scholarly journals Synthesis of Glycine Betaine from Exogenous Choline in the Moderately Halophilic Bacterium Halomonas elongata

1998 ◽  
Vol 64 (10) ◽  
pp. 4095-4097 ◽  
Author(s):  
David Cánovas ◽  
Carmen Vargas ◽  
Laszlo N. Csonka ◽  
Antonio Ventosa ◽  
Joaquín J. Nieto
Keyword(s):  
Growth Medium ◽  
Glycine Betaine ◽  
Halophilic Bacterium ◽  
Intracellular Accumulation ◽  
Moderate Halophile ◽  
Moderately Halophilic ◽  
Moderately Halophilic Bacterium ◽  
Halomonas Elongata ◽  
Nacl Concentration

ABSTRACT The role of choline in osmoprotection in the moderate halophileHalomonas elongata has been examined. Transport and conversion of choline to betaine began immediately after addition of choline to the growth medium. Intracellular accumulation of betaine synthesized from choline was salt dependent up to 2.5 M NaCl. Oxidation of choline was enhanced at 2.0 M NaCl in the presence or absence of externally provided betaine. This indicates that the NaCl concentration in the growth medium has major effects on the choline-betaine pathway of H. elongata.

scholarly journals Chloride, a New Environmental Signal Molecule Involved in Gene Regulation in a Moderately Halophilic Bacterium, Halobacillus halophilus

2002 ◽  
Vol 184 (22) ◽  
pp. 6207-6215 ◽  
Author(s):  
Markus Roeβler ◽  
Volker Müller
Keyword(s):  
Halophilic Bacterium ◽  
Dependent Manner ◽  
Gene Encoding ◽  
Signal Molecule ◽  
Two Dimensional Gel Electrophoresis ◽  
Moderate Halophile ◽  
General Role ◽  
Moderately Halophilic ◽  
Environmental Signal ◽  
Moderately Halophilic Bacterium

ABSTRACT The gram-positive, aerobic, moderately halophilic bacterium Halobacillus halophilus is challenged in its environment by frequently changing salt (NaCl) concentrations. Recently, H. halophilus was shown to be the first prokaryote that is dependent on Cl− for growth. In a search for the biological function of Cl− in this prokaryote, we identified different Cl−-dependent processes, which suggests a more general role for Cl− in the metabolism of H. halophilus. To analyze the effect of Cl− in more detail, we concentrated on one model system, the Cl−-dependent production of flagella, and aimed to identify the molecular basis for the Cl− dependence of flagellum production. Here, we report that synthesis of the major subunit of the flagellum, FliC, is dependent on the Cl− concentration of the medium, as determined by Western blot analyses. The gene encoding FliC was cloned and sequenced, and Northern blot as well as reverse transcriptase PCR analyses revealed that expression of fliC is Cl− dependent. FliC is the first protein of known function demonstrated to be synthesized in a Cl−-dependent manner in a prokaryote. Two-dimensional gel electrophoresis of cells grown under different conditions revealed five more Cl−-induced proteins; these were identified by N-terminal sequencing and database searches to be orthologs of proteins involved in stress response in Bacillus subtilis. The data indicate that Cl− is an important environmental signal in this moderate halophile and regulates protein synthesis and gene expression. Furthermore, the data may suggest that Cl− plays a role in the signal transduction involved in salt perception by this bacterium.

The intracellular Na+ and K+ composition of the moderately halophilic bacterium, Paracoccus halodenitrificans

1980 ◽  
Vol 26 (4) ◽  
pp. 496-502 ◽  
Author(s):  
M. Sadler ◽  
M. McAninch ◽  
R. Alico ◽  
L. I. Hochstein
Keyword(s):  
Stationary Phase ◽  
Growth Medium ◽  
Nadh Oxidase ◽  
Halophilic Bacterium ◽  
Oxidase System ◽  
Final Value ◽  
Moderately Halophilic Bacterium ◽  
Nacl Concentration ◽  
Atp Pool ◽  
Membrane Bound

The intracellular concentrations of Na+ and K+ in exponentially growing Paracoccus halodenitrificans were independent of the NaCl concentration of the growth medium. The observed values were approximately 100 and 300 mM for Na+ and K+, respectively. In stationary phase cells, the ultimate values for Na+ depended on the NaCl concentration of the growth medium. With cells grown in the presence of 1 M NaCl, the value was about 500 mM; for cells grown in the presence of 3 M NaCl, the value was about 1.1 M. The K+ concentration in stationary phase cells was unaffected by the NaCl concentration in the growth medium. The final value was about 100 mM. Associated with these changes were changes in the ATP pool and decreases in the activities of the NADH oxidase system and the membrane-bound ATPase. It is proposed that the decrease in the activities of these enzymes may account for the ion flows observed in stationary phase cells.

Protein turnover in a moderately halophilic bacterium

1980 ◽  
Vol 26 (2) ◽  
pp. 196-203 ◽  
Author(s):  
A. R. Hipkiss ◽  
D. W. Armstrong ◽  
D. J. Kushner
Keyword(s):  
Protein Turnover ◽  
Critical Factor ◽  
Optimal Growth ◽  
Halophilic Bacterium ◽  
High Rate ◽  
Breakdown Rate ◽  
Intact Cells ◽  
Moderately Halophilic ◽  
Moderately Halophilic Bacterium ◽  
Nacl Concentration

Protein turnover was investigated in exponentially growing Vibrio costicola, a moderately halophilic bacterium that can grow in the NaCl concentration range 0.5–3.5 M (with optimal growth at about 1.0 M). In 1.0 or 1.5 M NaCl the breakdown rate of pulse-labelled proteins was about 5%/h whereas in 0.5 M NaCl breakdown was about 9%/h. These results are in contrast to those reported and observed in Escherichia coli which has a turnover rate of 1–2%/h in exponential growth. Growing E. coli in the highest possible NaCl concentration (1.0 M) did not significantly increase protein turnover. Shifting V. costicola from a higher to a lower NaCl concentration increased the rate of turnover of pulse-labelled proteins, whereas shifting it from a lower to a higher NaCl concentration decreased the rate of turnover. The critical factor in these experiments was not the NaCl concentration at which proteins were labelled but that at which the cells were subsequently incubated. The level of breakdown of long-labelled proteins was low (about 2%/h) and was not affected by shifts in NaCl concentration. Breakdown of pulse-labelled protein was inhibited by cyanide and tetracycline but not by iodoacetate, azide. or chloramphenicol. Treatment with streptomycin increased the rate of turnover. Turnover in cell-free systems was lower than in intact cells and was not inhibited by cyanide or tetracycline. It is suggested that the high rate of turnover, even at optimal NaCl concentrations, may reflect errors in protein synthesis, and that the effect of lower NaCl concentrations may be to alter "native" conformation and thus to increase the susceptibility of some of the properly made proteins to proteolysis.

Intracellular concentrations of Na+, K+, and Cl− of a moderately halophilic bacterium

1973 ◽  
Vol 19 (10) ◽  
pp. 1181-1186 ◽  
Author(s):  
Masamiki Masui ◽  
Sumi Wada
Keyword(s):  
Cell Envelope ◽  
Halophilic Bacterium ◽  
Defined Medium ◽  
Moderately Halophilic ◽  
Whole Cells ◽  
Moderately Halophilic Bacterium ◽  
Intracellular Concentrations ◽  
Isolated Cell ◽  
Very High

The intracellular concentrations of Na+, K+, and Cl− of an unidentified moderately halophilic bacterium were determined. When the cells were grown at a late linear growth phase in a chemically defined medium containing 1, 2, or 3 M NaCl and 5.5 mM K+, the intracellular Na+ concentration (0.90–1.15 M) was independent of the Na+ in the medium. The K+ and Cl− concentrations were roughly on the same levels, respectively (0.67–0.89 M K+; 0.70–0.98 M Cl−). The Na+ and K+ per gram protein of the whole cells were 3.85 mmol and 2.96 mmol, respectively. When the cell envelope was incubated in a 2 M NaCl solution containing 5.5 mM K+ and 0.1 mM Mg2+, the Na+ concentration in the cell envelope was very high (6.49 mmol per gram protein) and K+ was concentrated up to about 41 times of the external K+ (0.36 mmol per gram protein). The high Na+ content of the isolated cell envelope may serve as one of the keys to elucidating a role of Na+ for the maintenance of the cell rigidity in this bacterium.

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