Enhanced molecular chaperone activity of the small heat-shock protein αB-crystallin following covalent immobilization onto a solid-phase support

Biopolymers ◽  
2011 ◽  
Vol 95 (6) ◽  
pp. 376-389 ◽  
Author(s):  
Megan Garvey ◽  
Stefani S. Griesser ◽  
Hans J. Griesser ◽  
Benjamin Thierry ◽  
Matthew R. Nussio ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Molecular Chaperone ◽  
Solid Phase ◽  
Small Heat Shock Protein ◽  
Covalent Immobilization ◽  
Chaperone Activity ◽  
Αb Crystallin

Interactive Domains for Chaperone Activity in the Small Heat Shock Protein, Human αB Crystallin†

Biochemistry ◽  
2005 ◽  
Vol 44 (45) ◽  
pp. 14854-14869 ◽  
Author(s):  
Joy G. Ghosh ◽  
Marcus R. Estrada ◽  
John I. Clark
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Small Heat Shock Protein ◽  
Chaperone Activity ◽  
Αb Crystallin

scholarly journals Acid-denatured small heat shock protein HdeA from Escherichia coli forms reversible fibrils with an atypical secondary structure

2018 ◽  
Vol 294 (5) ◽  
pp. 1590-1601 ◽  
Author(s):  
Shiori Miyawaki ◽  
Yumi Uemura ◽  
Kunihiro Hongo ◽  
Yasushi Kawata ◽  
Tomohiro Mizobata
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Secondary Structure ◽  
Heat Shock Protein ◽  
Molecular Chaperone ◽  
Protein Function ◽  
Amyloid Fibrils ◽  
Small Heat Shock Protein ◽  
Chaperone Activity

The periplasmic small heat shock protein HdeA from Escherichia coli is inactive under normal growth conditions (at pH 7) and activated only when E. coli cells are subjected to a sudden decrease in pH, converting HdeA into an acid-denatured active state. Here, using in vitro fibrillation assays, transmission EM, atomic-force microscopy, and CD analyses, we found that when HdeA is active as a molecular chaperone, it is also capable of forming inactive aggregates that, at first glance, resemble amyloid fibrils. We noted that the molecular chaperone activity of HdeA takes precedence over fibrillogenesis under acidic conditions, as the presence of denatured substrate protein was sufficient to suppress HdeA fibril formation. Further experiments suggested that the secondary structure of HdeA fibrils deviates somewhat from typical amyloid fibrils and contains α-helices. Strikingly, HdeA fibrils that formed at pH 2 were immediately resolubilized by a simple shift to pH 7 and from there could regain molecular chaperone activity upon a return to pH 1. HdeA, therefore, provides an unusual example of a “reversible” form of protein fibrillation with an atypical secondary structure composition. The competition between active assistance of denatured polypeptides (its “molecular chaperone” activity) and the formation of inactive fibrillary deposits (its “fibrillogenic” activity) provides a unique opportunity to probe the relationship among protein function, structure, and aggregation in detail.

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