Cotranslational folding of proteins

1995 ◽  
Vol 73 (11-12) ◽  
pp. 1217-1220 ◽  
Author(s):  
Vyacheslav A. Kolb ◽  
Eugeny V. Makeyev ◽  
Aigar Kommer ◽  
Alexander S. Spirin
Keyword(s):  
Protein Folding ◽  
Biological Activity ◽  
Molecular Chaperones ◽  
Mature Protein ◽  
Native Structure ◽  
Folding Process ◽  
Cotranslational Folding

Many unfolded polypeptides are capable of refolding into their native structure upon the removal of the denaturant. However, the folding of the mature protein during renaturation does not accurately reflect the folding process of nascent proteins in the interior of the cell. This view resulted from the discovery of molecular chaperones known to modulate protein folding. Recent publications discussing the possible role and mechanisms of chaperone action suggest that folding in vivo may be a posttranslational process. Here we discuss data that indicate the final native structure and biological activity can be attainted by nascent protein on the ribosome, thus supporting the cotranslational folding hypothesis.Key words: nacent peptide, globin, luciferase, folding.

What does protein refolding in vitro tell us about protein folding in the cell?

1993 ◽  
Vol 339 (1289) ◽  
pp. 287-295 ◽  
Keyword(s):  
Protein Folding ◽  
Molecular Chaperones ◽  
Side Reaction ◽  
Kinetic Mechanism ◽  
Structural Elements ◽  
Native Structure ◽  
Extrinsic Factors ◽  
Structure Of Proteins

The classical in vitro denaturation-renaturation studies by Anson, Anfinsen, Neurath, Pauling and others clearly suggested that the primary structure of proteins determines all higher levels of protein structure. Protein folding in the cell is inaccessible to a detailed analysis of its kinetic mechanism. There are obvious differences: nascent proteins acquire their native structure co- and post-translationally, with half-times in the minutes range, whereas refolding starts from the complete polypeptide chain, with rates varying from seconds to days. In the cell, accessory proteins are involved in regulating the rate of folding and association. Their role can be analysed both in vivo , by mutant studies, or by coexpression together with recombinant model proteins, and in vitro , by folding experiments in the absence and in the presence of 'foldases’ and molecular chaperones, with the following general results: (i) folding is a sequential process involving native-like structural elements and a ‘collapsed state’ as early intermediates; (ii) the major side-reaction is caused by ‘kinetic partitioning’ between correct folding and wrong aggregation; (iii) rate-determining steps may be assisted by protein disulphide isomerase, peptidyl prolyl- cys - trans -isomerase, and molecular chaperones; and (iv) extrinsic factors, not encoded in the amino acid sequence, may be of crucial importance.

scholarly journals Unfolding the chaperone story

2017 ◽  
Vol 28 (22) ◽  
pp. 2919-2923 ◽  
Author(s):  
F. Ulrich Hartl
Keyword(s):  
Protein Folding ◽  
Molecular Chaperones ◽  
Current Concept ◽  
Cellular Process ◽  
Protein Chain ◽  
Native State ◽  
Folding Process ◽  
Spontaneous Process ◽  
Short Essay

Protein folding in the cell was originally assumed to be a spontaneous process, based on Anfinsen’s discovery that purified proteins can fold on their own after removal from denaturant. Consequently cell biologists showed little interest in the protein folding process. This changed only in the mid and late 1980s, when the chaperone story began to unfold. As a result, we now know that in vivo, protein folding requires assistance by a complex machinery of molecular chaperones. To ensure efficient folding, members of different chaperone classes receive the nascent protein chain emerging from the ribosome and guide it along an ordered pathway toward the native state. I was fortunate to contribute to these developments early on. In this short essay, I will describe some of the critical steps leading to the current concept of protein folding as a highly organized cellular process.

Principles of chaperone-mediated protein folding

1995 ◽  
Vol 348 (1323) ◽  
pp. 107-112 ◽  
Keyword(s):  
Protein Folding ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Molecular Chaperones ◽  
Cellular Protein ◽  
Chaperone Proteins ◽  
Shock Proteins ◽  
Polypeptide Chains

The recent discovery of molecular chaperones and their functions has changed dramatically our view of the processes underlying the folding of proteins in vivo . Rather than folding spontaneously, most newly synthesized polypeptide chains seem to acquire their native conformations in a reaction mediated by chaperone proteins. Different classes of molecular chaperones, such as the members of the Hsp70 and Hsp60 families of heat-shock proteins, cooperate in a coordinated pathway of cellular protein folding.

scholarly journals Cotranslational protein folding can promote the formation of correct folding intermediate

2020 ◽  
Author(s):  
P. Tao ◽  
Y. Xiao
Keyword(s):  
Molecular Dynamics ◽  
Protein Folding ◽  
Molecular Dynamics Simulations ◽  
General Scheme ◽  
Folding Intermediate ◽  
Microscopic Mechanism ◽  
Cotranslational Folding ◽  
Exit Tunnel ◽  
Dynamics Simulations

AbstractCotranslational folding is vital for proteins to form correct structures in vivo. However, it is still unclear how a nascent chain folds at atomic resolution during the translation process. Previously, we have built a model of ribosomal exit tunnel and investigated cotranslational folding of a three-helices protein by using all-atom molecular dynamics simulations. Here we shall study the cotranslational folding of three mainly-β proteins using the same method and find that cotranslational folding can enhance helical population in most cases and reduce nonnative long-range contacts before emerging from the ribosomal exit tunnel. After exiting the tunnel, all proteins fall into local minimal states and structural ensembles in cotranslational folding are more helical than in free folding. Importantly, for GTT WW domain, one local minimal state in cotranslational folding is known as correct folding intermediate, which is not found in free folding. This result suggests that cotranslational folding may directly increase folding efficiency by accelerating sampling more than by avoiding the misfolded state, which is a mainstream viewpoint in present. In addition, our method can serve as a general scheme to study cotranslational folding process of proteins.Statement of SignificanceIn cell, the formations of correct three-dimensional structures of proteins, namely protein folding, are essential to human health. Misfolding can lead to serious diseases such as Alzheimer’s disease and mad cow disease. As the first step of in vivo folding, the effect of cotranslational folding on the correct folding of proteins has been the focus of scientific research in this century. Although some experiments have shown that cotranslational folding can improve the efficiency of folding, its microscopic mechanism is not yet clear. In this paper, we study the process of cotranslational folding of three proteins by using all-atom molecular dynamics simulations, and try to reveal some aspects of the mechanism of cotranslational folding from a microscopic perspective.

scholarly journals GroEL/ES buffers entropic traps in folding pathway during evolution of a model substrate

2020 ◽  
Author(s):  
Anwar Sadat ◽  
Satyam Tiwari ◽  
Kanika Verma ◽  
Arjun Ray ◽  
Mudassar Ali ◽  
...  
Keyword(s):  
Protein Folding ◽  
Molecular Chaperones ◽  
Folding Pathway ◽  
Substrate Protein ◽  
Model Protein ◽  
Physical Barriers ◽  
Evolutionary Step ◽  
Entropic Traps

ABSTRACTThe folding landscape of proteins can change during evolution with the accumulation of mutations that may introduce entropic or enthalpic barriers in the protein folding pathway, making it a possible substrate of molecular chaperones in vivo. Can the nature of such physical barriers of folding dictate the feasibility of chaperone-assistance? To address this, we have simulated the evolutionary step to chaperone-dependence keeping GroEL/ES as the target chaperone and GFP as a model protein in an unbiased screen. We find that the mutation conferring GroEL/ES dependence in vivo and in vitro encode an entropic trap in the folding pathway rescued by the chaperonin. Additionally, GroEL/ES can edit the formation of non-native contacts similar to DnaK/J/E machinery. However, this capability is not utilized by the substrates in vivo. As a consequence, GroEL/ES caters to buffer mutations that predominantly cause entropic traps, despite possessing the capacity to edit both enthalpic and entropic traps in the folding pathway of the substrate protein.

scholarly journals The Complex Phosphorylation Patterns that Regulate the Activity of Hsp70 and Its Cochaperones

2019 ◽  
Vol 20 (17) ◽  
pp. 4122 ◽  
Author(s):  
Velasco ◽  
Dublang ◽  
Moro ◽  
Muga
Keyword(s):  
Biological Activity ◽  
Molecular Chaperones ◽  
Acute Stress ◽  
Phosphorylation Sites ◽  
Native Structure ◽  
Post Translational Modifications ◽  
Cytotoxic Cells ◽  
Functional Consequences ◽  
Client Proteins ◽  
Human Hsp70

Proteins must fold into their native structure and maintain it during their lifespan to display the desired activity. To ensure proper folding and stability, and avoid generation of misfolded conformations that can be potentially cytotoxic, cells synthesize a wide variety of molecular chaperones that assist folding of other proteins and avoid their aggregation, which unfortunately is unavoidable under acute stress conditions. A protein machinery in metazoa, composed of representatives of the Hsp70, Hsp40, and Hsp110 chaperone families, can reactivate protein aggregates. We revised herein the phosphorylation sites found so far in members of these chaperone families and the functional consequences associated with some of them. We also discuss how phosphorylation might regulate the chaperone activity and the interaction of human Hsp70 with its accessory and client proteins. Finally, we present the information that would be necessary to decrypt the effect that post-translational modifications, and especially phosphorylation, could have on the biological activity of the Hsp70 system, known as the “chaperone code”.

scholarly journals Quantitative determination of ribosome nascent chain stability

2016 ◽  
Vol 113 (47) ◽  
pp. 13402-13407 ◽  
Author(s):  
Avi J. Samelson ◽  
Madeleine K. Jensen ◽  
Randy A. Soto ◽  
Jamie H. D. Cate ◽  
Susan Marqusee
Keyword(s):  
Protein Folding ◽  
Energy Landscape ◽  
Cell Protein ◽  
Folding Process ◽  
Cellular Processes ◽  
Additional Layer ◽  
Biophysical Studies ◽  
Nascent Chain

Accurate protein folding is essential for proper cellular and organismal function. In the cell, protein folding is carefully regulated; changes in folding homeostasis (proteostasis) can disrupt many cellular processes and have been implicated in various neurodegenerative diseases and other pathologies. For many proteins, the initial folding process begins during translation while the protein is still tethered to the ribosome; however, most biophysical studies of a protein’s energy landscape are carried out in isolation under idealized, dilute conditions and may not accurately report on the energy landscape in vivo. Thus, the energy landscape of ribosome nascent chains and the effect of the tethered ribosome on nascent chain folding remain unclear. Here we have developed a general assay for quantitatively measuring the folding stability of ribosome nascent chains, and find that the ribosome exerts a destabilizing effect on the polypeptide chain. This destabilization decreases as a function of the distance away from the peptidyl transferase center. Thus, the ribosome may add an additional layer of robustness to the protein-folding process by avoiding the formation of stable partially folded states before the protein has completely emerged from the ribosome.

scholarly journals Functional Subunits of Eukaryotic Chaperonin CCT/TRiC in Protein Folding

2011 ◽  
Vol 2011 ◽  
pp. 1-16 ◽  
Author(s):  
M. Anaul Kabir ◽  
Wasim Uddin ◽  
Aswathy Narayanan ◽  
Praveen Kumar Reddy ◽  
M. Aman Jairajpuri ◽  
...  
Keyword(s):  
Protein Folding ◽  
Molecular Chaperones ◽  
Electrostatic Interactions ◽  
Fine Tuning ◽  
Cellular Proteins ◽  
Dependent Manner ◽  
Central Cavity ◽  
Folding Process ◽  
Nonspecific Interactions ◽  
Catalytic Cooperativity

Molecular chaperones are a class of proteins responsible for proper folding of a large number of polypeptides in both prokaryotic and eukaryotic cells. Newly synthesized polypeptides are prone to nonspecific interactions, and many of them make toxic aggregates in absence of chaperones. The eukaryotic chaperonin CCT is a large, multisubunit, cylindrical structure having two identical rings stacked back to back. Each ring is composed of eight different but similar subunits and each subunit has three distinct domains. CCT assists folding of actin, tubulin, and numerous other cellular proteins in an ATP-dependent manner. The catalytic cooperativity of ATP binding/hydrolysis in CCT occurs in a sequential manner different from concerted cooperativity as shown for GroEL. Unlike GroEL, CCT does not have GroES-like cofactor, rather it has a built-in lid structure responsible for closing the central cavity. The CCT complex recognizes its substrates through diverse mechanisms involving hydrophobic or electrostatic interactions. Upstream factors like Hsp70 and Hsp90 also work in a concerted manner to transfer the substrate to CCT. Moreover, prefoldin, phosducin-like proteins, and Bag3 protein interact with CCT and modulate its function for the fine-tuning of protein folding process. Any misregulation of protein folding process leads to the formation of misfolded proteins or toxic aggregates which are linked to multiple pathological disorders.

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