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  Chaperonin-Assisted Protein Folding: Relative Population of Asymmetric and Symmetric GroEL:GroES Complexes

Haldar, S., Gupta, A. J., Yan, X., Milicic, G., Hartl, F. U., & Hayer-Hartl, M. (2015). Chaperonin-Assisted Protein Folding: Relative Population of Asymmetric and Symmetric GroEL:GroES Complexes. JOURNAL OF MOLECULAR BIOLOGY, 427(12), 2244-2255. doi:10.1016/j.jmb.2015.04.009.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-002A-19DA-A Version Permalink: http://hdl.handle.net/11858/00-001M-0000-002A-19DB-8
Genre: Journal Article

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 Creators:
Haldar, Shubhasis1, Author              
Gupta, Amit J.1, Author              
Yan, Xiao1, Author              
Milicic, Goran1, Author              
Hartl, F. Ulrich1, Author              
Hayer-Hartl, Manajit2, Author              
Affiliations:
1Hartl, Franz-Ulrich / Cellular Biochemistry, Max Planck Institute of Biochemistry, Max Planck Society, ou_1565152              
2Hayer-Hartl, Manajit / Chaperonin-assisted Protein Folding, Max Planck Institute of Biochemistry, Max Planck Society, ou_1565153              

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Free keywords: REACTION CYCLE; ATPASE CYCLE; SUBSTRATE PROTEIN; CRYSTAL-STRUCTURE; GROE CHAPERONINS; INTERMEDIATE; MECHANISM; RINGS; PROTEOSTASIS; ALLOSTERYchaperonin; GroEL; GroES; protein folding; fluorescence correlation spectroscopy;
 Abstract: The chaperonin GroEL, a cylindrical complex consisting of two stacked heptameric rings, and its lid-like cofactor GroES form a nano-cage in which a single polypeptide chain is transiently enclosed and allowed to fold unimpaired by aggregation. GroEL and GroES undergo an ATP-regulated interaction cycle that serves to close and open the folding cage. Recent reports suggest that the presence of non-native substrate protein alters the GroEL/ES reaction by shifting it from asymmetric to symmetric complexes. In the asymmetric reaction mode, only one ring of GroEL is GroES bound and the two rings function sequentially, coupled by negative allostery. In the symmetric mode, both GroEL rings are GroES bound and are folding active simultaneously. Here, we find that the results of assays based on fluorescence resonance energy transfer recently used to quantify symmetric complexes depend strongly on the fluorophore pair used. We therefore developed a novel assay based on fluorescence cross-correlation spectroscopy to accurately measure GroEL:GroES stoichiometry. This assay avoids fluorophore labeling of GroEL and the use of GroEL cysteine mutants. Our results show that symmetric GroEL:GroES(2) complexes are substantially populated only in the presence of non-foldable model proteins, such as alpha-lactalbumin and a-casein, which "over-stimulate" the GroEL ATPase and uncouple the negative GroEL inter-ring allostery. In contrast, asymmetric complexes are dominant both in the absence of substrate and in the presence of foldable substrate proteins. Moreover, uncoupling of the GroEL rings and formation of symmetric GroEL:GroES2 complexes is suppressed at physiological ATP:ADP concentration. We conclude that the asymmetric GroEL:GroES complex represents the main folding active form of the chaperonin. (C) 2015 Elsevier Ltd. All rights reserved.

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Language(s): eng - English
 Dates: 2015
 Publication Status: Published in print
 Pages: 12
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: ISI: 000356113000009
DOI: 10.1016/j.jmb.2015.04.009
 Degree: -

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Title: JOURNAL OF MOLECULAR BIOLOGY
Source Genre: Journal
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Publ. Info: 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
Pages: - Volume / Issue: 427 (12) Sequence Number: - Start / End Page: 2244 - 2255 Identifier: ISSN: 0022-2836