Osmoregulation in Bacteria: Compatible Solute Accumulation and Osmosensing

2006 ◽  
Vol 3 (2) ◽  
pp. 94 ◽  
Author(s):  
Hans Jörg Kunte
Keyword(s):  
Osmotic Stress ◽  
Surrounding Medium ◽  
Compatible Solutes ◽  
Compatible Solute ◽  
Water Soluble ◽  
Fine Tuning ◽  
Transport Systems ◽  
Organic Osmolytes ◽  
Organic Osmolyte ◽  
Solute Accumulation

Environmental Context.Bacteria and Archaea have developed two basic mechanisms to cope with osmotic stress. The ‘salt-in-cytoplasm mechanism’ involves adjusting the salt concentration in the cytoplasm according to the environmental osmolarity and the ‘organic-osmolyte mechanism’ involves accumulating uncharged, highly water-soluble organic compounds in order to maintain an osmotic equilibrium with the surrounding medium. This highlight gives an overview of the osmoadaptation of prokaryotes employing the organic-osmolyte strategy and introduces a model explaining the fine-tuning of osmoregulatory osmolyte synthesis. Abstract.Bacteria and Archaea have developed two basic mechanisms to cope with osmotic stress, the salt-in-cytoplasm mechanism, and the organic-osmolyte mechanism. Organic osmolytes or so-called compatible solutes can be accumulated in molar concentration in the cytoplasm and allow for the adaptation of bacterial cells to varying salt concentrations. The biosynthetic pathways of compatible solutes and different compatible solute transport systems are described. A model for osmoregulatory compatible solute accumulation is introduced.

Guardians in a stressful world: the Opu family of compatible solute transporters from Bacillus subtilis

2017 ◽  
Vol 398 (2) ◽  
pp. 193-214 ◽  
Author(s):  
Tamara Hoffmann ◽  
Erhard Bremer
Keyword(s):  
Bacillus Subtilis ◽  
Osmotic Stress ◽  
Cytoplasmic Membrane ◽  
Compatible Solutes ◽  
Transport Systems ◽  
Osmotic Gradient ◽  
Organic Osmolytes ◽  
Water Fluxes ◽  
Water Efflux ◽  
Response Systems

AbstractThe development of a semi-permeable cytoplasmic membrane was a key event in the evolution of microbial proto-cells. As a result, changes in the external osmolarity will inevitably trigger water fluxes along the osmotic gradient. The ensuing osmotic stress has consequences for the magnitude of turgor and will negatively impact cell growth and integrity. No microorganism can actively pump water across the cytoplasmic membrane; hence, microorganisms have to actively adjust the osmotic potential of their cytoplasm to scale and direct water fluxes in order to prevent dehydration or rupture. They will accumulate ions and physiologically compliant organic osmolytes, the compatible solutes, when they face hyperosmotic conditions to retain cell water, and they rapidly expel these compounds through the transient opening of mechanosensitive channels to curb water efflux when exposed to hypo-osmotic circumstances. Here, we provide an overview on the salient features of the osmostress response systems of the ubiquitously distributed bacteriumBacillus subtiliswith a special emphasis on the transport systems and channels mediating regulation of cellular hydration and turgor under fluctuating osmotic conditions. The uptake of osmostress protectants via the Opu family of transporters, systems of central importance for the management of osmotic stress byB. subtilis, will be particularly highlighted.

scholarly journals Role of σB in Regulating the Compatible Solute Uptake Systems of Listeria monocytogenes: Osmotic Induction of opuC Is σB Dependent

2003 ◽  
Vol 69 (4) ◽  
pp. 2015-2022 ◽  
Author(s):  
Katy R. Fraser ◽  
David Sue ◽  
Martin Wiedmann ◽  
Kathryn Boor ◽  
Conor P. O'Byrne
Keyword(s):  
Listeria Monocytogenes ◽  
Solute Transport ◽  
Compatible Solutes ◽  
Strain Analysis ◽  
Compatible Solute ◽  
Transport Systems ◽  
Carnitine Transporter ◽  
Solute Uptake ◽  
Carnitine Transport

ABSTRACT The regulation of the compatible solute transport systems in Listeria monocytogenes by the stress-inducible sigma factor σB was investigated. Using wild-type strain 10403S and an otherwise isogenic strain carrying an in-frame deletion in sigB, we have examined the role of σB in regulating the ability of cells to utilize betaine and carnitine during growth under conditions of hyperosmotic stress. Cells lacking σB were defective for the utilization of carnitine but retained the ability to utilize betaine as an osmoprotectant. When compatible solute transport studies were performed, the initial rates of uptake of both betaine and carnitine were found to be reduced in the sigB mutant; carnitine transport was almost abolished, whereas betaine transport was reduced to approximately 50% of that of the parent strain. Analysis of the cytoplasmic pools of compatible solutes during balanced growth revealed that both carnitine and betaine steady-state pools were reduced in the sigB mutant. Transcriptional reporter fusions to the opuC (which encodes an ABC carnitine transporter) and betL (which encodes an a secondary betaine transporter) operons were generated by using a promoterless copy of the gus gene from Escherichia coli. Measurement of β-glucuronidase activities directed by opuC-gus and betL-gus revealed that transcription of opuC is largely σB dependent, consistent with the existence of a potential σB consensus promoter motif upstream from opuCA. The transcription of betL was found to be sigB independent. Reverse transcriptase PCR experiments confirmed these data and indicated that the transcription of all three known compatible solute uptake systems (opuC, betL, and gbu), as well as a gene that is predicted to encode a compatible solute transporter subunit (lmo1421) is induced in response to elevated osmolarity. The osmotic induction of opuCA and lmo1421 was found to be strongly σB dependent. Together these observations suggest that σB plays a major role in the regulation of carnitine utilization by L. monocytogenes but is not essential for betaine utilization by this pathogen.

Ectoine as a natural component of food: detection in red smear cheeses

2007 ◽  
Vol 74 (4) ◽  
pp. 446-451 ◽  
Author(s):  
Julia Klein ◽  
Thomas Schwarz ◽  
Georg Lentzen
Keyword(s):  
Osmotic Stress ◽  
Halophilic Bacteria ◽  
Compatible Solutes ◽  
Compatible Solute ◽  
Brevibacterium Linens ◽  
Food Detection ◽  
Different Types ◽  
Cheese Production ◽  
Natural Component ◽  
Red Smear Cheese

Ectoine is a compatible solute accumulated in halophilic bacteria in response to high salt concentrations and offers protection from osmotic stress. The occurrence of compatible solutes is widespread among bacteria, yet ectoine has never been detected in foods. The use of an ectoine producing microorganism (Brevibacterium linens) in the surface ripening of red smear cheeses led to the question whether ectoine can be found in cheese. Therefore we examined samples from a variety of cheese manufacturers and different types of red smear cheeses for the presence of ectoine using HPLC and HPLC/MS analysis. Ectoine solely appears in the rind and was detected up to 178 mg/200 g red smear cheese, depending on several factors like ripening status and conditions throughout the cheese production process (e.g. salt concentrations of used brine baths).

The Compability with Enzyme Activity of Unusual Organic Osmolytes from Mangrove Red Algae

1996 ◽  
Vol 23 (5) ◽  
pp. 577 ◽  
Author(s):  
U Karsten ◽  
KD Barrow ◽  
O Nixdorf ◽  
RJ King
Keyword(s):  
Red Algae ◽  
Citric Acid Cycle ◽  
Compatible Solutes ◽  
Pentose Phosphate ◽  
Organic Osmolytes ◽  
Maximum Solubility ◽  
Organic Osmolyte ◽  
Negative Effect ◽  
Glucose 6 Phosphate Dehydrogenase

The effects of organic osmolytes synthesised and accumulated by red algae from mangrove habitats were investigated on the in vitro activities of two major enzymes, one of the citric acid cycle (malate dehydrogenase, MDH) and one of the oxidative pentose phosphate pathway (glucose-6- phosphate dehydrogenase, G6PDH). These enzymes were extracted from the mangrove algae Bostrychia tenella, Caloglossa leprieurii, Catenella nipae and Stictosiphonia hookeri. In each case, activity of the enzymes was inhibited with increasing NaCl concentrations up to 600 mM . In contrast, equimolar concentrations of mannitol (the major osmolyte in C. leprieurii), sorbitol (the major osmolyte in B. Tenella and S. hookeri) and a heteroside mixture (of which floridoside is the major osmolyte in C. nipae) did not inhibit enzyme function. Dulcitol, the second most important organic osmolyte in B. tenella, exerted no negative effect at its maximum solubility of 180 rnM on the salt-sensitive MDH. These data are all consistent with the proposed function of these organic compounds as compatible solutes.

scholarly journals Compatible-Solute-Supported Periplasmic Expression of Functional Recombinant Proteins under Stress Conditions

2000 ◽  
Vol 66 (4) ◽  
pp. 1572-1579 ◽  
Author(s):  
S. Barth ◽  
M. Huhn ◽  
B. Matthey ◽  
A. Klimka ◽  
E. A. Galinski ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Recombinant Proteins ◽  
Glycine Betaine ◽  
Metal Ion ◽  
Halophilic Bacteria ◽  
Compatible Solutes ◽  
Compatible Solute ◽  
Size Exclusion ◽  
High Yield ◽  
High Concentrations

ABSTRACT The standard method of producing recombinant proteins such as immunotoxins (rITs) in large quantities is to transform gram-negative bacteria and subsequently recover the desired protein from inclusion bodies by intensive de- and renaturing procedures. The major disadvantage of this technique is the low yield of active protein. Here we report the development of a novel strategy for the expression of functional rIT directed to the periplasmic space of Escherichia coli. rITs were recovered by freeze-thawing of pellets from shaking cultures of bacteria grown under osmotic stress (4% NaCl plus 0.5 M sorbitol) in the presence of compatible solutes. Compatible solutes, such as glycine betaine and hydroxyectoine, are low-molecular-weight osmolytes that occur naturally in halophilic bacteria and are known to protect proteins at high salt concentrations. Adding 10 mM glycine betaine for the cultivation of E. coliunder osmotic stress not only allowed the bacteria to grow under these otherwise inhibitory conditions but also produced a periplasmic microenvironment for the generation of high concentrations of correctly folded rITs. Protein purified by combinations of metal ion affinity and size exclusion chromatography was substantially stabilized in the presence of 1 M hydroxyecotine after several rounds of freeze-thawing, even at very low protein concentrations. The binding properties and cytotoxic potency of the rITs were confirmed by competitive experiments. This novel compatible-solute-guided expression and purification strategy might also be applicable for high-yield periplasmic production of recombinant proteins in different expression systems.

scholarly journals Monitoring conformational changes during the catalytic cycle of OpuAA, the ATPase subunit of the ABC transporter OpuA from Bacillus subtilis

2008 ◽  
Vol 412 (2) ◽  
pp. 233-244 ◽  
Author(s):  
Carsten Horn ◽  
Stefan Jenewein ◽  
Britta Tschapek ◽  
Werner Bouschen ◽  
Sabine Metzger ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Abc Transporter ◽  
Conformational Changes ◽  
Compatible Solutes ◽  
Three Dimensional ◽  
Fine Tuning ◽  
Transport Systems ◽  
Dimensional Structure ◽  
Atpase Subunit ◽  
Accessory Domain

The ABC transporter (ATP-binding-cassette transporter) OpuA is one of five membrane transport systems in Bacillus subtilis that mediate osmoprotection by importing compatible solutes. Just like all bacterial and archaeal ABC transporters that catalyse the import of substrates, OpuA (where Opu is osmoprotectant uptake) is composed of an ATPase subunit (OpuAA), a transmembrane subunit (OpuAB) and an extracellular substrate-binding protein (OpuAC). In contrast with many well-known ABC-ATPases, OpuAA is composed not only of a catalytic and a helical domain but also of an accessory domain located at its C-terminus. The paradigm of such an architecture is MalK, the ABC-ATPase of the maltose importer of Escherichia coli, for which detailed structural and functional information is available. In the present study, we have applied solution FRET (Förster resonance energy transfer) techniques using two single cysteine mutants to obtain initial structural information on the architecture of the OpuAA dimer in solution. Analysing our results in detail and comparing them with the existing MalK structures revealed that the catalytic and helical domains adopted an arrangement similar to those of MalK, whereas profound differences in the three-dimensional orientation of the accessory domain, which contains two CBS (cystathionine β-synthetase) domains, were observed. These results shed new light on the role of this accessory domain present in a certain subset of ABC-ATPase in the fine-tuning of three-dimensional structure and biological function.

scholarly journals Osmotic Adaptation and Compatible Solute Biosynthesis of Phototrophic Bacteria as Revealed from Genome Analyses

2020 ◽  
Vol 9 (1) ◽  
pp. 46
Author(s):  
Johannes F. Imhoff ◽  
Tanja Rahn ◽  
Sven Künzel ◽  
Alexander Keller ◽  
Sven C. Neulinger
Keyword(s):  
Glycine Betaine ◽  
Compatible Solutes ◽  
Compatible Solute ◽  
Phototrophic Bacteria ◽  
Transport Systems ◽  
Phylogenetic Groups ◽  
Osmotic Adaptation ◽  
Cell Structures ◽  
Freshwater Bacteria ◽  
Genome Analyses

Osmotic adaptation and accumulation of compatible solutes is a key process for life at high osmotic pressure and elevated salt concentrations. Most important solutes that can protect cell structures and metabolic processes at high salt concentrations are glycine betaine and ectoine. The genome analysis of more than 130 phototrophic bacteria shows that biosynthesis of glycine betaine is common among marine and halophilic phototrophic Proteobacteria and their chemotrophic relatives, as well as in representatives of Pirellulaceae and Actinobacteria, but are also found in halophilic Cyanobacteria and Chloroherpeton thalassium. This ability correlates well with the successful toleration of extreme salt concentrations. Freshwater bacteria in general lack the possibilities to synthesize and often also to take up these compounds. The biosynthesis of ectoine is found in the phylogenetic lines of phototrophic Alpha- and Gammaproteobacteria, most prominent in the Halorhodospira species and a number of Rhodobacteraceae. It is also common among Streptomycetes and Bacilli. The phylogeny of glycine-sarcosine methyltransferase (GMT) and diaminobutyrate-pyruvate aminotransferase (EctB) sequences correlate well with otherwise established phylogenetic groups. Most significantly, GMT sequences of cyanobacteria form two major phylogenetic branches and the branch of Halorhodospira species is distinct from all other Ectothiorhodospiraceae. A variety of transport systems for osmolytes are present in the studied bacteria.

scholarly journals Effects of Temperature, Salinity, and Medium Composition on Compatible Solute Accumulation byThermococcus spp

1998 ◽  
Vol 64 (10) ◽  
pp. 3591-3598 ◽  
Author(s):  
Pedro Lamosa ◽  
Lígia O. Martins ◽  
Milton S. Da Costa ◽  
Helena Santos
Keyword(s):  
Compatible Solutes ◽  
Medium Composition ◽  
Compatible Solute ◽  
Resonance Spectroscopy ◽  
Thermococcus Litoralis ◽  
Solute Accumulation ◽  
Organic Solute ◽  
Low Levels ◽  
Effects Of Temperature ◽  
Thermococcus Celer

ABSTRACT The effects of salinity and growth temperature on the accumulation of intracellular organic solutes were examined by nuclear magnetic resonance spectroscopy (NMR) in Thermococcus litoralis,Thermococcus celer, Thermococcus stetteri, andThermococcus zilligii (strain AN1). In addition, the effects of growth stage and composition of the medium were studied inT. litoralis. A novel compound identified as β-galactopyranosyl-5-hydroxylysine was detected in T. litoralis grown on peptone-containing medium. Besides this newly discovered compound, T. litoralis accumulated mannosylglycerate, aspartate, α-glutamate, di-myo-inositol-1,1′(3,3′)-phosphate, hydroxyproline, and trehalose. The hydroxyproline and β-galactopyranosyl-5-hydroxylysine were probably derived from peptone, while the trehalose was derived from yeast extract; none of these three compounds was detected in the other Thermococcus strains examined. Di-myo-inositol-1,1′(3,3′)-phosphate, aspartate, and mannosylglycerate were detected in T. celer and T. stetteri, and the latter organism also accumulated α-glutamate. The only nonmarine species studied, T. zilligii, accumulated very low levels of α-glutamate and aspartate. The levels of mannosylglycerate and aspartate increased in T. litoralis, T. celer, and T. stetteri in response to salt stress, while di-myo-inositol-1,1′(3,3′)-phosphate was the major intracellular solute at supraoptimal growth temperatures. The phase of growth had a strong influence on the types and levels of compatible solutes in T. litoralis; mannosylglycerate and aspartate were the major solutes during exponential growth, while di-myo-inositol-1,1′(3,3′)-phosphate was the predominant organic solute during the stationary phase of growth. This work revealed an unexpected ability of T. litoralis to scavenge suitable components from the medium and to use them as compatible solutes.

scholarly journals The Compatible-Solute-Binding Protein OpuAC from Bacillus subtilis: Ligand Binding, Site-Directed Mutagenesis, and Crystallographic Studies

2008 ◽  
Vol 190 (16) ◽  
pp. 5663-5671 ◽  
Author(s):  
Sander H. J. Smits ◽  
Marina Höing ◽  
Justin Lecher ◽  
Mohamed Jebbar ◽  
Lutz Schmitt ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Mutational Analysis ◽  
Binding Protein ◽  
Substrate Binding ◽  
Compatible Solutes ◽  
Compatible Solute ◽  
Site Directed Mutagenesis ◽  
Transport Systems ◽  
The Past ◽  
Substrate Binding Protein

ABSTRACT In the soil bacterium Bacillus subtilis, five transport systems work in concert to mediate the import of various compatible solutes that counteract the deleterious effects of increases in the osmolarity of the environment. Among these five systems, the ABC transporter OpuA, which catalyzes the import of glycine betaine and proline betaine, has been studied in detail in the past. Here, we demonstrate that OpuA is capable of importing the sulfobetaine dimethylsulfonioacetate (DMSA). Since OpuA is a classic ABC importer that relies on a substrate-binding protein priming the transporter with specificity and selectivity, we analyzed the OpuA-binding protein OpuAC by structural and mutational means with respect to DMSA binding. The determined crystal structure of OpuAC in complex with DMSA at a 2.8-Å resolution and a detailed mutational analysis of these residues revealed a hierarchy within the amino acids participating in substrate binding. This finding is different from those for other binding proteins that recognize compatible solutes. Furthermore, important principles that enable OpuAC to specifically bind various compatible solutes were uncovered.

scholarly journals Examining the Osmotic Response of Acidihalobacter aeolianus after Exposure to Salt Stress

2021 ◽  
Vol 10 (1) ◽  
pp. 22
Author(s):  
Melissa K. Corbett ◽  
Liam Anstiss ◽  
April Gifford ◽  
Ross M. Graham ◽  
Elizabeth L. J. Watkin
Keyword(s):  
Osmotic Stress ◽  
Compatible Solutes ◽  
Organic Osmolytes ◽  
Osmotic Response ◽  
Environmental Instability ◽  
Acidic Environments ◽  
High Concentrations ◽  
Cellular Stresses ◽  
The Impact ◽  
Halophilic Species

Acidihalobacter aeolianus is an acidophilic, halo-tolerant organism isolated from a marine environment near a hydrothermal vent, an ecosystem whereby levels of salinity and total dissolved salts are constantly fluctuating creating ongoing cellular stresses. In order to survive these continuing changes, the synthesis of compatible solutes—also known as organic osmolytes—is suspected to occur, aiding in minimising the overall impact of environmental instability. Previous studies on A. aeolianus identified genes necessary for the accumulation of proline, betaine and ectoine, which are known to act as compatible solutes in other halophilic species. In this study, the impact of increasing the osmotic stress as well as the toxic ion effect was investigated by subjecting A. aeolianus to concentrations of NaCl and MgSO4 up to 1.27 M. Exposure to high concentrations of Cl- resulted in the increase of ectC expression in log-phase cells with a corresponding accumulation of ectoine at stationary phase. Osmotic stress via MgSO4 exposure did not trigger the same up-regulation of ectC or accumulation of ectoine, indicating the transcriptionally regulated response against osmotic stress was induced by chloride toxicity. These findings have highlighted how the adaptive properties of halo-tolerant organisms in acidic environments are likely to differ and are dependent on the initial stressor.

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