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Novel insights into the role of potassium for osmoregulation in Halomonas elongata.
- Source :
-
Extremophiles : life under extreme conditions [Extremophiles] 2002 Dec; Vol. 6 (6), pp. 453-62. Date of Electronic Publication: 2002 Jul 13. - Publication Year :
- 2002
-
Abstract
- 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.
- Subjects :
- Adaptation, Physiological
Amino Acids, Diamino biosynthesis
Halomonas drug effects
Halomonas growth & development
Halomonas metabolism
Ion Transport
Osmotic Pressure
Oxygen Consumption
Potassium pharmacology
Saline Solution, Hypertonic pharmacology
Halomonas physiology
Potassium physiology
Water-Electrolyte Balance physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1431-0651
- Volume :
- 6
- Issue :
- 6
- Database :
- MEDLINE
- Journal :
- Extremophiles : life under extreme conditions
- Publication Type :
- Academic Journal
- Accession number :
- 12486453
- Full Text :
- https://doi.org/10.1007/s00792-002-0277-4