Chemical chaperones regulate molecular chaperones in vitro and in cells under combined salt and heat stresses.

Details

Serval ID
serval:BIB_FC20A2F828E5
Type
Article: article from journal or magazin.
Collection
Publications
Title
Chemical chaperones regulate molecular chaperones in vitro and in cells under combined salt and heat stresses.
Journal
Journal of Biological Chemistry
Author(s)
Diamant S., Eliahu N., Rosenthal D., Goloubinoff P.
ISSN
0021-9258 (Print)
ISSN-L
0021-9258
Publication state
Published
Issued date
2001
Peer-reviewed
Oui
Volume
276
Number
43
Pages
39586-39591
Language
english
Abstract
Salt and heat stresses, which are often combined in nature, induce complementing defense mechanisms. Organisms adapt to high external salinity by accumulating small organic compounds known as osmolytes, which equilibrate cellular osmotic pressure. Osmolytes can also act as "chemical chaperones" by increasing the stability of native proteins and assisting refolding of unfolded polypeptides. Adaptation to heat stress depends on the expression of heat-shock proteins, many of which are molecular chaperones, that prevent protein aggregation, disassemble protein aggregates, and assist protein refolding. We show here that Escherichia coli cells preadapted to high salinity contain increased levels of glycine betaine that prevent protein aggregation under thermal stress. After heat shock, the aggregated proteins, which escaped protection, were disaggregated in salt-adapted cells as efficiently as in low salt. Here we address the effects of four common osmolytes on chaperone activity in vitro. Systematic dose responses of glycine betaine, glycerol, proline, and trehalose revealed a regulatory effect on the folding activities of individual and combinations of chaperones GroEL, DnaK, and ClpB. With the exception of trehalose, low physiological concentrations of proline, glycerol, and especially glycine betaine activated the molecular chaperones, likely by assisting local folding in chaperone-bound polypeptides and stabilizing the native end product of the reaction. High osmolyte concentrations, especially trehalose, strongly inhibited DnaK-dependent chaperone networks, such as DnaK+GroEL and DnaK+ClpB, likely because high viscosity affects dynamic interactions between chaperones and folding substrates and stabilizes protein aggregates. Thus, during combined salt and heat stresses, cells can specifically control protein stability and chaperone-mediated disaggregation and refolding by modulating the intracellular levels of different osmolytes.
Keywords
Adaptation, Biological/physiology, Bacterial Proteins/metabolism, Betaine/pharmacology, Chaperonin 60/metabolism, Escherichia coli/physiology, Escherichia coli Proteins, Glycerol/pharmacology, HSP40 Heat-Shock Proteins, HSP70 Heat-Shock Proteins/metabolism, Heat-Shock Proteins/metabolism, Hot Temperature, Malate Dehydrogenase/metabolism, Molecular Chaperones/metabolism, Osmotic Pressure, Proline/pharmacology, Protein Denaturation/drug effects, Protein Folding, Salts, Trehalose/pharmacology, Urea/pharmacology, Viscosity
Pubmed
Web of science
Open Access
Yes
Create date
24/01/2008 21:02
Last modification date
20/08/2019 17:27
Usage data