Document Detail

Body shaping under water stress: osmosensing and osmoregulation of solute transport in bacteria.
MedLine Citation:
PMID:  12007171     Owner:  NLM     Status:  MEDLINE    
Fluctuation of external osmolarity is one of the most common types of environmental stress factors for all kind of cells, both of prokaryotic and of eukaryotic origin. Cells try to keep their volume and/or turgor pressure constant; consequently, both a decrease (hypoosmotic stress) and an increase (hyperosmotic stress) of the solute concentration (correctly: increase or decrease in water activity) in the surrounding area, respectively, are challenges for cellular metabolism and survival. A common example from the prokaryotic world is the fate of a soil bacterium that, after a sunny day has dried out the soil (hyperosmotic stress), is suddenly exposed to a drop of distilled water from a rain cloud (hypoosmotic stress). The immediate and inevitable passive response to the sudden osmotic shift in the surroundings is fast water efflux out of the cell in the former situation and water influx in the latter. In the worst case, these responses may lead to either loss of cell turgor and plasmolysis or to cell burst. In order to overcome such drastic consequences cells have developed effective mechanisms, namely osmoadaptation, to cope with the two different types of osmotic stress. For a graded reaction to osmotic shifts, cells must be able (1) to sense stimuli related to osmotic stress, (2) to transduce corresponding signals to those systems that properly respond (3) by activating transport or enzymatic functions or (4) by changing gene expression profiles. In this review, membrane proteins involved in the cell's active response to osmotic stress are described. Molecular details of structure, function, and regulation of mechanosensitive efflux channels from various organisms, as well as of osmoregulated uptake systems are discussed.
Susanne Morbach; Reinhard Krämer
Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  Chembiochem : a European journal of chemical biology     Volume:  3     ISSN:  1439-4227     ISO Abbreviation:  Chembiochem     Publication Date:  2002 May 
Date Detail:
Created Date:  2002-05-23     Completed Date:  2002-11-04     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  100937360     Medline TA:  Chembiochem     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  384-97     Citation Subset:  IM    
Institut für Biochemie der Universität zu Köln, Zülpicher Strasse 47, 50674 Köln, Germany.
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MeSH Terms
Adaptation, Physiological
Bacterial Physiological Phenomena*
Bacterial Proteins / metabolism
Biological Transport
Cell Size
Osmolar Concentration
Signal Transduction / physiology*
Water / metabolism*
Water-Electrolyte Balance / physiology
Reg. No./Substance:
0/Bacterial Proteins; 7732-18-5/Water

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

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