scholarly journals Multivalent Binding of Nonnative Substrate Proteins by the Chaperonin GroEL

Cell ◽  
2000 ◽  
Vol 100 (5) ◽  
pp. 561-573 ◽  
Author(s):  
George W Farr ◽  
Krystyna Furtak ◽  
Matthew B Rowland ◽  
Neil A Ranson ◽  
Helen R Saibil ◽  
...  
Keyword(s):  
Chaperonin Groel ◽  
Multivalent Binding ◽  
Substrate Proteins

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.

Mechanism of substrate recognition by the chaperonin GroEL

2001 ◽  
Vol 79 (5) ◽  
pp. 569-577 ◽  
Author(s):  
Walid A Houry
Keyword(s):  
Substrate Recognition ◽  
Dependent Manner ◽  
Molecular Weight Range ◽  
Hydrophobic Residues ◽  
Chaperonin Groel ◽  
Wide Range ◽  
Preferential Binding ◽  
Β Sheets ◽  
Substrate Proteins

The bacterial chaperonin GroEL functions with its cofactor GroES in assisting the folding of a wide range of proteins in an ATP-dependent manner. GroEL–GroES constitute one of the main chaperone systems in the Escherichia coli cytoplasm. The chaperonin facilitates protein folding by enclosing substrate proteins in a cage defined by the GroEL cylinder and the GroES cap where folding can take place in a protected environment. The in vivo role of GroEL has recently been elucidated. GroEL is found to interact with 10–15% of newly synthesized proteins, with a strong preference for proteins in the molecular weight range of 20–60 kDa. A large number of GroEL substrates have been identified and were found to preferentially contain proteins with multiple αβ domains that have α-helices and β-sheets with extensive hydrophobic surfaces. Based on the preferential binding of GroEL to these proteins and structural and biochemical data, a model of substrate recognition by GroEL is proposed. According to this model, binding takes place preferentially between the hydrophobic residues in the apical domains of GroEL and the hydrophobic faces exposed by the β-sheets or α-helices in the αβ domains of protein substrates.Key words: chaperone, folding, binding, hydrophobic interaction, structure.

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.

High-resolution gold labeling

1993 ◽  
Vol 51 ◽  
pp. 330-331
Author(s):  
James F. Hainfeld ◽  
Frederic R. Furuya ◽  
Kyra Carbone ◽  
Martha Simon ◽  
Beth Lin ◽  
...  
Keyword(s):  
Dihydrofolate Reductase ◽  
Polypeptide Chain ◽  
External Surface ◽  
Gold Cluster ◽  
Macromolecular Complex ◽  
Gold Compound ◽  
Central Cavity ◽  
Chain Folding ◽  
E Coli ◽  
Chaperonin Groel

A recently developed 1.4 nm gold cluster has been found to be useful in labeling macromolecular sites to 1-3 nm resolution. The gold compound is organically derivatized to contain a monofunctional arm for covalent linking to biomolecules. This may be used to mark a specific site on a structure, or to first label a component and then reassemble a multicomponent macromolecular complex. Two examples are given here: the chaperonin groEL and ribosomes.Chaperonins are essential oligomeric complexes that mediate nascent polypeptide chain folding to produce active proteins. The E. coli chaperonin, groEL, has two stacked rings with a central hole ∽6 nm in diameter. The protein dihydrofolate reductase (DHFR) is a small protein that has been used in chain folding experiments, and serves as a model substrate for groEL. By labeling the DHFR with gold, its position with respect to the groEL complex can be followed. In particular, it was sought to determine if DHFR refolds on the external surface of the groEL complex, or whether it interacts in the central cavity.

scholarly journals Mechanism of the small ATP-independent chaperone Spy is substrate specific

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rishav Mitra ◽  
Varun V. Gadkari ◽  
Ben A. Meinen ◽  
Carlo P. M. van Mierlo ◽  
Brandon T. Ruotolo ◽  
...  
Keyword(s):  
Relative Affinity ◽  
Complex Protein ◽  
Partially Unfolded ◽  
Substrate Proteins ◽  
Partially Unfolded States

AbstractATP-independent chaperones are usually considered to be holdases that rapidly bind to non-native states of substrate proteins and prevent their aggregation. These chaperones are thought to release their substrate proteins prior to their folding. Spy is an ATP-independent chaperone that acts as an aggregation inhibiting holdase but does so by allowing its substrate proteins to fold while they remain continuously chaperone bound, thus acting as a foldase as well. The attributes that allow such dual chaperoning behavior are unclear. Here, we used the topologically complex protein apoflavodoxin to show that the outcome of Spy’s action is substrate specific and depends on its relative affinity for different folding states. Tighter binding of Spy to partially unfolded states of apoflavodoxin limits the possibility of folding while bound, converting Spy to a holdase chaperone. Our results highlight the central role of the substrate in determining the mechanism of chaperone action.

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