Paradoxical Effects of Substitution and Deletion Mutation of Arg56 on the Structure and Chaperone Function of Human αB-Crystallin†

Biochemistry ◽  
2007 ◽  
Vol 46 (5) ◽  
pp. 1117-1127 ◽  
Author(s):  
Ashis Biswas ◽  
Jeffery Goshe ◽  
Antonia Miller ◽  
Puttur Santhoshkumar ◽  
Carol Luckey ◽  
...  
Keyword(s):  
Deletion Mutation ◽  
Chaperone Function ◽  
Paradoxical Effects ◽  
Αb Crystallin

scholarly journals Effect of Structural Changes Induced by Deletion of 54FLRAPSWF61 Sequence in αB-Crystallin on Chaperone Function and Anti-Apoptotic Activity

2021 ◽  
Vol 22 (19) ◽  
pp. 10771
Author(s):  
Sundararajan Mahalingam ◽  
Srabani Karmakar ◽  
Puttur Santhoshkumar ◽  
Krishna K. Sharma
Keyword(s):  
Deletion Mutant ◽  
Mutant Protein ◽  
Wild Type ◽  
Chaperone Function ◽  
Type Protein ◽  
Wild Type Protein ◽  
Cytotoxicity Studies ◽  
Αb Crystallin ◽  
Apoptotic Activity ◽  
Subunit Organization

Previously, we showed that the removal of the 54–61 residues from αB-crystallin (αBΔ54–61) results in a fifty percent reduction in the oligomeric mass and a ten-fold increase in chaperone-like activity. In this study, we investigated the oligomeric organization changes in the deletion mutant contributing to the increased chaperone activity and evaluated the cytoprotection properties of the mutant protein using ARPE-19 cells. Trypsin digestion studies revealed that additional tryptic cleavage sites become susceptible in the deletion mutant than in the wild-type protein, suggesting a different subunit organization in the oligomer of the mutant protein. Static and dynamic light scattering analyses of chaperone–substrate complexes showed that the deletion mutant has more significant interaction with the substrates than wild-type protein, resulting in increased binding of the unfolding proteins. Cytotoxicity studies carried out with ARPE-19 cells showed an enhancement in anti-apoptotic activity in αBΔ54–61 as compared with the wild-type protein. The improved anti-apoptotic activity of the mutant is also supported by reduced caspase activation and normalization of the apoptotic cascade components level in cells treated with the deletion mutant. Our study suggests that altered oligomeric assembly with increased substrate affinity could be the basis for the enhanced chaperone function of the αBΔ54–61 protein.

scholarly journals Single-molecule fluorescence-based approach reveals novel mechanistic insights into human small heat shock protein chaperone function

2020 ◽  
pp. jbc.RA120.015419
Author(s):  
Caitlin L Johnston ◽  
Nicholas R Marzano ◽  
Bishnu P Paudel ◽  
George Wright ◽  
Justin L.P. Benesch ◽  
...  
Keyword(s):  
Heat Shock ◽  
Single Molecule ◽  
Small Heat Shock Protein ◽  
Vital Role ◽  
Misfolded Proteins ◽  
Single Molecule Fluorescence ◽  
Chaperone Function ◽  
Αb Crystallin ◽  
Client Proteins ◽  
Shock Proteins

Small heat shock proteins (sHsps) are a family of ubiquitous intracellular molecular chaperones that are up-regulated under stress conditions and play a vital role in protein homeostasis (proteostasis). It is commonly accepted that these chaperones work by trapping misfolded proteins to prevent their aggregation; however, fundamental questions regarding the molecular mechanism by which sHsps interact with misfolded proteins remain unanswered. The dynamic and polydisperse nature of sHsp oligomers has made studying them challenging using traditional biochemical approaches. Therefore, we have utilized a single-molecule fluorescence-based approach to observe the chaperone action of human αB-crystallin (αBc, HSPB5). Using this approach we have, for the first time, determined the stoichiometries of complexes formed between αBc and a model client protein, chloride intracellular channel 1 (CLIC1). By examining the dispersity and stoichiometries of these complexes over time, and in response to different concentrations of αBc, we have uncovered unique and important insights into a two-step mechanism by which αBc interacts with misfolded client proteins to prevent their aggregation.

scholarly journals Insights into Hydrophobicity and the Chaperone-like Function of αA- and αB-crystallins

2005 ◽  
Vol 280 (23) ◽  
pp. 21726-21730 ◽  
Author(s):  
M. Satish Kumar ◽  
Mili Kapoor ◽  
Sharmistha Sinha ◽  
G. Bhanuprakash Reddy
Keyword(s):  
Binding Sites ◽  
Chaperone Activity ◽  
Titration Calorimetry ◽  
Affinity Binding ◽  
Hydrophobic Surfaces ◽  
Ans Binding ◽  
High Affinity Binding ◽  
Chaperone Function ◽  
High Affinity ◽  
Αb Crystallin

α-Crystallin, composed of two subunits, αA and αB, has been shown to function as a molecular chaperone that prevents aggregation of other proteins under stress conditions. The exposed hydrophobic surfaces of α-crystallins have been implicated in this process, but their exact role has not been elucidated. In this study, we quantify the hydrophobic surfaces of αA- and αB-crystallins by isothermal titration calorimetry using 8-anilino-1-napthalenesulfonic acid (ANS) as a hydrophobic probe and analyze its correlation to the chaperone potential of αA- and αB-crystallins under various conditions. Two ANS binding sites, one with low and another with high affinity, were clearly detected, with αB showing a higher number of sites than αA at 30 °C. In agreement with the higher number of hydrophobic sites, αB-crystallin demonstrated higher chaperone activity than αA at this temperature. Thermodynamic analysis of ANS binding to αA- and αB-crystallins indicates that high affinity binding is driven by both enthalpy and entropy changes, with entropy dominating the low affinity binding. Interestingly, although the number of ANS binding sites was similar for αA and αB at 15 °C, αA was more potent than αB in preventing aggregation of the insulin B-chain. Although there was no change in the number of high affinity binding sites of αA and αB for ANS upon preheating, there was an increase in the number of low affinity sites of αA and αB. Preheated αA, in contrast to αB, exhibited remarkably enhanced chaperone activity. Our results indicate that although hydrophobicity appears to be a factor in determining the chaperone-like activity of α-crystallins, it does not quantitatively correlate with the chaperone function of α-crystallins.

Chaperone function of mutant versions of αA- and αB-crystallin prepared to pinpoint chaperone binding sites

2001 ◽  
Vol 268 (3) ◽  
pp. 713-721 ◽  
Author(s):  
Barry K. Derham ◽  
Martinus A. M. van Boekel ◽  
Paul J. Muchowski ◽  
John I. Clark ◽  
Joseph Horwitz ◽  
...  
Keyword(s):  
Binding Sites ◽  
Chaperone Function ◽  
Αb Crystallin ◽  
Chaperone Binding

scholarly journals Single-molecule fluorescence-based approach reveals novel mechanistic insights into small heat shock protein chaperone function

2020 ◽  
Author(s):  
Caitlin L. Johnston ◽  
Nicholas R. Marzano ◽  
Bishnu Paudel ◽  
George Wright ◽  
Justin L. P. Benesch ◽  
...  
Keyword(s):  
Heat Shock ◽  
Single Molecule ◽  
Protein Misfolding ◽  
Protein Complexes ◽  
Small Heat Shock Protein ◽  
Vital Role ◽  
Misfolded Proteins ◽  
Single Molecule Fluorescence ◽  
Chaperone Function ◽  
Αb Crystallin

AbstractSmall heat shock proteins (sHsps) are a family of ubiquitous intracellular molecular chaperones that are up-regulated under stress conditions and play a vital role in protein homeostasis (proteostasis). It is commonly accepted that these chaperones work by trapping misfolded proteins to prevent their aggregation, however fundamental questions regarding the molecular mechanism by which sHsps interact with misfolded proteins remain unanswered. Traditionally, it has been difficult to study sHsp function due to the dynamic and heterogenous nature of the species formed between sHsps and aggregation-prone proteins. Single-molecule techniques have emerged as a powerful tool to study dynamic protein complexes and we have therefore developed a novel single-molecule fluorescence-based approach to observe the chaperone action of human αB-crystallin (αBc, HSPB5). Using this approach we have, for the first time, determined the stoichiometries of complexes formed between αBc and a model client protein, chloride intracellular channel 1 (CLIC1). By examining the polydispersity and stoichiometries of these complexes over time, and in response to different concentrations of αBc, we have uncovered unique and important insights into a two-step mechanism by which αBc interacts with misfolded client proteins to prevent their aggregation. Understanding this fundamental mechanism of sHsp action is crucial to understanding how these molecular chaperone function to protect the cell from protein misfolding and their overall role in the cellular proteostasis network.

scholarly journals Deletion of54FLRAPSWF61Residues Decreases the Oligomeric Size and Enhances the Chaperone Function of αB-Crystallin

Biochemistry ◽  
2009 ◽  
Vol 48 (23) ◽  
pp. 5066-5073 ◽  
Author(s):  
Puttur Santhoshkumar ◽  
Raju Murugesan ◽  
K. Krishna Sharma
Keyword(s):  
Chaperone Function ◽  
Αb Crystallin

scholarly journals Phosphorylation of αB-Crystallin Alters Chaperone Function through Loss of Dimeric Substructure

2004 ◽  
Vol 279 (27) ◽  
pp. 28675-28680 ◽  
Author(s):  
J. Andrew Aquilina ◽  
Justin L. P. Benesch ◽  
Lin Lin Ding ◽  
Orna Yaron ◽  
Joseph Horwitz ◽  
...  
Keyword(s):  
Chaperone Function ◽  
Αb Crystallin

scholarly journals Site-Directed Mutations in the C-Terminal Extension of Human αB-Crystallin Affect Chaperone Function and Block Amyloid Fibril Formation

PLoS ONE ◽  
2007 ◽  
Vol 2 (10) ◽  
pp. e1046 ◽  
Author(s):  
Teresa M. Treweek ◽  
Heath Ecroyd ◽  
Danielle M. Williams ◽  
Sarah Meehan ◽  
John A. Carver ◽  
...  
Keyword(s):  
Amyloid Fibril ◽  
Fibril Formation ◽  
Chaperone Function ◽  
Amyloid Fibril Formation ◽  
Αb Crystallin

Tomorrow never knows: Paradoxical effects of a future prime on performance among low socioeconomic status college students

2014 ◽  
Author(s):  
Sarah Dayle Herrmann ◽  
Jessica Bodford ◽  
Robert Adelman ◽  
Oliver Graudejus ◽  
Morris Okun ◽  
...  
Keyword(s):  
College Students ◽  
Socioeconomic Status ◽  
Low Socioeconomic Status ◽  
Low Socioeconomic ◽  
Paradoxical Effects
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