Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Catabolite Repression”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources
PubMed1997

Carbon-source regulation of virulence gene expression in Listeria monocytogenes.

All known virulence genes of Listeria monocytogenes are under positive regulation by the transcription factor PrfA. Previous work employing the L. monocytogenes strain NCTC7973 suggested that the disaccharide cellobiose might serve as a specific "signature molecule' which functions to prevent activation of the PrfA-controlled regulon in a soil environment. We have examined three other L. monocytogenes strains, 10403S, LO28 and EGD, all commonly regarded as wild-type isolates, and find that NCTC7973 is anomalous with respect to the effect of carbohydrates on the expression of PrfA-controlled gene expression. In the case of 10403S, LO28 and EGD, several other readily metabolized mono- and disaccharides are as effective as cellobiose in repressing expression of the PrfA-controlled gene hly, indicating that the cellobiose effect is not specific, and suggesting that NCTC7973 may be a partially deregulated variant. Moreover, concentrations of cellobiose and other sugars required for repression of hly expression (> 1 mM) were found to significantly enhance growth of L. monocytogenes cultures, suggesting that the repression phenomenon probably results from a metabolic effect of sugar utilization rather than a signal-sensing response. Thus the previously reported cellobiose effect may reflect an aspect of a more global mechanism of catabolite repression in L. monocytogenes. Although cellobiose represses expression of hly and plcA at the level of transcript accumulation, quantitative Western blot analysis indicates that cellobiose has no effect on PrfA levels. These results are consistent with a model in which PrfA activity is controlled by interaction with a hypothetical cofactor, the synthesis or depletion of which is responsive to the presence of readily metabolized carbohydrates.

Bacterial Proteins↗
PubMed1990

The effects of anthranilic acid on gene expression.

1. A Drosophila pseudoobscura amylase gene cloned in Escherichia coli is expressed at high levels. The expression of this gene is repressed when glucose (0.5% final concentration) is added to a starch minimal medium culture of E. coli cells containing the amylase plasmid. 2. Addition of anthranilic acid (5 and 7 mM final exogenous concentration) to catabolite repressed cells mimics the action of adenosine 3'5' cyclic monophosphate (cAMP) by depressing the expression of the amylase. 3. The results suggest that anthranilic acid acts either indirectly, possibly through the glucose transport system, or directly, by way of an intercalative model of initiation, to alter the levels of transcription.

Amylases↗
PubMed1987

The effect of nitrogen and carbon sources on proteinase production by Pseudomonas fluorescens.

Some factors influencing the production of an extracellular proteinase by Pseudomonas fluorescens NCDO 2085 were studied. Proteinase production was optimal at 20 degrees C and pH 6.9 in static culture when calcium was included in the medium. Proteinase was not detectable in basal medium but could be induced by organic nitrogen compounds. The proteinase was produced in the exponential phase of growth on protein substrates but not until early stationary phase during growth on amino acids. The organism did not utilize lactose, the most abundant carbohydrate in milk. Citrate was readily utilized as an energy source but had a strong repressive effect on proteinase production. A medium containing sodium caseinate and pyruvate supported good growth and enzyme production. All the amino acids utilized as a sole carbon source, with the exception of serine, could induce proteinase production. Asparagine was the most effective amino acid inducer. Particular combinations of amino acids could induce or repress proteinase production. The regulation of proteinase production by Ps. fluorescens NCDO 2085 appears to be based on a balance between induction by low concentrations of low molecular weight degradation products and sensitivity to end product catabolite repression. The results suggest that the function of the proteinase is to ensure a supply of carbon rather than amino acids for protein synthesis.

Amino Acids↗
PubMed1987

Regulation of fructose uptake and catabolism by succinate in Azospirillum brasilense.

Fructose uptake and catabolism in Azospirillum brasilense is dependent on three fructose-inducible enzymes (fru-enzymes): (i) enzyme I and (ii) enzyme II of the phosphoenolpyruvate:fructose phosphotransferase system and (iii) 1-phosphofructokinase. In minimal medium containing 3.7 mM succinate and 22 mM fructose as sources of carbon, growth of A. brasilense was diauxic, succinate being utilized in the first phase of growth and fructose in the second phase with a lag period between the two growth phases. None of the fru-enzymes could be detected in cells grown with succinate as the sole source of carbon, but they were detectable toward the end of the first phase of diauxie. All the fru-enzymes were coinduced by fructose and coordinately repressed by succinate. Studies on the effect of succinate on differential rates of syntheses of the fru-enzymes revealed that their induced syntheses in fructose minimal medium were subject to transient as well as permanent (catabolite) repression by succinate. Succinate also caused a similar pattern of transient and permanent repression of the fructose transport system in A. brasilense. However, no inducer (fructose) exclusionlike effect was observed as there was no inhibition of fructose uptake in the presence of succinate with fructose-grown cells even when they were fully induced for succinate uptake activity.

Culture Media↗
PubMed1995

In vivo induction kinetics of the arabinose promoters in Escherichia coli.

In Escherichia coli, the AraC protein represses transcription from its own promoter, PC, and when associated with arabinose, activates transcription from three other promoters, PBAD, PE, and PFGH. Expression from all four of these promoters is also regulated by cyclic AMP-catabolite activator protein; however, the arrangement of the protein binding sites is not identical for each promoter. We are interested in determining how the AraC protein is able to activate PBAD, PE, and PFGH despite their differences. We have characterized the induction response of the wild-type arabinose operons from their native chromosomal locations by primer extension analysis. In this analysis, mRNA from the four arabinose operons plus an internal standard could all be assayed in the RNA obtained from a single sample of cells. We found that each of the operons shows a rapid, within 15 to 30 s, response to arabinose. We also found that the expression of araFGH is more sensitive to catabolite repression but not to arabinose concentration than are araE and araBAD. Finally, we have determined the relative levels of inducibility in wild-type cells of araBAD, araFGH, and araE to be 6.5, 5, and 1, respectively. These results provide a basis for subsequent studies to determine the mechanism(s) by which AraC protein activates transcription from the different arabinose promoters.

AraC Transcription Factor↗
PubMed2005

Glucose repression of the Escherichia coli sdhCDAB operon, revisited: regulation by the CRP*cAMP complex.

Expression of the Escherichia coli sdhCDAB operon encoding the succinate dehydrogenase complex is regulated in response to growth conditions, such as anaerobiosis and carbon sources. An anaerobic repression of sdhCDAB is known to be mediated by the ArcB/A two-component system and the global Fnr anaerobic regulator. While the cAMP receptor protein (CRP) and Cra (formerly FruR) are known as key mediators of catabolite repression, they have been excluded from the glucose repression of the sdhCDAB operon. Although the glucose repression of sdhCDAB was reported to involve a mechanism dependent on the ptsG expression, the molecular mechanism underlying the glucose repression has never been clarified. In this study, we re-examined the mechanism of the sdhCDAB repression by glucose and found that CRP directly regulates expression of the sdhCDAB operon and that the glucose repression of this operon occurs in a cAMP-dependent manner. The levels of phosphorylated enzyme IIA(Glc) and intracellular cAMP on various carbon sources were proportional to the expression levels of sdhC-lacZ. Disruption of crp or cya completely abolished the glucose repression of sdhC-lacZ expression. Together with data showing correlation between the intracellular cAMP concentrations and the sdhC-lacZ expression levels in several mutants and wild type, in vitro transcription assays suggest that the decrease in the CRP.cAMP level in the presence of glucose is the major determinant of the glucose repression of the sdhCDAB operon.

Bacterial Proteins↗
PubMed1989

Genetic regulation of the tricarboxylate transport operon (tctI) of Salmonella typhimurium.

Tricarboxylates are transported into Salmonella typhimurium by a binding protein-dependent transport system known as TctI. Genetically, it comprises three structural genes, tctCBA, as well as a fourth gene of unknown function (tctD), which is transcribed divergently from tctC (K. A. Widenhorn, J. M. Somers, and W. W. Kay, J. Bacteriol. 170:3223-3227, 1988). Deletions in tctD strongly reduced expression of tctC or of tctC-lacZ transcriptional fusions; however, expression was restored when tctD was present in trans. Expression of tctD-lacZ transcriptional fusions was strongly repressed in the presence of D-glucose but could be alleviated by the addition of cyclic AMP. Furthermore, transcription of tctD was found not to be autogenously regulated. Thus, tctD is considered to be regulated by catabolite repression and encodes a transcriptional activator of tctCBA expression. From the DNA sequence of tctD, the predicted gene product was hydrophilic and shared distinct homologies with other globally regulated transcriptional activators such as OmpR and NtrC.

Amino Acid Sequence↗
PubMed1990

[The effect of specific mutation crp a in the genetic locus of receptor protein cAMP (CRP) on the expression of Escherichia coli K-12 deo-operon].

Expression of the deo operon of Escherichia coli is subjected to double negative control by DeoR and CytR repressors and to the positive control by cAMP-CRP complex. However, sensitivity of the deo operon to catabolite repression is only revealed in bacteria with disrupted synthesis of the CytR protein, since the function of the latter is to prevent CRP activation of the deo operon transcription. In the present work we have studied the influence of crpa specific mutation at the genetic locus of CRP protein on the expression of the deo operon of E. coli. It has been found that the presence of crpa mutation in bacterial genome completely eliminates CytR repression of the deo operon, so that activation of Deo enzymes synthesis by cAMP-CRPa complex becomes possible, even in the presence of CytR. Besides, the modified CRPa protein appears to block the activity of catabolite-sensitive deoPO2 promoter of the deo operon under conditions of cAMP deficiency, which is manifested in the two-fold decrease of deoR derepression in the crpa cells, as compared to the wild type bacteria during the growth on glucose containing medium. It has been supposed that both effects are due to increased affinity of the modified CRPa protein to the specific sites of catabolite sensitive promoters, as compared to the wild type CRP protein.

Escherichia coli↗
PubMed2001

Induction of butane consumption in Pseudomonas butanovora.

The induction of the enzyme activities involved in butane metabolism in Pseudomonas butanovora was characterized. P. butanovora was grown on butane or its metabolites, both singly and in mixtures with other growth substrates. Cells grown in each of the butane metabolites readily consumed the growth substrate and downstream metabolites, but consumed the upstream butane metabolites more slowly. Upstream activities in the butane metabolism could be induced by downstream metabolites, but to much lower levels than with the primary substrate. The induction of butane oxidation was not repressed when P. butanovora was grown or incubated in a mixture of butane and 1-butanol, butyraldehyde or butyrate. However, no induction of butane consumption was observed in a mixture of butane and lactate, which is indicative of catabolite repression. In lactate-grown cells that were rid of the growth substrate and incubated with butane and acetylene (to inactivate newly formed butane monooxygenase), the consumption of butane, 1-butanol and butyraldehyde consumption was not induced. The overall results suggest an independent regulatory mechanism for each of the enzyme activities in butane metabolism. In addition, a low, constitutive butane oxidation was observed in cells grown on substrates other than butane metabolites.

1-Butanol↗
PubMed2000

A positive feedback mechanism controls expression of AlkS, the transcriptional regulator of the Pseudomonas oleovorans alkane degradation pathway.

The AlkS regulator, encoded by the alkS gene of the Pseudomonas oleovorans OCT plasmid, activates the expression of a set of enzymes that allow assimilation of alkanes. We show that the AlkS protein regulates, both negatively and positively, the expression of its own gene. In the absence of alkanes, alkS is expressed from promoter PalkS1, which is recognized by sigmaS-RNA polymerase, and whose activity is very low in the exponential phase of growth and considerably higher in stationary phase. AlkS was found to downregulate this promoter, limiting expression of alkS in stationary phase when alkanes were absent. In the presence of alkanes, AlkS repressed PalkS1 more strongly and simultaneously activated a second promoter for alkS, named PalkS2, located 38 bp downstream from PalkS1. Activation of PalkS2 allowed efficient transcription of alkS when alkanes were present. Transcription from PalkS2 was modulated by catabolite repression when cells were provided with a preferred carbon source. We propose that the expression of alkS is regulated by a positive feedback mechanism, which leads to a rapid increase in alkS transcription when alkanes are present. This mechanism should allow a rapid induction of the pathway, as well as a fast switch-off when alkanes are depleted. An improved model for the regulation of the pathway is proposed.

Alkanes↗
PubMed1975

Regulation of extracellular protease secretion in Pseudomonas maltophilia.

Cells grown in minimal medium and harvested in late exponential phase secreted extracellular protease linearly when suspended at high density in fresh medium. If the cells were suspended with 0.2% (wt/vol) yeast extract and no additional carbon source, the rate of exoenzyme production was increased several-fold. When pyruvate, L-malate, succinate, or alpha-ketoglutarate was added, repression of exoenzyme secretion was observed. The most effective repressor was alpha-ketoglutarate. These compounds were also preferred substrates for growth of Pseudomonas maltophilia. The data suggest that exoenzyme secretion is controlled by a mechanism similar to catabolite repression. In support of this was the observation that alpha-ketoglutarate repressed exoenzyme secretion preferentially with respect to total protein synthesis. The addition of inhibitors that affect protein synthesis indicated that exoenzyme secretion is several times more sensitive than is total protein synthesis. The addition of chloramphenicol and rifamycin-SV to actively secreting cell suspensions suggested that de novo protein synthesis is required, but that exoenzyme secretion may be supported for at least 30 min in the absence of messenger synthesis. Rifamycin-insensitive protease secretion could be reversed by either alpha-ketoglutarate or chloramphenicol, suggesting that alpha-ketoglutarate is coupled to a post-transcriptional control mechanism.

Alanine↗
PubMed1982

Derepression of an NAD-linked dehydrogenase that serves an Escherichia coli mutant for growth on glycerol.

An Escherichia coli mutant using an NAD-linked dehydrogenase instead of an ATP-dependent kinase as the first enzyme for glycerol dissimilation excreted dihydroxyacetone during the initial phase of growth. The intermediate was salvaged as growth of the culture advanced. The transient loss of the intermediate into the medium appeared to be partly determined by variation of the level of glycerol dehydrogenase with growth conditions. With up to 2% casein hydrolysate as the carbon and energy source, the cellular level of the dehydrogenase increased 1 order of magnitude at the end of growth. This increase was probably caused by the depletion of certain metabolites and was prevented by the addition of pyruvate or glucose to the growth medium. The repressive effect of these compounds was not lifted by the addition of cyclic AMP. Diminution of oxygen tension in the culture medium with increased cell density was not directly responsible for the increase of the enzyme level. Thus, neither catabolite repression nor respiratory repression was implicated as an important control mechanism in the synthesis of this enzyme. Since increases in the specific activity of the enzyme in cell extracts reflected increases in the concentration of the enzyme protein, post-translational control was also not involved. A novel kind of regulation of gene expression is indicated.

Bacterial Proteins↗
PubMed1969

Repression by glucose of acetohydroxy acid synthetase in Escherichia coli B.

Acetolactate formation in Escherichia coli B results from the activity of a single system, acetohydroxy acid synthetase, which has a pH optimum of 8.0 and is sensitive to end-product inhibition by l-valine. Acetohydroxy acid synthetase was found to be subject to catabolite repression, and the nature and concentration of the carbon source had a greater effect on the formation of the enzyme than had the known end products (valine, isoleucine, leucine and pantothenate) of the biosynthetic pathways of which this enzyme is a member. The results suggest that acetohydroxy acid synthetase may play an amphibolic role in E. coli B.

Enzyme Repression↗
PubMed1982

Repression of penicillin G acylase of Proteus rettgeri by tricarboxylic acid cycle intermediates.

The regulation of the penicillin acylase in proteus rettgeri ATCC 31052 was compared with that of the enzyme in Escherichia coli ATCC 9637. Unlike the E. coli acylase, the P. rettgeri enzyme was not induced by phenylacetic acid, nor was it subject to catabolite repression by glucose. The P. rettgeri acylase appears to be expressed constitutively but is subject to repression by the C4-dicarboxylic acids of the tricarboxylic acid cycle, succinate, fumarate, and malate.

Amidohydrolases↗
PubMed1995

Starvation stress modulates the expression of the Aspergillus nidulans brlA regulatory gene.

Expression of the Aspergillus nidulans brlA gene plays a fundamental role in the switch from vegetative growth to asexual reproduction. Using a media-shifting protocol to induce submerged sporulation and brlA-lacZ as an expression marker, it was shown that carbon and nitrogen starvation stress induced brlA transcription to different degrees. Glucose starvation induced briA rapidly to high levels and resulted in spore formation on reduced conidiophores, whereas nitrogen starvation induced brlA gradually to lower levels and sporulation occurred to a lesser extent but from more complex conidiophores. beta-Galactosidase activity paralleled brlA alpha and brlA beta mRNA. No clear qualitative differences between the two brlA transcripts were found in these starvation conditions, suggesting that the different patterns of sporulation could be explained by quantitative expression differences. Since brlA mRNA did not accumulate in the presence of a high glucose concentration, we investigated the role of other carbon sources on brlA expression. Non-repressing carbon sources such as glycerol, acetate and arabinose were as effective as glucose in preventing brlA mRNA accumulation, suggesting that the glucose effects on brlA expression could be explained as a response to nutrient starvation, rather than by carbon catabolite repression. Despite similar low levels of brlA transcripts being detected during growth in glucose or non-repressing carbon sources, conidiophores were formed only in medium containing glycerol, acetate or arabinose. When mycelia were not shifted to starvation conditions, sporulation was not observed in standard minimal medium even after glucose was exhausted, unless the medium was buffered.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspergillus nidulans↗
PubMed1997

UBI4, the polyubiquitin gene of Saccharomyces cerevisiae, is a heat shock gene that is also subject to catabolite derepression control.

Carbon and nitrogen regulation of UBI4, the stress-inducible polyubiquitin gene of Saccharomyces cerevisiae, was investigated using a UBI4 promoter-LacZ fusion gene (UBI4-LacZ). Expression of this gene in cells grown on different media indicated that the UBI4 promoter is more active during growth on respiratory than on fermentable carbon sources but is not subject to appreciable control by nitrogen catabolite repression. UBI4-LacZ expression was virtually identical in cells having constitutively high (ras2, sra1-13) or constitutively low (ras2) levels of cyclic AMP-dependent protein kinase activity, indicating that this kinase does not exert a major influence on UBI4 expression. Catabolite derepression control of the UBI4 promoter was confirmed by measurements of UBI4-LacZ expression in hap mutant and wild-type strains before and after transfer from glucose to lactate. Mutagenesis of the perfect consensus for HAP2/3/4 complex binding at position -542 resulted in considerable reduction of UBI4 promoter derepression with respiratory adaptation in HAP wild-type cells and abolished the reduced UBI4-LacZ derepression normally seen when aerobic cultures of the hap1 mutant are transferred from glucose to lactate. This HAP2/3/4 binding site is therefore a major element contributing to catabolite derepression of the UBI4 promoter, although data obtained with hapl mutant cells indicated that HAP1 also contributes to this derepression. The HAP2/3/4 and HAP1 systems are normally found to activate genes for mitochondrial (respiratory) functions. Their involvement in mediating higher activity of the UBI4 promoter during respiratory growth may reflect the contribution of UBI4 expression to tolerance of oxidative stress.

Biopolymers↗
PubMed1991

Saccharomyces cerevisiae null mutants in glucose phosphorylation: metabolism and invertase expression.

A congenic series of Saccharomyces cerevisiae strains has been constructed which carry, in all combinations, null mutations in the three genes for glucose phosphorylation: HXK1, HXK2 and GLK1, coding hexokinase 1 (also called PI or A), hexokinase 2 (PII or B), and glucokinase, respectively: i.e., eight strains, all of which grow on glucose except for the triple mutant. All or several of the strains were characterized in their steady state batch growth with 0.2% or 2% glucose, in aerobic as well as respiration-inhibited conditions, with respect to growth rate, yield, and ethanol formation. Glucose flux values were generally similar for different strains and conditions, provided they contained either hexokinase 1 or hexokinase 2. And their aerobic growth, as known for wild type, was largely fermentative with ca. 1.5 mol ethanol made per mol glucose used. The strain lacking both hexokinases and containing glucokinase was an exception in having reduced flux, a result fitting with its maximal rate of glucose phosphorylation in vitro. Aerobic growth of even the latter strain was largely fermentative (ca. 1 mol ethanol per mol glucose). Invertase expression was determined for a variety of media. All strains with HXK2 showed repression in growth on glucose and the others did not. Derepression in the wild-type strain occurred at ca. 1 mM glucose. The metabolic data do not support- or disprove-a model with HXK2 having only a secondary role in catabolite repression related to more rapid metabolism.

Gene Expression Regulation, Fungal↗
PubMed1990

In vivo cloning and characterization of the gabCTDP gene cluster of Escherichia coli K-12.

The gabCTDP gene cluster, which specifies and regulates synthesis of the gamma-aminobutyrate (GABA) transport carrier, of glutamate-succinic semialdehyde transaminase, and of succinic semialdehyde dehydrogenase, responsible for the uptake and metabolism of gamma-aminobutyric acid in Escherichia coli K-12, was cloned in vivo, using the mini-Mu replicon bacteriophage Mu dI5086 as the vector. A subclone containing a 7.8-kilobase (kb) EcoRI-HindIII fragment complemented all of our Gab- mutants. By restriction mapping, this DNA fragment was located at kb 2800.5 to 2808.5 on the physical map of the E. coli K-12 chromosome. A subclone containing a 1.8-kb EcoRI-SalI fragment complemented the gab-repressed strain CS101A (wild-type gabC) but did not complement any gab structural gene mutants. The gab genes are divergently transcribed from promoters located in the vicinity of the unique BamHI site. Transcription in both directions is under dual control of catabolite repression and nitrogen regulation. Using a procaryotic DNA-directed translation system, we observed three insert-coded polypeptide bands of 53 to 55, 45 to 48, and 40 to 43 kilodaltons (kDa). In vivo studies with subcloned fragments of the gab DNA identified the 53- to 55- and 45- to 48-kDa bands as products of the BamHI-SalI fragment and the 40- to 43-kDa band as the product of the EcoRI-SalI fragment. An additional 26- to 28-kDa band was identified as the product of the BamHI-HindIII fragment. Furthermore, the BamHI-SalI fragment was shown to specify synthesis of the two GABA enzymes, whereas synthesis of the GABA carrier was specified by the BamHI-HindIII fragment. No catalytic function in addition to its regulatory role could be attributed to the EcoRI-SalI gene product.

Aldehyde Oxidoreductases↗