Details
| Original language | English |
|---|---|
| Pages (from-to) | 5364-5371 |
| Number of pages | 8 |
| Journal | Journal of Bacteriology |
| Volume | 176 |
| Issue number | 17 |
| Publication status | Published - Sept 1994 |
| Externally published | Yes |
Abstract
Exogenously provided glycine betaine functions as an efficient osmoprotectant for Bacillus subtilis in high-osmolarity environments. This gram-positive soil organism is not able to increase the intracellular level of glycine betaine through de novo synthesis in defined medium (A. M. Whatmore, J. A. Chudek, and R. H. Reed, J. Gen. Microbiol. 136:2527-2535, 1990). We found, however, that B. subtilis can synthesize glycine betaine when its biosynthetic precursor, choline, is present in the growth medium. Uptake studies with radiolabelled [methyl-14C]choline demonstrated that choline transport is osmotically controlled and is mediated by a high- affinity uptake system. Choline transport of cells grown in low- and high- osmolarity media showed Michaelis-Menten kinetics with K(m) values of 3 and 5 μM and maximum rates of transport (V(max)) of 10 and 36 nmol min-1 mg of protein-1, respectively. The choline transporter exhibited considerable substrate specificity, and the results of competition experiments suggest that the fully methylated quaternary ammonium group is a key feature for substrate recognition. Thin-layer chromatography revealed that the radioactivity from exogenously provided [methyl-14C]choline accumulated intracellularly as [methyl-14C]glycine betaine, demonstrating that B. subtilis possesses enzymes for the oxidative conversion of choline into glycine betaine. Exogenously provided choline significantly increased the growth rate of B. subtilis in high-osmolarity media and permitted its proliferation under conditions that are otherwise strongly inhibitory for its growth. Choline and glycine betaine were not used as sole sources of carbon or nitrogen, consistent with their functional role in the process of adaptation of B. subtilis to high-osmolarity stress.
ASJC Scopus subject areas
- Immunology and Microbiology(all)
- Microbiology
- Biochemistry, Genetics and Molecular Biology(all)
- Molecular Biology
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In: Journal of Bacteriology, Vol. 176, No. 17, 09.1994, p. 5364-5371.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Osmoregulation in Bacillus subtilis: synthesis of the osmoprotectant glycine betaine from exogenously provided choline
AU - Boch, Jens
AU - Kempf, Bettina
AU - Bremer, Erhard
N1 - Copyright: Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1994/9
Y1 - 1994/9
N2 - Exogenously provided glycine betaine functions as an efficient osmoprotectant for Bacillus subtilis in high-osmolarity environments. This gram-positive soil organism is not able to increase the intracellular level of glycine betaine through de novo synthesis in defined medium (A. M. Whatmore, J. A. Chudek, and R. H. Reed, J. Gen. Microbiol. 136:2527-2535, 1990). We found, however, that B. subtilis can synthesize glycine betaine when its biosynthetic precursor, choline, is present in the growth medium. Uptake studies with radiolabelled [methyl-14C]choline demonstrated that choline transport is osmotically controlled and is mediated by a high- affinity uptake system. Choline transport of cells grown in low- and high- osmolarity media showed Michaelis-Menten kinetics with K(m) values of 3 and 5 μM and maximum rates of transport (V(max)) of 10 and 36 nmol min-1 mg of protein-1, respectively. The choline transporter exhibited considerable substrate specificity, and the results of competition experiments suggest that the fully methylated quaternary ammonium group is a key feature for substrate recognition. Thin-layer chromatography revealed that the radioactivity from exogenously provided [methyl-14C]choline accumulated intracellularly as [methyl-14C]glycine betaine, demonstrating that B. subtilis possesses enzymes for the oxidative conversion of choline into glycine betaine. Exogenously provided choline significantly increased the growth rate of B. subtilis in high-osmolarity media and permitted its proliferation under conditions that are otherwise strongly inhibitory for its growth. Choline and glycine betaine were not used as sole sources of carbon or nitrogen, consistent with their functional role in the process of adaptation of B. subtilis to high-osmolarity stress.
AB - Exogenously provided glycine betaine functions as an efficient osmoprotectant for Bacillus subtilis in high-osmolarity environments. This gram-positive soil organism is not able to increase the intracellular level of glycine betaine through de novo synthesis in defined medium (A. M. Whatmore, J. A. Chudek, and R. H. Reed, J. Gen. Microbiol. 136:2527-2535, 1990). We found, however, that B. subtilis can synthesize glycine betaine when its biosynthetic precursor, choline, is present in the growth medium. Uptake studies with radiolabelled [methyl-14C]choline demonstrated that choline transport is osmotically controlled and is mediated by a high- affinity uptake system. Choline transport of cells grown in low- and high- osmolarity media showed Michaelis-Menten kinetics with K(m) values of 3 and 5 μM and maximum rates of transport (V(max)) of 10 and 36 nmol min-1 mg of protein-1, respectively. The choline transporter exhibited considerable substrate specificity, and the results of competition experiments suggest that the fully methylated quaternary ammonium group is a key feature for substrate recognition. Thin-layer chromatography revealed that the radioactivity from exogenously provided [methyl-14C]choline accumulated intracellularly as [methyl-14C]glycine betaine, demonstrating that B. subtilis possesses enzymes for the oxidative conversion of choline into glycine betaine. Exogenously provided choline significantly increased the growth rate of B. subtilis in high-osmolarity media and permitted its proliferation under conditions that are otherwise strongly inhibitory for its growth. Choline and glycine betaine were not used as sole sources of carbon or nitrogen, consistent with their functional role in the process of adaptation of B. subtilis to high-osmolarity stress.
UR - http://www.scopus.com/inward/record.url?scp=0028106108&partnerID=8YFLogxK
U2 - 10.1128/jb.176.17.5364-5371.1994
DO - 10.1128/jb.176.17.5364-5371.1994
M3 - Article
C2 - 8071213
AN - SCOPUS:0028106108
VL - 176
SP - 5364
EP - 5371
JO - Journal of Bacteriology
JF - Journal of Bacteriology
SN - 0021-9193
IS - 17
ER -