange of amide protons of cyclophilin A (CypA) interacting with GroEL, using NMR spectroscopy. We have applied labeling pulses in H2O to the deuterated GroEL-CypA-complex. When ATP and GroES were added after the labeling pulse, refolding of CypA could be accelerated to rates comparable to the amide proton exchange. This allowed the calculation of protection factors (PF) for the backbone amide protons in the GroEL-bound substrate protein. A set of highly protected protons in the native state (PF 10(5) to 10(7)) was observed to be much less protected (PF 10(2) to 10(4)) in complex with GroEL and, in contrast to the native structure, the protection factors were found to be quite uniform along the sequence suggesting that CypA with native-like structure undergoes multiple cycles of unfolding while bound to GroEL, which are faster than unfolding in free solution. Because of the small sequence dependence of the protection factors, unfolding must be global, and in this way the chaperone appears to resolve off-pathway intermediates and to support protein folding by annealing. Although in the complex with GroEL native-like states still predominate over globally unfolded states, this equilibrium is shifted 10(2) to 10(4)-fold toward the unfolded state when compared to CypA in free solution. Repeated global unfolding may be a key step in achieving a high yield of correctly folded proteins. SN - 0022-2836 UR - https://www.unboundmedicine.com/medline/citation/9299328/Multiple_cycles_of_global_unfolding_of_GroEL_bound_cyclophilin_A_evidenced_by_NMR_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0022-2836(97)91192-X DB - PRIME DP - Unbound Medicine ER -