Role of Gluconeogenesis and the Tricarboxylic Acid Cycle in the Virulence of Salmonella enterica Serovar Typhimurium in BALB/c Mice

ABSTRACT In Salmonella enterica serovar Typhimurium, the Cra protein (catabolite repressor/activator) regulates utilization of gluconeogenic carbon sources by activating transcription of genes in the gluconeogenic pathway, the glyoxylate bypass, the tricarboxylic acid (TCA) cycle, and electron transport and repressing genes encoding glycolytic enzymes. A serovar Typhimurium SR-11 Δcra mutant was recently reported to be avirulent in BALB/c mice via the peroral route, suggesting that gluconeogenesis may be required for virulence. In the present study, specific SR-11 genes in the gluconeogenic pathway were deleted (fbp, glpX, ppsA, and pckA), and the mutants were tested for virulence in BALB/c mice. The data show that SR-11 does not require gluconeogenesis to retain full virulence and suggest that as yet unidentified sugars are utilized by SR-11 for growth during infection of BALB/c mice. The data also suggest that the TCA cycle operates as a full cycle, i.e., a sucCD mutant, which prevents the conversion of succinyl coenzyme A to succinate, and an ΔsdhCDA mutant, which blocks the conversion of succinate to fumarate, were both attenuated, whereas both an SR-11 ΔaspA mutant and an SR-11 ΔfrdABC mutant, deficient in the ability to run the reductive branch of the TCA cycle, were fully virulent. Moreover, although it appears that SR-11 replenishes TCA cycle intermediates from substrates present in mouse tissues, fatty acid degradation and the glyoxylate bypass are not required, since an SR-11 ΔfadD mutant and an SR-11 ΔaceA mutant were both fully virulent.

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Blocks in Tricarboxylic Acid Cycle of Salmonella enterica Cause Global Perturbation of Carbon Storage, Motility, and Host-Pathogen Interaction

mSphere ◽

10.1128/msphere.00796-19 ◽

2019 ◽

Vol 4 (6) ◽

Author(s):

Janina Noster ◽

Nicole Hansmeier ◽

Marcus Persicke ◽

Tzu-Chiao Chao ◽

Rainer Kurre ◽

...

Keyword(s):

Salmonella Enterica ◽

Tricarboxylic Acid Cycle ◽

Glycogen Synthesis ◽

Tca Cycle ◽

Carbon Fluxes ◽

Tricarboxylic Acid ◽

Cellular Functions ◽

Content Type ◽

Acid Cycle ◽

Serovar Typhimurium

ABSTRACT The tricarboxylic acid (TCA) cycle is a central metabolic hub in most cells. Virulence functions of bacterial pathogens such as facultative intracellular Salmonella enterica serovar Typhimurium (S. Typhimurium) are closely connected to cellular metabolism. During systematic analyses of mutant strains with defects in the TCA cycle, a strain deficient in all fumarase isoforms (ΔfumABC) elicited a unique metabolic profile. Alongside fumarate, S. Typhimurium ΔfumABC accumulates intermediates of the glycolysis and pentose phosphate pathway. Analyses by metabolomics and proteomics revealed that fumarate accumulation redirects carbon fluxes toward glycogen synthesis due to high (p)ppGpp levels. In addition, we observed reduced abundance of CheY, leading to altered motility and increased phagocytosis of S. Typhimurium by macrophages. Deletion of glycogen synthase restored normal carbon fluxes and phagocytosis and partially restored levels of CheY. We propose that utilization of accumulated fumarate as carbon source induces a status similar to exponential- to stationary-growth-phase transition by switching from preferred carbon sources to fumarate, which increases (p)ppGpp levels and thereby glycogen synthesis. Thus, we observed a new form of interplay between metabolism of S. Typhimurium and cellular functions and virulence. IMPORTANCE We performed perturbation analyses of the tricarboxylic acid cycle of the gastrointestinal pathogen Salmonella enterica serovar Typhimurium. The defect of fumarase activity led to accumulation of fumarate but also resulted in a global alteration of carbon fluxes, leading to increased storage of glycogen. Gross alterations were observed in proteome and metabolome compositions of fumarase-deficient Salmonella. In turn, these changes were linked to aberrant motility patterns of the mutant strain and resulted in highly increased phagocytic uptake by macrophages. Our findings indicate that basic cellular functions and specific virulence functions in Salmonella critically depend on the proper function of the primary metabolism.

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Salmonella enterica Serovar Typhimurium Mutants Unable To Convert Malate to Pyruvate and Oxaloacetate Are Avirulent and Immunogenic in BALB/c Mice

Infection and Immunity ◽

10.1128/iai.01335-08 ◽

2009 ◽

Vol 77 (4) ◽

pp. 1397-1405 ◽

Cited By ~ 23

Author(s):

Regino Mercado-Lubo ◽

Mary P. Leatham ◽

Tyrrell Conway ◽

Paul S. Cohen

Keyword(s):

Salmonella Enterica ◽

Type Strain ◽

Wild Type Strain ◽

Salmonella Enterica Serovar Typhimurium ◽

Tca Cycle ◽

Tricarboxylic Acid ◽

Oral Infection ◽

Wild Type ◽

The Tca Cycle ◽

Serovar Typhimurium

ABSTRACT Previously, we showed that the Salmonella enterica serovar Typhimurium SR-11 tricarboxylic acid (TCA) cycle must operate as a complete cycle for full virulence after oral infection of BALB/c mice (M. Tchawa Yimga, M. P. Leatham, J. H. Allen, D. C. Laux, T. Conway, and P. S. Cohen, Infect. Immun. 74:1130-1140, 2006). In the same study, we showed that for full virulence, malate must be converted to both oxaloacetate and pyruvate. Moreover, it was recently demonstrated that blocking conversion of succinyl-coenzyme A to succinate attenuates serovar Typhimurium SR-11 but does not make it avirulent; however, blocking conversion of succinate to fumarate renders it completely avirulent and protective against subsequent oral infection with the virulent serovar Typhimurium SR-11 wild-type strain (R. Mercado-Lubo, E. J. Gauger, M. P. Leatham, T. Conway, and P. S. Cohen, Infect. Immun. 76:1128-1134, 2008). Furthermore, the ability to convert succinate to fumarate appeared to be required only after serovar Typhimurium SR-11 became systemic. In the present study, evidence is presented that serovar Typhimurium SR-11 mutants that cannot convert fumarate to malate or that cannot convert malate to both oxaloacetate and pyruvate are also avirulent and protective in BALB/c mice. These results suggest that in BALB/c mice, the malate that is removed from the TCA cycle in serovar Typhimurium SR-11 for conversion to pyruvate must be replenished by succinate or one of its precursors, e.g., arginine or ornithine, which might be available in mouse phagocytes.

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Genetic and Biochemical Interactions Involving Tricarboxylic Acid Cycle (TCA) Function Using a Collection of Mutants Defective in All TCA Cycle Genes

Genetics ◽

10.1093/genetics/152.1.153 ◽

1999 ◽

Vol 152 (1) ◽

pp. 153-166 ◽

Cited By ~ 1

Author(s):

Beata Przybyla-Zawislak ◽

Devi M Gadde ◽

Kurt Ducharme ◽

Mark T McCammon

Keyword(s):

Citrate Synthase ◽

Tricarboxylic Acid Cycle ◽

Carbon Sources ◽

Tca Cycle ◽

Tricarboxylic Acid ◽

Gene Encoding ◽

Unique Role ◽

Yeast Strains ◽

The Tca Cycle ◽

Mutant Collection

Abstract The eight enzymes of the tricarboxylic acid (TCA) cycle are encoded by at least 15 different nuclear genes in Saccharomyces cerevisiae. We have constructed a set of yeast strains defective in these genes as part of a comprehensive analysis of the interactions among the TCA cycle proteins. The 15 major TCA cycle genes can be sorted into five phenotypic categories on the basis of their growth on nonfermentable carbon sources. We have previously reported a novel phenotype associated with mutants defective in the IDH2 gene encoding the Idh2p subunit of the NAD+-dependent isocitrate dehydrogenase (NAD-IDH). Null and nonsense idh2 mutants grow poorly on glycerol, but growth can be enhanced by extragenic mutations, termed glycerol suppressors, in the CIT1 gene encoding the TCA cycle citrate synthase and in other genes of oxidative metabolism. The TCA cycle mutant collection was utilized to search for other genes that can suppress idh2 mutants and to identify TCA cycle genes that display a similar suppressible growth phenotype on glycerol. Mutations in 7 TCA cycle genes were capable of functioning as suppressors for growth of idh2 mutants on glycerol. The only other TCA cycle gene to display the glycerol-suppressor-accumulation phenotype was IDH1, which encodes the companion Idh1p subunit of NAD-IDH. These results provide genetic evidence that NAD-IDH plays a unique role in TCA cycle function.

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Staphylococcus epidermidis Polysaccharide Intercellular Adhesin Production Significantly Increases during Tricarboxylic Acid Cycle Stress

Journal of Bacteriology ◽

10.1128/jb.187.9.2967-2973.2005 ◽

2005 ◽

Vol 187 (9) ◽

pp. 2967-2973 ◽

Cited By ~ 71

Author(s):

Cuong Vuong ◽

Joshua B. Kidder ◽

Erik R. Jacobson ◽

Michael Otto ◽

Richard A. Proctor ◽

...

Keyword(s):

Staphylococcus Epidermidis ◽

Tricarboxylic Acid Cycle ◽

Tca Cycle ◽

Redox Status ◽

Tricarboxylic Acid ◽

Polysaccharide Intercellular Adhesin ◽

Low Oxygen ◽

Acid Cycle ◽

The Tca Cycle ◽

High Concentrations

ABSTRACT Staphylococcal polysaccharide intercellular adhesin (PIA) is important for the development of a mature biofilm. PIA production is increased during growth in a nutrient-replete or iron-limited medium and under conditions of low oxygen availability. Additionally, stress-inducing stimuli such as heat, ethanol, and high concentrations of salt increase the production of PIA. These same environmental conditions are known to repress tricarboxylic acid (TCA) cycle activity, leading us to hypothesize that altering TCA cycle activity would affect PIA production. Culturing Staphylococcus epidermidis with a low concentration of the TCA cycle inhibitor fluorocitrate dramatically increased PIA production without impairing glucose catabolism, the growth rate, or the growth yields. These data lead us to speculate that one mechanism by which staphylococci perceive external environmental change is through alterations in TCA cycle activity leading to changes in the intracellular levels of biosynthetic intermediates, ATP, or the redox status of the cell. These changes in the metabolic status of the bacteria result in the attenuation or augmentation of PIA production.

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Metabolic engineering of Bacillus amyloliquefaciens for enhanced production of S-adenosylmethionine by coupling of an engineered S-adenosylmethionine pathway and the tricarboxylic acid cycle

Biotechnology for Biofuels ◽

10.1186/s13068-019-1554-0 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 3

Author(s):

Liying Ruan ◽

Lu Li ◽

Dian Zou ◽

Cong Jiang ◽

Zhiyou Wen ◽

...

Keyword(s):

Metabolic Engineering ◽

Bacillus Amyloliquefaciens ◽

Tricarboxylic Acid Cycle ◽

Fold Increase ◽

Tca Cycle ◽

Tricarboxylic Acid ◽

Scale Production ◽

Free Medium ◽

Enhanced Production ◽

The Tca Cycle

Abstract Background S-Adenosylmethionine (SAM) is a critical cofactor involved in many biochemical reactions. However, the low fermentation titer of SAM in methionine-free medium hampers commercial-scale production. The SAM synthesis pathway is specially related to the tricarboxylic acid (TCA) cycle in Bacillus amyloliquefaciens. Therefore, the SAM synthesis pathway was engineered and coupled with the TCA cycle in B. amyloliquefaciens to improve SAM production in methionine-free medium. Results Four genes were found to significantly affect SAM production, including SAM2 from Saccharomyces cerevisiae, metA and metB from Escherichia coli, and native mccA. These four genes were combined to engineer the SAM pathway, resulting in a 1.42-fold increase in SAM titer using recombinant strain HSAM1. The engineered SAM pathway was subsequently coupled with the TCA cycle through deletion of succinyl-CoA synthetase gene sucC, and the resulted HSAM2 mutant produced a maximum SAM titer of 107.47 mg/L, representing a 0.59-fold increase over HSAM1. Expression of SAM2 in this strain via a recombinant plasmid resulted in strain HSAM3 that produced 648.99 mg/L SAM following semi-continuous flask batch fermentation, a much higher yield than previously reported for methionine-free medium. Conclusions This study reports an efficient strategy for improving SAM production that can also be applied for generation of SAM cofactors supporting group transfer reactions, which could benefit metabolic engineering, chemical biology and synthetic biology.

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A Salmonella enterica Serovar Typhimurium Succinate Dehydrogenase/Fumarate Reductase Double Mutant Is Avirulent and Immunogenic in BALB/c Mice

Infection and Immunity ◽

10.1128/iai.01226-07 ◽

2007 ◽

Vol 76 (3) ◽

pp. 1128-1134 ◽

Cited By ~ 32

Author(s):

Regino Mercado-Lubo ◽

Eric J. Gauger ◽

Mary P. Leatham ◽

Tyrrell Conway ◽

Paul S. Cohen

Keyword(s):

Succinate Dehydrogenase ◽

Salmonella Enterica ◽

Double Mutant ◽

Wild Type Strain ◽

Salmonella Enterica Serovar Typhimurium ◽

Tca Cycle ◽

Fumarate Reductase ◽

Subsequent Infection ◽

The Tca Cycle ◽

Serovar Typhimurium

ABSTRACT Previously we showed that the tricarboxylic acid (TCA) cycle operates as a full cycle during Salmonella enterica serovar Typhimurium SR-11 peroral infection of BALB/c mice (M. Tchawa Yimga et al., Infect. Immun. 74:1130-1140, 2006). The evidence was that a ΔsucCD mutant (succinyl coenzyme A [succinyl-CoA] synthetase), which prevents the conversion of succinyl-CoA to succinate, and a ΔsdhCDA mutant (succinate dehydrogenase), which blocks the conversion of succinate to fumarate, were both attenuated, whereas an SR-11 ΔaspA mutant (aspartase) and an SR-11 ΔfrdABCD mutant (fumarate reductase), deficient in the ability to run the reductive branch of the TCA cycle, were fully virulent. In the present study, evidence is presented that a serovar Typhimurium SR-11 ΔfrdABCD ΔsdhCDA double mutant is avirulent in BALB/c mice and protective against subsequent infection with the virulent serovar Typhimurium SR-11 wild-type strain via the peroral route and is highly attenuated via the intraperitoneal route. These results suggest that fumarate reductase, which normally runs in the reductive pathway in the opposite direction of succinate dehydrogenase, can replace it during infection by running in the same direction as succinate dehydrogenase in order to run a full TCA cycle in an SR-11 ΔsdhCDA mutant. The data also suggest that the conversion of succinate to fumarate plays a key role in serovar Typhimurium virulence. Moreover, the data raise the possibility that S. enterica ΔfrdABCD ΔsdhCDA double mutants and ΔfrdABCD ΔsdhCDA double mutants of other intracellular bacterial pathogens with complete TCA cycles may prove to be effective live vaccine strains for animals and humans.

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Metabolism of glucose-14C, pyruvate-14C, and mannitol-14C by Melampsora lini. II. Conversion to soluble products

Canadian Journal of Botany ◽

10.1139/b68-069 ◽

1968 ◽

Vol 46 (4) ◽

pp. 453-460 ◽

Cited By ~ 10

Author(s):

D. Mitchell ◽

Michael Shaw

Keyword(s):

Pentose Phosphate Pathway ◽

Tricarboxylic Acid Cycle ◽

Rust Fungus ◽

Tca Cycle ◽

Tricarboxylic Acid ◽

Pentose Phosphate ◽

Soluble Carbohydrates ◽

Melampsora Lini ◽

Carbohydrate Fraction ◽

The Tca Cycle

Mycelium of the flax rust fungus (Melampsora lini (Pers.) Lév.), grown on flax cotyledons in tissue culture, had a mean [Formula: see text]of 4.1 and a mean C6/C1 ratio of 0.14, measured after 4 hours in radioactive glucose. The C6/C1 ratio increased with time and also after treatment with 10−5 M 2,4-dinitrophenol. The relative labelling of the (80%) ethanol-soluble carbohydrates, and organic and amino acid fractions after incubation with glucose-1-, -2-, or -6-14C also indicated preferential release of C1 as 14CO2. Trehalose (unknown A) was tentatively identified in the carbohydrate fraction and was mildly radioactive after incubation of the mycelium with labelled glucose for 3 hours. The principal radioactive products of glucose in this fraction were two unknowns, B and C, which were tentatively identified as mannitol and arabitol. The labelling patterns were consistent with their formation from intermediates of the pentose phosphate pathway. The distribution of radioactivity derived from glucose in alanine, glutamate, and aspartate also indicated that hexose or triose units formed in the pentose phosphate pathway were converted to pyruvate, which either gave rise to alanine or was further oxidized in the tricarboxylic acid cycle. Incubation with pyruvate-1-, -2-, or -3-14C for 3 hours gave rise to 14CO2 and labelled alanine, glutamate, and aspartate in a manner consistent with the operation of the TCA cycle. Mannitol-1-6-14C was not metabolized to any appreciable extent in this period, but did give rise to 14CO2 and to several unidentified compounds in the carbohydrate fraction.

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rre37Overexpression Alters Gene Expression Related to the Tricarboxylic Acid Cycle and Pyruvate Metabolism inSynechocystissp. PCC 6803

The Scientific World JOURNAL ◽

10.1155/2014/921976 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10 ◽

Cited By ~ 4

Author(s):

Hiroko Iijima ◽

Atsuko Watanabe ◽

Junko Takanobu ◽

Masami Yokota Hirai ◽

Takashi Osanai

Keyword(s):

Gene Expression ◽

Response Regulator ◽

Tricarboxylic Acid Cycle ◽

Tca Cycle ◽

Tricarboxylic Acid ◽

Nitrogen Depletion ◽

Pyruvate Metabolism ◽

Unicellular Cyanobacterium ◽

The Tca Cycle ◽

In The Wild

The tricarboxylic acid (TCA) cycle and pyruvate metabolism of cyanobacteria are unique and important from the perspectives of biology and biotechnology research. Rre37, a response regulator induced by nitrogen depletion, activates gene expression related to sugar catabolism. Our previous microarray analysis has suggested that Rre37 controls the transcription of genes involved in sugar catabolism, pyruvate metabolism, and the TCA cycle. In this study, quantitative real-time PCR was used to measure the transcript levels of 12 TCA cycle genes and 13 pyruvate metabolism genes. The transcripts of 6 genes (acnB,icd,ppc,pyk1,me, andpta) increased after 4 h of nitrogen depletion in the wild-type GT strain but the induction was abolished byrre37overexpression. The repression of gene expression offumC, ddh, andackAcaused by nitrogen depletion was abolished byrre37overexpression. The expression ofmewas differently affected byrre37overexpression, compared to the other 24 genes. These results indicate that Rre37 differently controls the genes of the TCA cycle and pyruvate metabolism, implying the key reaction of the primary in this unicellular cyanobacterium.

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Tricarboxylic Acid (TCA) Cycle Intermediates: Regulators of Immune Responses

10.20944/preprints202012.0810.v1 ◽

2020 ◽

Author(s):

Inseok Choi ◽

Hyewon Son ◽

Jea-Hyun Baek

Keyword(s):

Immune Responses ◽

Molecular Mechanisms ◽

Tricarboxylic Acid Cycle ◽

Tca Cycle ◽

Tricarboxylic Acid ◽

Cell Stress ◽

Danger Signals ◽

Cellular Processes ◽

The Tca Cycle ◽

Tca Cycle Intermediates

Tricarboxylic acid cycle (TCA) is a series of chemical reactions in aerobic organisms used to generate energy via the oxidation of acetyl-CoA derived from carbohydrates, fatty acids, and proteins. In the eukaryotic system, the TCA cycle completely occurs in mitochondria, while the intermediates of the TCA cycle are retained in mitochondria due to their polarity and hydrophilicity. Under conditions of cell stress, mitochondria become disrupted and release their contents, which act as danger signals in the cytosol. Of note, the TCA cycle intermediates may also leak from dysfunctioning mitochondria and regulate cellular processes. Increasing evidence shows that the metabolites of the TCA cycle are substantially involved in the regulation of immune responses. In this review, we aimed to provide a comprehensive systematic overview of the molecular mechanisms of each TCA cycle intermediate that may play key roles in regulating cellular immunity in cell stress and discuss their implications for immune activation and suppression.

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Trehalose-6-phosphate links singlet oxygen-induced signalling with metabolic signalling in Chlamydomonas reinhardtii

10.1101/2021.11.03.467076 ◽

2021 ◽

Author(s):

Waeil Al Youssef ◽

Regina Feil ◽

Maureen Saint-Sorny ◽

Xenie Johnson ◽

John E. Lunn ◽

...

Keyword(s):

Singlet Oxygen ◽

Chlamydomonas Reinhardtii ◽

Tricarboxylic Acid Cycle ◽

Cell Metabolism ◽

Tca Cycle ◽

Tricarboxylic Acid ◽

Metabolic Signalling ◽

Retrograde Signalling ◽

Essential Components ◽

Genes Encoding

Singlet oxygen (1O2) induces retrograde signalling in chloroplasts. Using a novel mutant screen, we identified a mutation in the TREHALOSE-6-PHOSPHATE PHOSPHATASE 1 (T6PP1) gene that results in accumulation of trehalose 6-phosphate, a reprogramming of cell metabolism, and impairment of 1O2-induced retrograde signalling in Chlamydomonas reinhardtii. From transcriptomic analysis and metabolite profiling, we conclude that accumulation or deficiency of certain metabolites directly affect 1O2-signalling. 1O2-inducible GLUTATHIONE PEROXIDASE 5 (GPX5) gene expression is suppressed by increased content of fumarate, an intermediate in the tricarboxylic acid cycle (TCA cycle) in mitochondria and dicarboxylate metabolism in the cytosol, while it is promoted by another TCA cycle intermediate, aconitate. Furthermore, genes encoding known essential components of chloroplast-to-nucleus 1O2-signalling show decreased transcript levels in a t6pp1 mutant, which can be rescued by exogenous application of aconitate. We demonstrate that chloroplast retrograde signalling involving 1O2 depends on mitochondrial and cytosolic processes and that the metabolic status of the cell determines the response to 1O2.

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