Document Detail


Transient accumulation of potassium glutamate and its replacement by trehalose during adaptation of growing cells of Escherichia coli K-12 to elevated sodium chloride concentrations.
MedLine Citation:
PMID:  3060036     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The sequence of events following the addition of 0.5 M NaCl to cells of Escherichia coli growing in a minimal mineral medium was investigated. Immediately after upshock the cells took up a large amount of K+ and synthesized approximately half the equivalent amount of glutamate concomitantly. After 30 min the cells started to synthesize trehalose, and after 2 h they had replaced most of their initial osmoprotectants by the carbohydrate. Cell trehalose was rapidly replaced by proline, taken up from the medium when added to the osmoadapting cells. The initial rate of this proline uptake was extremely rapid, and with rates observed of up to 0.6 mmol x min-1 x g-1 of cell protein it was approximately ten times faster than that reported in the literature for non-growing cells. These results indicate that for osmoadaptation of growing cells of E. coli the uptake of proline has priority over the synthesis of trehalose, which in its turn is preferred above K+ and glutamate as osmoprotectants. We observed that two mutants with unknown lesions, but which are known to be impaired in osmoadaptation, were inhibited in replacing K+ and glutamate by trehalose, indicating that this is the basis for their defect in osmoadaptation. Further experiments revealed that neither internal pH nor the membrane potential nor the transmembrane protonmotive force are likely to be involved in osmoadaptation in E. coli. However, during osmoadaptation a high internal potassium concentration appeared to stimulate the derepression of proline-uptake systems (mainly system ProP).
Authors:
U Dinnbier; E Limpinsel; R Schmid; E P Bakker
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Archives of microbiology     Volume:  150     ISSN:  0302-8933     ISO Abbreviation:  Arch. Microbiol.     Publication Date:  1988  
Date Detail:
Created Date:  1989-01-17     Completed Date:  1989-01-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0410427     Medline TA:  Arch Microbiol     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  348-57     Citation Subset:  IM    
Affiliation:
Fachgebiet Mikrobiologie, Universität Osnabrück, Federal Republic of Germany.
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MeSH Terms
Descriptor/Qualifier:
Biological Transport, Active
Disaccharides / biosynthesis*
Escherichia coli / genetics,  metabolism*
Glutamates / biosynthesis*
Hydrogen-Ion Concentration
Membrane Potentials
Mutation
Osmolar Concentration
Osmotic Pressure
Potassium / metabolism*
Proline / metabolism
Trehalose / biosynthesis*
Chemical
Reg. No./Substance:
0/Disaccharides; 0/Glutamates; 147-85-3/Proline; 7440-09-7/Potassium; 99-20-7/Trehalose

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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