The effects of osmotic upshock on the intracellular solute pools of Bacillus subtilis

Whatmore, Adrian M.; Chudek, J. A.; Reed, Robert H.

doi:10.1099/00221287-136-12-2527

Cited by 260 publications

(352 citation statements)

References 36 publications

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“…1) (Belitsky et al, 2001). Since the biosynthesis of amino acids is energetically expensive (Akashi & Gojobori, 2002), B. subtilis has to carefully adjust its proline biosynthetic capacities to produce the amounts needed for these very different physiological tasks (Bremer, 2002; Whatmore et al, 1990). Our data show that the transcription of the anabolic proBA operon and that of the proI gene is regulated through a proline-responsive T-box regulatory system.…”

Section: Discussionmentioning

confidence: 79%

“…The cellular pools required for proline as a building block for protein synthesis and as an osmostress protectant are very different. Osmotically non-stressed B. subtilis cells have a proline pool of about 16 mM, and those subjected to a modest osmotic up-shock with 0.4 M NaCl amass proline to a concentration of about 0.5-0.7 M (Whatmore et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

“…Proline also serves as an important osmostress protectant (Bremer, 2002). For this task, proline can either be taken up by B. subtilis from the environment via the osmotically inducible OpuE transporter (Spiegelhalter & Bremer, 1998;von Blohn et al, 1997) or be produced in very large quantities from the precursor glutamate (Belitsky et al, 2001;Whatmore et al, 1990). Proline belongs to a selected group of organic osmolytes, the compatible solutes, which are amassed by many micro-organisms to adapt to high-osmolarity growth conditions (Kempf & Bremer, 1998).…”

Section: Introductionmentioning

confidence: 99%

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T-box-mediated control of the anabolic proline biosynthetic genes of Bacillus subtilis

et al. 2011

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Bacillus subtilis possesses interlinked routes for the synthesis of proline. The ProJ-ProA-ProH route is responsible for the production of proline as an osmoprotectant, and the ProB-ProA-ProI route provides proline for protein synthesis. We show here that the transcription of the anabolic proBA and proI genes is controlled in response to proline limitation via a T-box-mediated termination/antitermination regulatory mechanism, a tRNA-responsive riboswitch. Primer extension analysis revealed mRNA leader transcripts of 270 and 269 nt for the proBA and proI genes, respectively, both of which are synthesized from SigA-type promoters. These leader transcripts are predicted to fold into two mutually exclusive secondary mRNA structures, forming either a terminator or an antiterminator configuration. Northern blot analysis allowed the detection of both the leader and the full-length proBA and proI transcripts. Assessment of the level of the proBA transcripts revealed that the amount of the full-length mRNA species strongly increased in proline-starved cultures. Genetic studies with a proB-treA operon fusion reporter strain demonstrated that proBA transcription is sensitively tied to proline availability and is derepressed as soon as cellular starvation for proline sets in. Both the proBA and the proI leader sequences contain a CCU proline-specific specifier codon prone to interact with the corresponding uncharged proline-specific tRNA. By replacing the CCU proline specifier codon in the proBA T-box leader with UUC, a codon recognized by a Phe-specific tRNA, we were able to synthetically re-engineer the proline-specific control of proBA transcription to a control that was responsive to starvation for phenylalanine.

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Section: Discussionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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T-box-mediated control of the anabolic proline biosynthetic genes of Bacillus subtilis

et al. 2011

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“…Significant quantities of glycine betaine are intracellularly accumulated by B. subtilis from exogenous sources or through synthesis from choline even in media of low or moderate osmolarity (4,54). This phenomenon is probably connected with the maintenance of the very high turgor found in B. subtilis (55).…”

Section: Vol 178 1996 Glycine Betaine Synthesis In B Subtilis 5127mentioning

confidence: 99%

“…Exposure of Bacillus subtilis to a hypersaline environment incites an integrated physiological adaptation reaction that is aimed at restoring the disturbed cellular water balance, maintaining optimal turgor, and protecting cell components from the detrimental effects of high ionic strength. It consists of an initial rapid influx of K ϩ ions and the onset of increased proline biosynthesis (54,55). In addition, the expression of a general stress regulon that is also responsive to other growth-limiting conditions and to stationary-phase signals is induced (20).…”

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confidence: 99%

Synthesis of the osmoprotectant glycine betaine in Bacillus subtilis: characterization of the gbsAB genes

et al. 1996

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Synthesis of the osmoprotectant glycine betaine from the exogenously provided precursor choline or glycine betaine aldehyde confers considerable osmotic stress tolerance to Bacillus subtilis in high-osmolarity media. Using an Escherichia coli mutant (betBA) defective in the glycine betaine synthesis enzymes, we cloned by functional complementation the genes that are required for the synthesis of the osmoprotectant glycine betaine in B. subtilis. The DNA sequence of a 4.1-kb segment from the cloned chromosomal B. subtilis DNA was established, and two genes (gbsA and gbsB) whose products were essential for glycine betaine biosynthesis and osmoprotection were identified. The gbsA and gbsB genes are transcribed in the same direction, are separated by a short intergenic region, and are likely to form an operon. The deduced gbsA gene product exhibits strong sequence identity with members of a superfamily of specialized and nonspecialized aldehyde dehydrogenases. This superfamily comprises glycine betaine aldehyde dehydrogenases from bacteria and plants with known involvement in the cellular adaptation to high-osmolarity stress and drought. The deduced gbsB gene product shows significant similarity to the family of type III alcohol dehydrogenases. B. subtilis mutants with defects in the chromosomal gbsAB genes were constructed by marker replacement, and the growth properties of these mutant strains in high-osmolarity medium were analyzed. Deletion of the gbsAB genes destroyed the cholineglycine betaine synthesis pathway and abolished the ability of B. subtilis to deal effectively with high-osmolarity stress in choline-or glycine betaine aldehyde-containing medium. Uptake of radiolabelled choline was unaltered in the gbsAB mutant strain. The continued intracellular accumulation of choline or glycine betaine aldehyde in a strain lacking the glycine betaine-biosynthetic enzymes strongly interfered with the growth of B. subtilis, even in medium of moderate osmolarity. A single transcription initiation site for gbsAB was detected by high-resolution primer extension analysis. gbsAB transcription was initiated from a promoter with close homology to A -dependent promoters and was stimulated by the presence of choline in the growth medium.

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Body Shaping under Water Stress: Osmosensing and Osmoregulation of Solute Transport in Bacteria

2002

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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.

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The effects of osmotic upshock on the intracellular solute pools of Bacillus subtilis

Cited by 260 publications

References 36 publications

T-box-mediated control of the anabolic proline biosynthetic genes of Bacillus subtilis

T-box-mediated control of the anabolic proline biosynthetic genes of Bacillus subtilis

Synthesis of the osmoprotectant glycine betaine in Bacillus subtilis: characterization of the gbsAB genes

Body Shaping under Water Stress: Osmosensing and Osmoregulation of Solute Transport in Bacteria

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