Protein folding in the cell: functions of two families of molecular chaperone, hsp 60 and TF55-TCP1

1993 ◽  
Vol 339 (1289) ◽  
pp. 313-326 ◽  
Keyword(s):  
Protein Folding ◽  
Mechanism Of Action ◽  
Molecular Chaperone ◽  
Polypeptide Chain ◽  
Family Members ◽  
Chain Folding ◽  
Cell Functions ◽  
Cellular Compartments

Two families of molecular chaperone, the hsp 60-GroEL family and the TF55-TCP1 family, have been discovered in evolutionarily related cellular compartments. A member of one of these families, hsp 60, has been shown to play a global role in polypeptide chain folding in mitochondria. We review here studies of both hsp 60 and other family members, discussing their essential physiological roles and mechanism of action.

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.

Genetic Analysis of Polypeptide Chain Folding and Misfolding in Vivo

1990 ◽  
pp. 59-78 ◽  
Author(s):  
Jonathan King ◽  
Ben Fane ◽  
Cameron Haase-Pettingell ◽  
Anna Mitraki ◽  
Robert Villafane
Keyword(s):  
Genetic Analysis ◽  
Polypeptide Chain ◽  
Chain Folding

scholarly journals Expression, purification, crystallization and X-ray diffraction studies of the molecular chaperone prefoldin fromHomo sapiens

2015 ◽  
Vol 71 (9) ◽  
pp. 1189-1193 ◽  
Author(s):  
Yoshiki Aikawa ◽  
Hiroshi Kida ◽  
Yuichi Nishitani ◽  
Kunio Miki
Keyword(s):  
Crystal Structure ◽  
Protein Folding ◽  
Diffraction Data ◽  
Molecular Chaperone ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Native Proteins ◽  
Group Ii Chaperonin

Proper protein folding is an essential process for all organisms. Prefoldin (PFD) is a molecular chaperone that assists protein folding by delivering non-native proteins to group II chaperonin. A heterohexamer of eukaryotic PFD has been shown to specifically recognize and deliver non-native actin and tubulin to chaperonin-containing TCP-1 (CCT), but the mechanism of specific recognition is still unclear. To determine its crystal structure, recombinant human PFD was reconstituted, purified and crystallized. X-ray diffraction data were collected to 4.7 Å resolution. The crystals belonged to space groupP21212, with unit-cell parametersa= 123.2,b= 152.4,c= 105.9 Å.

Insights into chaperonin function from studies on archaeal thermosomes

2011 ◽  
Vol 39 (1) ◽  
pp. 94-98 ◽  
Author(s):  
Peter Lund
Keyword(s):  
Cell Death ◽  
Protein Folding ◽  
Recent Work ◽  
Mechanism Of Action ◽  
Molecular Chaperones ◽  
Short Review ◽  
Living Cells ◽  
Living Organisms ◽  
Opening And Closing ◽  
Hydrolysis Of

It is now well understood that, although proteins fold spontaneously (in a thermodynamic sense), many nevertheless require the assistance of helpers called molecular chaperones to reach their correct and active folded state in living cells. This is because the pathways of protein folding are full of traps for the unwary: the forces that drive proteins into their folded states can also drive them into insoluble aggregates, and, particularly when cells are stressed, this can lead, without prevention or correction, to cell death. The chaperonins are a family of molecular chaperones, practically ubiquitous in all living organisms, which possess a remarkable structure and mechanism of action. They act as nanoboxes in which proteins can fold, isolated from their environment and from other partners with which they might, with potentially deleterious consequences, interact. The opening and closing of these boxes is timed by the binding and hydrolysis of ATP. The chaperonins which are found in bacteria are extremely well characterized, and, although those found in archaea (also known as thermosomes) and eukaryotes have received less attention, our understanding of these proteins is constantly improving. This short review will summarize what we know about chaperonin function in the cell from studies on the archaeal chaperonins, and show how recent work is improving our understanding of this essential class of molecular chaperones.

scholarly journals Model of Early Stage Intermediate in Respect to Its Final Structure

Biomolecules ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 866 ◽  
Author(s):  
Piotr Fabian ◽  
Katarzyna Stapor ◽  
Irena Roterman
Keyword(s):  
Protein Folding ◽  
Contingency Table ◽  
Polypeptide Chain ◽  
Early Stage ◽  
Probability Distributions ◽  
Hydrophobic Core ◽  
Structural Form ◽  
The Status ◽  
The Relationship ◽  
Structural Code

The model, describing a method of determining the structure of an early intermediate in the process of protein folding to analyze nonredundant PDB protein bases, allows determining the relationship between the sequence of tetrapeptides and their structural forms expressed by structural codes. The contingency table expressing such a relationship can be used to predict the structure of polypeptides by proposing a structural form with a precision limited to the structural code. However, by analyzing structural forms in native forms of proteins based on the fuzzy oil drop model, one can also determine the status of polypeptide chain fragments with respect to the assumptions of this model. Whether the probability distributions for both compliant and noncompliant forms were similar or whether the tetrapeptide sequences showed some differences at a level of a set of structural codes was investigated. The analysis presented here indicated that some sequences in both forms revealed differences in probability distributions expressed as a negative statistically significant correlation coefficient. This meant that the identified sections (tetrapeptides) took different forms against the fuzzy oil drop model. It may suggest that the information of the final status with respect to hydrophobic core formation is already carried by the structure of the early-stage intermediate.

scholarly journals Chaperoning ribosome assembly

2010 ◽  
Vol 189 (1) ◽  
pp. 11-12 ◽  
Author(s):  
Katrin Karbstein
Keyword(s):  
Protein Folding ◽  
Ribosome Assembly ◽  
Cell Biol ◽  
Nascent Chain ◽  
Cellular Compartments

Chaperones help proteins fold in all cellular compartments, and many associate directly with ribosomes, capturing nascent chains to assist their folding and prevent aggregation. In this issue, new data from Koplin et al. (2010. J. Cell Biol. doi: 10.1083/jcb.200910074) and Albanèse et al. (2010. J. Cell Biol. doi: 10.1083/jcb.201001054) suggest that in addition to promoting protein folding, the chaperones ribosome-associated complex (RAC), nascent chain–associated complex (NAC), and Jjj1 also help in the assembly of ribosomes.

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