Document Detail

The essential role of the flexible termini in the temperature-responsiveness of the oligomeric state and chaperone-like activity for the polydisperse small heat shock protein IbpB from Escherichia coli.
MedLine Citation:
PMID:  15769476     Owner:  NLM     Status:  MEDLINE    
Small heat shock proteins (sHSPs) represent an abundant and ubiquitous family of molecular chaperones that are believed to prevent irreversible aggregation of other cellular proteins under stress conditions. One of the most prominent features of sHSPs is that they exist as homo-oligomers. Examples of both monodisperse and polydisperse oligomers are found within this family. The small heat shock inclusion-body binding protein B (IbpB) of Escherichia coli, originally discovered as a component of inclusion bodies, exhibits a pronounced polydispersity in its oligomeric state. This research was performed to elucidate the temperature effect on the oligomeric state and chaperone-like activity of the polydisperse IbpB oligomers, as well as the structural basis for such a temperature effect. The data presented here demonstrate that the large oligomers of IbpB progressively dissociate into smaller ones at increasing heat-shock temperatures, accompanied by a notable enhancement of chaperone-like activities. The secondary structure, enriched mainly by beta-strands, is slightly changed with such temperature increases. The dimeric building blocks, which seem to be highly stable, act as the functional unit of IbpB. Limited proteolysis was used to identify the susceptible sites in IbpB that may compose the subunit interfaces, which indicated that the 11 residues at both the N and the C terminus are highly flexible and the removal of each will lead to the formation of dimers, as well as the disappearance of chaperone-like activities. Truncation of 11 residues from either end, using recombinant DNA technology, also led to the formation of dimeric mutant IbpB proteins lacking chaperone-like activities. Taken together, the flexible termini appear to be essential for small heat shock protein IbpB to generate various temperature-responsive oligomers, which exhibit various levels of chaperone-like activities, by interlinking or separating the dimer building blocks.
Wangwang Jiao; Mengding Qian; Pulin Li; Lei Zhao; Zengyi Chang
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of molecular biology     Volume:  347     ISSN:  0022-2836     ISO Abbreviation:  J. Mol. Biol.     Publication Date:  2005 Apr 
Date Detail:
Created Date:  2005-03-16     Completed Date:  2005-04-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985088R     Medline TA:  J Mol Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  871-84     Citation Subset:  IM    
Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, 100084, China.
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MeSH Terms
Circular Dichroism
Escherichia coli / chemistry*,  genetics
Escherichia coli Proteins / chemistry*,  genetics,  metabolism*
Heat-Shock Proteins / chemistry*,  genetics,  metabolism*
Heat-Shock Response* / drug effects
Molecular Chaperones / chemistry*,  genetics,  metabolism*
Protein Denaturation
Protein Structure, Quaternary
Protein Structure, Secondary
Spectroscopy, Fourier Transform Infrared
Urea / pharmacology
Reg. No./Substance:
0/Escherichia coli Proteins; 0/Heat-Shock Proteins; 0/IbpB protein, E coli; 0/Molecular Chaperones; 57-13-6/Urea

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