Potassium glutamate as a transcriptional inhibitor during bacterial osmoregulation

Gralla, Jay D.; Vargas, David Robert

doi:10.1038/sj.emboj.7601041

Cited by 89 publications

(113 citation statements)

References 32 publications

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“…Internal glutamate is then used as a "second messenger" for the induction of proline biosynthesis genes. In the group of Gralla, several studies were done demonstrating the potential of glutamate to activate or inhibit transcription (10,15). This is in perfect correlation with our studies, where a minimal external glutamate concentration of 200 mM (at a total salinity of 2 M) effectively stimulates the transcription of the pro genes.…”

Section: Discussionsupporting

confidence: 73%

Salinity-Dependent Switching of Osmolyte Strategies in a Moderately Halophilic Bacterium: Glutamate Induces Proline Biosynthesis in Halobacillus halophilus

2007

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. 188:6808-6815, 2006). Here, we report that H. halophilus switches its osmolyte strategy and produces proline as the dominant solute at higher salinities (2 to 3 M NaCl). The proline biosynthesis genes proH, proJ, and proA were identified. They form a transcriptional unit and encode the pyrroline-5-carboxylate reductase, the glutamate-5-kinase, and the glutamate-5-semialdehyde dehydrogenase, respectively, catalyzing proline biosynthesis from glutamate. Expression of the genes was clearly salinity dependent and reached a maximum at 2.5 M NaCl, indicating that the pro operon is involved in salinity-induced proline biosynthesis. To address the role of anions in the process of pro gene activation and proline biosynthesis, we used a cell suspension system. Chloride salts lead to the highest accumulation of proline. Interestingly, chloride could be substituted to a large extent by glutamate salts. This unexpected finding was further analyzed on the transcriptional level. The cellular mRNA levels of all three pro genes were increased up to 90-fold in the presence of glutamate. A titration revealed that a minimal concentration of 0.2 M glutamate already stimulated pro gene expression. These data demonstrate that the solute glutamate is involved in the switch of osmolyte strategy from glutamate to proline as the dominant compatible solute during the transition from moderate to high salinity.

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Section: Discussionsupporting

confidence: 73%

Salinity-Dependent Switching of Osmolyte Strategies in a Moderately Halophilic Bacterium: Glutamate Induces Proline Biosynthesis in Halobacillus halophilus

2007

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“…In both Gram-negative and Gram-positive bacteria, potassium glutamate has been linked to osmoregulation (18,28). In E. coli, accumulation of potassium glutamate immediately after osmotic shock provides temporary protection to the cells and either inhibits gene transcription by directly inhibiting RNA polymerase binding or increases transcription by acting through sigma-38 or by direct interaction on select gene promoters (18).…”

Section: Figmentioning

confidence: 99%

“…In E. coli, accumulation of potassium glutamate immediately after osmotic shock provides temporary protection to the cells and either inhibits gene transcription by directly inhibiting RNA polymerase binding or increases transcription by acting through sigma-38 or by direct interaction on select gene promoters (18). In Oenococcus oeni, glutamate-containing peptides confer protection from salt-induced osmotic stress (28), and in Bacillus subtilis it is speculated that osmotic stress may result in an enhanced requirement for glutamate to generate an increased level of the known osmoprotectant proline (23).…”

Section: Figmentioning

confidence: 99%

Characterization of a Glutamate Transporter Operon, glnQHMP , in Streptococcus mutans and Its Role in Acid Tolerance

et al. 2010

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Glutamate contributes to the acid tolerance response (ATR) of many Gram-negative and Gram-positive bacteria, but its role in the ATR of the oral bacterium Streptococcus mutans is unknown. This study describes the discovery and characterization of a glutamate transporter operon designated glnQHMP (Smu.1519 to Smu.1522) and investigates its potential role in acid tolerance. Deletion of glnQHMP resulted in a 95% reduction in transport of radiolabeled glutamate compared to the wild-type UA159 strain. The addition of glutamate to metabolizing UA159 cells resulted in an increased production of acidic end products, whereas the glnQHMP mutant produced less lactic acid than UA159, suggesting a link between glutamate metabolism and acid production and possible acid tolerance. To investigate this possibility, we conducted a microarray analysis with glutamate and under pH 5.5 and pH 7.5 conditions which showed that expression of the glnQHMP operon was downregulated by both glutamate and mild acid. We also measured the growth kinetics of UA159 and its glnQHMP-negative derivative at pH 5.5 and found that the mutant doubled at a much slower rate than the parent strain but survived at pH 3.5 significantly better than the wild type. Taken together, these findings support the involvement of the glutamate transporter operon glnQHMP in the acid tolerance response in S. mutans.

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“…GDH may produce glutamate to enhance protein-DNA interactions (e.g., see reference 610) or, together with potassium, to act differentially on cellular promoters so as to activate some or inhibit others (611).…”

Section: Gs Gogat and Gdh Functionsmentioning

confidence: 99%

Nitrogen Assimilation in Escherichia coli: Putting Molecular Data into a Systems Perspective

Heeswijk¹,

Westerhoff

Boogerd³

2013

Microbiol Mol Biol Rev

232

246

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SUMMARY We present a comprehensive overview of the hierarchical network of intracellular processes revolving around central nitrogen metabolism in Escherichia coli . The hierarchy intertwines transport, metabolism, signaling leading to posttranslational modification, and transcription. The protein components of the network include an ammonium transporter (AmtB), a glutamine transporter (GlnHPQ), two ammonium assimilation pathways (glutamine synthetase [GS]-glutamate synthase [glutamine 2-oxoglutarate amidotransferase {GOGAT}] and glutamate dehydrogenase [GDH]), the two bifunctional enzymes adenylyl transferase/adenylyl-removing enzyme (ATase) and uridylyl transferase/uridylyl-removing enzyme (UTase), the two trimeric signal transduction proteins (GlnB and GlnK), the two-component regulatory system composed of the histidine protein kinase nitrogen regulator II (NRII) and the response nitrogen regulator I (NRI), three global transcriptional regulators called nitrogen assimilation control (Nac) protein, leucine-responsive regulatory protein (Lrp), and cyclic AMP (cAMP) receptor protein (Crp), the glutaminases, and the nitrogen-phosphotransferase system. First, the structural and molecular knowledge on these proteins is reviewed. Thereafter, the activities of the components as they engage together in transport, metabolism, signal transduction, and transcription and their regulation are discussed. Next, old and new molecular data and physiological data are put into a common perspective on integral cellular functioning, especially with the aim of resolving counterintuitive or paradoxical processes featured in nitrogen assimilation. Finally, we articulate what still remains to be discovered and what general lessons can be learned from the vast amounts of data that are available now.

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Potassium glutamate as a transcriptional inhibitor during bacterial osmoregulation

Cited by 89 publications

References 32 publications

Salinity-Dependent Switching of Osmolyte Strategies in a Moderately Halophilic Bacterium: Glutamate Induces Proline Biosynthesis in Halobacillus halophilus

Salinity-Dependent Switching of Osmolyte Strategies in a Moderately Halophilic Bacterium: Glutamate Induces Proline Biosynthesis in Halobacillus halophilus

Characterization of a Glutamate Transporter Operon, glnQHMP , in Streptococcus mutans and Its Role in Acid Tolerance

Nitrogen Assimilation in Escherichia coli: Putting Molecular Data into a Systems Perspective

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