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 271 records · Page 15Linked to original sources
PubMed2002

Cytoplasmic compartmentation of Gln3 during nitrogen catabolite repression and the mechanism of its nuclear localization during carbon starvation in Saccharomyces cerevisiae.

Regulated intracellular localization of Gln3, the transcriptional activator responsible for nitrogen catabolite repression (NCR)-sensitive transcription, permits Saccharomyces cerevisiae to utilize good nitrogen sources (e.g. glutamine and ammonia) in preference to poor ones (e.g. proline). During nitrogen starvation or growth in medium containing a poor nitrogen source, Gln3 is nuclear and NCR-sensitive transcription is high. However, when cells are grown in excess nitrogen, Gln3 is localized to the cytoplasm with a concomitant decrease in gene expression. Treating cells with the Tor protein inhibitor, rapamycin, mimics nitrogen starvation. Recently, carbon starvation has been reported to cause nuclear localization of Gln3 and increased NCR-sensitive transcription. Here we show that nuclear localization of Gln3 during carbon starvation derives from its indirect effects on nitrogen metabolism, i.e. Gln3 does not move into the nucleus of carbon-starved cells if glutamine rather than ammonia is provided as the nitrogen source. In addition, these studies have clearly shown Gln3 is not uniformly distributed in the cytoplasm, but rather localizes to punctate or tubular structures. Analysis of these images by deconvolution microscopy suggests that Gln3 is concentrated in or associated with a highly structured system in the cytosol, one that is possibly vesicular in nature. This finding may impact significantly on how we view (i) the mechanism by which Tor regulates the intracellular localization of Gln3 and (ii) how proteins move into and out of the nucleus.

Carbon↗
PubMed2003

Engineering of carbon catabolite repression in recombinant xylose fermenting Saccharomyces cerevisiae.

Two xylose-fermenting glucose-derepressed Saccharomyces cerevisiae strains were constructed in order to investigate the influence of carbon catabolite repression on xylose metabolism. S. cerevisiae CPB.CR2 (Delta mig1, XYL1, XYL2, XKS1) and CPB.MBH2 (Delta mig1, Delta mig2, XYL1, XYL2, XKS1) were analysed for changes in xylose consumption rate and ethanol production rate during anaerobic batch and chemostat cultivations on a mixture of 20 g l(-1) glucose and 50 g l(-1) xylose, and their characteristics were compared to the parental strain S. cerevisiae TMB3001 ( XYL1, XYL2, XKS1). Improvement of xylose utilisation was limited during batch cultivations for the constructed strains compared to the parental strain. However, a 25% and 12% increased xylose consumption rate during chemostat cultivation was achieved for CPB.CR2 and CPB.MBH2, respectively. Furthermore, during chemostat cultivations of CPB.CR2, where the cells are assumed to grow under non-repressive conditions as they sense almost no glucose, invertase activity was lower during growth on xylose and glucose than on glucose only. The 3-fold reduction in invertase activity could only be attributed to the presence of xylose, suggesting that xylose is a repressive sugar for S. cerevisiae.

Anaerobiosis↗
PubMed2005

Structure theorems and the dynamics of nitrogen catabolite repression in yeast.

By using current biological understanding, a conceptually simple, but mathematically complex, model is proposed for the dynamics of the gene circuit responsible for regulating nitrogen catabolite repression (NCR) in yeast. A variety of mathematical "structure" theorems are described that allow one to determine the asymptotic dynamics of complicated systems under very weak hypotheses. It is shown that these theorems apply to several subcircuits of the full NCR circuit, most importantly to the URE2-GLN3 subcircuit that is independent of the other constituents but governs the switching behavior of the full NCR circuit under changes in nitrogen source. Under hypotheses that are fully consistent with biological data, it is proven that the dynamics of this subcircuit is simple periodic behavior in synchrony with the cell cycle. Although the current mathematical structure theorems do not apply to the full NCR circuit, extensive simulations suggest that the dynamics is constrained in much the same way as that of the URE2-GLN3 subcircuit. This finding leads to the proposal that mathematicians study genetic circuits to find new geometries for which structure theorems may exist.

Glutathione Peroxidase↗
PubMed1980

Catabolite repression of enzyme synthesis does not prevent sporulation.

In the presence of excess glucose, a decrease of guanine nucleotides in Bacillus subtilis initiated sporulation but did not prevent catabolite repression of three enzymes. Therefore, the ultimate mechanism(s) repressing enzyme synthesis differs from that suppressing sporulation.

Acetoin Dehydrogenase↗
PubMed1991

Cloning of a catabolite repression control (crc) gene from Pseudomonas aeruginosa, expression of the gene in Escherichia coli, and identification of the gene product in Pseudomonas aeruginosa.

Mutants which are defective in catabolite repression control (CRC) of multiple independently regulated catabolic pathways have been previously described. The mutations were mapped at 11 min on the Pseudomonas aeruginosa chromosome and designated crc. This report describes the cloning of a gene which restores normal CRC to these Crc- mutants in trans. The gene expressing this CRC activity was subcloned on a 2-kb piece of DNA. When this 2-kb fragment was placed in a plasmid behind a phage T7 promoter and transcribed by T7 RNA polymerase, a soluble protein with a molecular weight (MW) of about 30,000 was produced in Escherichia coli. A soluble protein of identical size was overproduced in a Crc- mutant when it contained the 2-kb fragment on a multicopy plasmid. This protein could not be detected in the mutant containing the vector without the 2-kb insert or with no plasmid. When a 0.3-kb AccI fragment was removed from the crc gene and replaced with a kanamycin resistance cassette, the interrupted crc gene no longer restored CRC to the mutant, and the mutant containing the interrupted gene no longer overproduced the 30,000-MW protein. Pools of intracellular cyclic AMP and the activities of adenylate cyclase and phosphodiesterase were measured in mutant and wild-type strains with and without a plasmid containing the crc gene. No consistent differences between any strains were found in any case. These results provide original evidence for a 30,000-MW protein encoded by crc+ that is required for wild-type CRC in P. aeruginosa and confirms earlier reports that the mode of CRC is cyclic AMP independent in this bacterium.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1992

Nitrogen catabolite repression of arginase (CAR1) expression in Saccharomyces cerevisiae is derived from regulated inducer exclusion.

Expression of the Saccharomyces cerevisiae arginase (CAR1) gene is regulated by induction and nitrogen catabolite repression (NCR). Arginine was demonstrated to be the native inducer. CAR1 sensitivity to NCR has long been accepted to be accomplished through a negative control mechanism, and cis-acting sites for it have been hypothesized. In search of this negatively acting site, we discovered that CAR1 sensitivity to NCR derives from regulated inducer (arginine) exclusion. The route of catabolic entry of arginine into the cell, the general amino acid permease (GAP1), is sensitive to NCR. However, CAR1 expression in the presence of sufficient intracellular arginine is NCR insensitive.

Arginase↗
PubMed2005

Pleiotropic effect of the SCO2127 gene on the glucose uptake, glucose kinase activity and carbon catabolite repression in Streptomyces peucetius var. caesius.

SCO2127 and SCO2126 (glkA) are adjacent regions located in Streptomyces coelicolor DNA. glkA encodes glucose kinase (Glk), which has been implicated in carbon catabolite repression (CCR) in the genus Streptomyces. In this work, the glkA and SCO2127 genes from S. coelicolor were used, either individually or together, to transform three mutants of Streptomyces peucetius var. caesius resistant to CCR. These mutants present decreased levels of Glk, and deficiency in glucose transport. When the mutants were transformed with a plasmid containing the SCO2127 sequence, glucose uptake and Glk activity values were increased to levels similar to or higher than those of the original strain, and each strain regained sensitivity to CCR. This result was surprising considering that the putative SCO2127 amino acid sequence does not seem to encode a glucose permease or a Glk. In agreement with these results, an increase in glkA mRNA levels was observed in a CCR-resistant mutant transformed with SCO2127 compared with those of the original strain and the CCR-resistant mutant itself. As expected, recombinants containing the glkA sequence reverted Glk to normal activity values, but glucose uptake remained deficient. The data suggest that the SCO2127 gene product enhances transcription of both genes, and support the first specific role for this region in Streptomyces species. The physiological consequence of this effect is an increase in the glucose catabolites that may be involved in eliciting CCR in this genus.

Antimetabolites↗
PubMed2003

Distinct molecular mechanisms involved in carbon catabolite repression of the arabinose regulon in Bacillus subtilis.

The Bacillus subtilis proteins involved in the utilization of L-arabinose are encoded by the araABDLMNPQ-abfA metabolic operon and by the araE/araR divergent unit. Transcription from the ara operon, araE transport gene and araR regulatory gene is induced by L-arabinose and negatively controlled by AraR. Additionally, expression of both the ara operon and the araE gene is regulated at the transcriptional level by glucose repression. Here, by transcriptional fusion analysis in different mutant backgrounds, it is shown that CcpA most probably complexed with HPr-Ser46-P plays the major role in carbon catabolite repression of the ara regulon by glucose and glycerol. Site-directed mutagenesis and deletion analysis indicate that two catabolite responsive elements (cres) present in the ara operon (cre araA and cre araB) and one cre in the araE gene (cre araE) are implicated in this mechanism. Furthermore, cre araA located between the promoter region of the ara operon and the araA gene, and cre araB placed 2 kb downstream within the araB gene are independently functional and both contribute to glucose repression. In Northern blot analysis, in the presence of glucose, a CcpA-dependent transcript consistent with a message stopping at cre araB was detected, suggesting that transcription 'roadblocking' of RNA polymerase elongation is the most likely mechanism operating in this system. Glucose exerts an additional repression of the ara regulon, which requires a functional araR.

Arabinose↗
PubMed2000

Nitrogen catabolite repression of DAL80 expression depends on the relative levels of Gat1p and Ure2p production in Saccharomyces cerevisiae.

GATA family activators (Gln3p and Gat1p) and repressors (Dal80p and Deh1p) regulate nitrogen catabolite repression (NCR)-sensitive transcription in Saccharomyces cerevisiae presumably via their competitive binding to the GATA sequences upstream of NCR-sensitive genes. Ure2p, which is not a GATA family member, inhibits Gln3p/Gat1p from functioning in the presence of good nitrogen sources. We show that NCR-sensitive DAL80 transcription can be influenced by the relative levels of GAT1 and URE2 expression. NCR, normally observed with ammonia or glutamine, is severely diminished when Gat1p is overproduced, and this inhibition is overcome by simultaneously increasing URE2 expression. Further, overproduction of Ure2p nearly eliminates NCR-sensitive transcription under derepressive growth conditions, i.e. with proline as the sole nitrogen source. Enhanced green fluorescent protein-Gat1p is nuclear when Gat1p-dependent transcription is high and cytoplasmic when it is inhibited by overproduction of Ure2p.

Base Sequence↗
PubMed1999

Carbon catabolite repression of the Aspergillus nidulans xlnA gene.

Expression of the Aspergillus nidulans 22 kDa endoxylanase gene, xlnA, is controlled by at least three mechanisms: specific induction by xylan or xylose; carbon catabolite repression (CCR); and regulation by ambient pH. Deletion analysis of xlnA upstream sequences has identified two positively acting regions: one that mediates specific induction by xylose; and another that mediates the influence of ambient pH and contains two PacC consensus binding sites. The extreme derepressed mutation creAd30 results in considerable, although not total, loss of xlnA glucose repressibility, indicating a major role for CreA in its CCR. Three consensus CreA binding sites are present upstream of the structural gene. Point mutational analysis using reporter constructs has identified a single site, xlnA.C1, that is responsible for direct CreA repression in vivo. Using the creAd30 derepressed mutant background, our results indicate the existence of indirect repression by CreA.

Aspergillus nidulans↗
PubMed2000

Constitutive biosynthesis and localization of alcohol oxidase in the ethanol-insensitive catabolite repression mutant ecr1 of the yeast Pichia methanolica.

The activity and localization of alcohol oxidase (EC 1.1.3.13) have been studied in the Pichia methanolica mutant ecr1 defective in ethanol-induced catabolite repression of enzymes of methanol utilization. Ultrasctuctural, immunocytochemical, and biochemical analyses revealed the presence of peroxisomes containing active alcohol oxidase in the mutant grown in media with methanol, ethanol, and a mixture of both substrates. No alcohol oxidase was detected in the wild-type cells (ECR1) grown on ethanol-containing media. Mutant ecr1 growing in medium containing a mixture of different alcohols and the wild-type strain growing on methanol demonstrated similar buoyant density of peroxisomes (1.24-1.27 g/cm3)during isopicnic centrifugation of the organelles in sucrose density gradients. The integrated genetic, immunocytochemical, and biochemical data are in agreement with the model that synthesis, translocation into peroxisomes, and assembly of alcohol oxidase in P. methanolica may not require any regulatory signals induced by methanol.

Alcohol Oxidoreductases↗
PubMed2000

Saccharomyces cerevisiae GATA sequences function as TATA elements during nitrogen catabolite repression and when Gln3p is excluded from the nucleus by overproduction of Ure2p.

Saccharomyces cerevisiae selectively uses good nitrogen sources (glutamine) in preference to poor ones (proline) by repressing GATA factor-dependent transcription of the genes needed to transport and catabolize poor nitrogen sources, a physiological process designated nitrogen catabolite repression (NCR). We show that some NCR-sensitive genes (CAN1, DAL5, DUR1,2, and DUR3) produce two transcripts of slightly different sizes. Synthesis of the shorter transcript is NCR-sensitive and that of the longer transcript is not. The longer transcript also predominates in gln3Delta mutants irrespective of the nitrogen source provided. We demonstrate that the longer mRNA species arises through the use of an alternative transcription start site generated by Gln3p-binding sites (GATAAs) being able to act as surrogate TATA elements. The ability of GATAAs to serve as surrogate TATAs, i.e. when synthesis of the shorter, NCR-sensitive transcripts are inhibited, correlates with sequestration of enhanced green fluorescent protein (EGFP)-Gln3p in the cytoplasm in a way that is indistinguishable from that seen with EGFP-Ure2p. However, when the shorter, NCR-sensitive DAL5 transcript predominates, EGFP-Gln3p is nuclear. These data suggest that the mechanism underlying NCR involves the cytoplasmic association of Ure2p with Gln3p, an interaction that prevents Gln3p from reaching it is binding sites upstream of NCR-sensitive genes.

Amino Acid Transport Systems↗
PubMed1983

Cyclic AMP may not be involved in catabolite repression in Saccharomyces cerevisiae: evidence from mutants unable to synthesize it.

Yeast cells with a nonsense adenylate cyclase mutation, cyr1-3, required cyclic AMP for growth. This phenotype was suppressed by the byc1 mutation; however, cyr1-3 bcy1 cells produced no detectable level of adenylate cyclase or cyclic AMP. On induction, the bcy1 and cyr1-3 bcy1 mutant cells produced the same levels of galactokinase and alpha-D-glucosidase as did the wild-type cells and fourfold-higher levels of invertase. Since galactokinase synthesis was severely repressed by glucose in the constitutive GAL81 mutants, irrespective of the cyr1-3 bcy1 genotype, cyclic AMP may not be involved in catabolite repression.

Adenylyl Cyclases↗
PubMed2002

Multiple operons connected with catabolism of aromatic compounds in Acinetobacter sp. strain ADP1 are under carbon catabolite repression.

Repression of enzymes contributing to degradation of aromatic compounds via the beta-ketoadipate pathway in the presence of additional carbon sources (carbon catabolite repression) in the bacterium Acinetobacter sp. strain ADP1 is described. The phenomenon was investigated on the level of specific activity of protocatechuate 3,4-dioxygenase and p-hydroxybenzoate hydroxylase participating in catabolism of protocatechuate and p-hydroxybenzoate. Strong repression (90%) was found in cells grown on succinate and acetate in addition to the aromatic carbon source; partial derepression occurred towards the end of the logarithmic growth phase. Glucose, pyruvate, or lactate as secondary carbon sources had no repressing effect. The consumption of the aromatic substrate from the medium was delayed in the presence of acetate and succinate. The differences in specific enzyme activities were reflected at the transcript level for three operons connected to catabolism of aromatic compounds (pob, pca, van) as shown by Northern blot hybridization. Transcriptional fusions between the promoters of the pob and the pca operon identified the transcriptional level as the regulatory one. A mechanism of global regulation is postulated, which enables the organism to consume the offered carbon sources hierarchically in the most efficient manner.

Acinetobacter↗
PubMed1991

Sequences of two adjacent genes, one (DAL2) encoding allantoicase and another (DCG1) sensitive to nitrogen-catabolite repression in Saccharomyces cerevisiae.

Reported are the nucleotide sequences of the yeast allantoicase-encoding gene (DAL2) and that of an unknown gene adjacent to it. Expression of the unidentified gene is sensitive to nitrogen catabolite repression (NCR) and regulated by the DAL80 product, a previously documented control element regulating allantoin pathway gene expression. Both genes possess multiple upstream activation sequences (UAS) homologous to the UASNTR element shown to be required for sensitivity to NCR. Also present upstream from DAL2 is a mutant form of the upstream induction sequence required for response of DAL7 to induction. Its occurrence in mutant form is consistent with the poor induction of DAL2 expression observed in vivo.

Allantoin↗