scholarly journals Chaperonin facilitates protein folding by avoiding polypeptide collapse

2017 ◽  
Author(s):  
Fumihiro Motojima ◽  
Katsuya Fujii ◽  
Masasuke Yoshida
Keyword(s):  
Protein Folding ◽  
Cell Viability ◽  
Cellular Proteins ◽  
Intermediate Complex ◽  
Essential Proteins ◽  
Denatured Protein ◽  
Chaperonin Groel ◽  
Show Evidence ◽  
Acceleration And Deceleration ◽  
Substrate Proteins

AbstractChaperonins assist folding of many cellular proteins, including essential proteins for cell viability. However, it remains unclear how chaperonin-assisted folding is different from spontaneous folding. Chaperonin GroEL/GroES facilitates folding of denatured protein encapsulated in its central cage but the denatured protein often escapes from the cage to the outside during reaction. Here, we show evidence that the in-cage-folding and the escape occur diverging from the same intermediate complex in which polypeptide is tethered loosely to the cage and partly protrudes out of the cage. Furthermore, denatured proteins in the chaperonin cage start their folding from extended conformations but not from compact conformations as usually observed in spontaneous folding. We propose that the formation of tethered intermediate of polypeptide is necessary to prevent polypeptide collapse at the expense of polypeptide escape. The tethering of polypeptide would allow freely mobile portions of tethered polypeptide to fold segmentally. The folding acceleration and deceleration by chaperonin for various substrate proteins can be explained by considering the tethering.

scholarly journals Back to GroEL-Assisted Protein Folding: GroES Binding-Induced Displacement of Denatured Proteins from GroEL to Bulk Solution

Biomolecules ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 162
Author(s):  
Victor Marchenkov ◽  
Andrey Gorokhovatsky ◽  
Natalia Marchenko ◽  
Tanya Ivashina ◽  
Gennady Semisotnov
Keyword(s):  
Protein Folding ◽  
Serum Albumin ◽  
Malate Dehydrogenase ◽  
Bulk Solution ◽  
Stopped Flow ◽  
Denatured Protein ◽  
Neutral Ph ◽  
Denatured Proteins ◽  
Native Electrophoresis ◽  
Substrate Proteins

The main events in chaperone-assisted protein folding are the binding and ligand-induced release of substrate proteins. Here, we studied the location of denatured proteins previously bound to the GroEL chaperonin resulting from the action of the GroES co-chaperonin in the presence of Mg-ATP. Fluorescein-labeled denatured proteins (α-lactalbumin, lysozyme, serum albumin, and pepsin in the presence of thiol reagents at neutral pH, as well as an early refolding intermediate of malate dehydrogenase) were used to reveal the effect of GroES on their interaction with GroEL. Native electrophoresis has demonstrated that these proteins tend to be released from the GroEL-GroES complex. With the use of biotin- and fluorescein-labeled denatured proteins and streptavidin fused with luciferase aequorin (the so-called streptavidin trap), the presence of denatured proteins in bulk solution after GroES and Mg-ATP addition has been confirmed. The time of GroES-induced dissociation of a denatured protein from the GroEL surface was estimated using the stopped-flow technique and found to be much shorter than the proposed time of the GroEL ATPase cycle.

scholarly journals Balanced Ero1 activation and inactivation establishes ER redox homeostasis

2012 ◽  
Vol 196 (6) ◽  
pp. 713-725 ◽  
Author(s):  
Sunghwan Kim ◽  
Dionisia P. Sideris ◽  
Carolyn S. Sevier ◽  
Chris A. Kaiser
Keyword(s):  
Protein Folding ◽  
Disulfide Bonds ◽  
Direct Reduction ◽  
Redox Homeostasis ◽  
Feedback Regulation ◽  
Redox Balance ◽  
Oxidative Protein Folding ◽  
Reduced And Oxidized Glutathione ◽  
Minimum Number ◽  
Substrate Proteins

The endoplasmic reticulum (ER) provides an environment optimized for oxidative protein folding through the action of Ero1p, which generates disulfide bonds, and Pdi1p, which receives disulfide bonds from Ero1p and transfers them to substrate proteins. Feedback regulation of Ero1p through reduction and oxidation of regulatory bonds within Ero1p is essential for maintaining the proper redox balance in the ER. In this paper, we show that Pdi1p is the key regulator of Ero1p activity. Reduced Pdi1p resulted in the activation of Ero1p by direct reduction of Ero1p regulatory bonds. Conversely, upon depletion of thiol substrates and accumulation of oxidized Pdi1p, Ero1p was inactivated by both autonomous oxidation and Pdi1p-mediated oxidation of Ero1p regulatory bonds. Pdi1p responded to the availability of free thiols and the relative levels of reduced and oxidized glutathione in the ER to control Ero1p activity and ensure that cells generate the minimum number of disulfide bonds needed for efficient oxidative protein folding.

Interaction of oxidized chaperonin GroEL with an unfolded protein at low temperatures

2012 ◽  
Vol 32 (3) ◽  
pp. 299-303 ◽  
Author(s):  
Girish C. Melkani ◽  
Robin Sielaff ◽  
Gustavo Zardeneta ◽  
Jose A. Mendoza
Keyword(s):  
Atpase Activity ◽  
Low Temperatures ◽  
Hydrophobic Interactions ◽  
Hydrophobic Surfaces ◽  
Unfolded Protein ◽  
Native Proteins ◽  
Chaperonin Groel ◽  
Excess Amount ◽  
Substrate Proteins

The chaperonin GroEL binds to non-native substrate proteins via hydrophobic interactions, preventing their aggregation, which is minimized at low temperatures. In the present study, we investigated the refolding of urea-denatured rhodanese at low temperatures, in the presence of ox-GroEL (oxidized GroEL), which contains increased exposed hydrophobic surfaces and retains its ability to hydrolyse ATP. We found that ox-GroEL could efficiently bind the urea-unfolded rhodanese at 4°C, without requiring excess amount of chaperonin relative to normal GroEL (i.e. non-oxidized). The release/reactivation of rhodanese from GroEL was minimal at 4°C, but was found to be optimal between 22 and 37°C. It was found that the loss of the ATPase activity of ox-GroEL at 4°C prevented the release of rhodanese from the GroEL–rhodanese complex. Thus ox-GroEL has the potential to efficiently trap recombinant or non-native proteins at 4°C and release them at higher temperatures under appropriate conditions.

Chaperonin-mediated protein folding: using a central cavity to kinetically assist polypeptide chain folding

2009 ◽  
Vol 42 (2) ◽  
pp. 83-116 ◽  
Author(s):  
Arthur L. Horwich ◽  
Wayne A. Fenton
Keyword(s):  
Protein Folding ◽  
Polypeptide Chain ◽  
Experimental Studies ◽  
Central Cavity ◽  
Hydrophobic Contact ◽  
Ring Assembly ◽  
Open Ring ◽  
The Subject ◽  
Kinetic Traps ◽  
Substrate Proteins

AbstractThe chaperonin ring assembly GroEL provides kinetic assistance to protein folding in the cell by binding non-native protein in the hydrophobic central cavity of an open ring and subsequently, upon binding ATP and the co-chaperonin GroES to the same ring, releasing polypeptide into a now hydrophilic encapsulated cavity where productive folding occurs in isolation. The fate of polypeptide during binding, encapsulation, and folding in the chamber has been the subject of recent experimental studies and is reviewed and considered here. We conclude that GroEL, in general, behaves passively with respect to its substrate proteins during these steps. While binding appears to be able to rescue non-native polypeptides from kinetic traps, such rescue is most likely exerted at the level of maximizing hydrophobic contact, effecting alteration of the topology of weakly structured states. Encapsulation does not appear to involve ‘forced unfolding’, and if anything, polypeptide topology is compacted during this step. Finally, chamber-mediated folding appears to resemble folding in solution, except that major kinetic complications of multimolecular association are prevented.

scholarly journals Strict experimental evidence that apo-chaperonin GroEL does not accelerate protein folding, although it does accelerate one of its steps

2015 ◽  
Vol 112 (50) ◽  
pp. E6831-E6832 ◽  
Author(s):  
Natalia Y. Marchenko ◽  
Victor V. Marchenkov ◽  
Gennady V. Semisotnov ◽  
Alexei V. Finkelstein
Keyword(s):  
Protein Folding ◽  
Experimental Evidence ◽  
Chaperonin Groel
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