Document Detail

Novel insights into the role of potassium for osmoregulation in Halomonas elongata.
MedLine Citation:
PMID:  12486453     Owner:  NLM     Status:  MEDLINE    
The role of K(+) in osmoregulation of the halophilic bacterium Halomonas elongata was investigated. At lower salinities (0.51 M NaCl), K(+) was the predominant cytoplasmic solute (1.25 micro mol mg protein(-1)). At higher salinities (1.03 M NaCl) ectoine became the main cytoplasmic solute (1.57 micro mol mg protein(-1)), while the K(+) content remained unchanged. In response to osmotic upshock, cells of H. elongata simultaneously accumulated ectoine and K(+) glutamate. The ectoine and K(+) glutamate levels in osmotically stressed cells exceeded the level of cells adapted to high salinities. The increase in K(+) glutamate was long lasting (>120 min) and not transient, as described for non-halophiles. Regulation of the synthesis of ectoine and glutamate was proven to occur mainly at the level of enzyme activity. Limitation of K(+) inhibited the growth of salt-adapted H. elongata cells, especially at high salinities, and caused a decrease of the intracellular organic solute content, inhibition of respiration, and an abolition of the cell's ability to respond to osmotic stress. The saturation constant K(S) for K(+) was estimated to be 105 micro M at a salinity of 0.51 M NaCl, indicating that an uptake system of medium affinity is responsible for K(+) accumulation in H. elongata.
Annette Kraegeloh; Hans Jörg Kunte
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2002-07-13
Journal Detail:
Title:  Extremophiles : life under extreme conditions     Volume:  6     ISSN:  1431-0651     ISO Abbreviation:  Extremophiles     Publication Date:  2002 Dec 
Date Detail:
Created Date:  2002-12-17     Completed Date:  2003-06-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9706854     Medline TA:  Extremophiles     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  453-62     Citation Subset:  IM; S    
Institut für Mikrobiologie und Biotechnologie, Rheinische Friedrich-Wilhelms Universität, Meckenheimer Allee 168, 53115 Bonn, Germany.
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MeSH Terms
Adaptation, Physiological
Amino Acids, Diamino / biosynthesis
Halomonas / drug effects,  growth & development,  metabolism,  physiology*
Ion Transport
Osmotic Pressure
Oxygen Consumption
Potassium / pharmacology,  physiology*
Saline Solution, Hypertonic / pharmacology
Water-Electrolyte Balance / physiology*
Reg. No./Substance:
0/Amino Acids, Diamino; 0/Saline Solution, Hypertonic; 7440-09-7/Potassium; 96702-03-3/ectoine
Erratum In:
Extremophiles. 2003 Jun;7(3): 259

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

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