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PubMed1982

Catabolite repression in Streptomyces venezuelae. Induction of beta-galactosidase, chloramphenicol production, and intracellular cyclic adenosine 3',5'-monophosphate concentrations.

Chloramphenicol production was studied in cultures of Streptomyces venezuelae growing in a simple buffered medium with ammonia as the nitrogen source and glucose, lactose, or a glucose-lactose mixture as the sole source of carbon. With each carbon source the antibiotic was formed during growth. In the glucose-lactose medium, the production pattern was biphasic; a marked decrease in the rate of synthesis was associated with depletion of glucose from the medium and a corresponding diauxie pause in growth. Cells of S. venezuelae contained an inducible beta-galactosidase. Induction by lactose was suppressed by glucose. Measurement of the concentration of intracellular adenosine 3',5'-cyclic monophosphate during growth of cultures with glucose or a glucose-lactose mixture as the source of carbon showed no appreciable changes coinciding with depletion of glucose or the onset of chloramphenicol biosynthesis. It is concluded that the cyclic nucleotide does not mediate selective nutrient utilization or control antibiotic biosynthesis in this organism.

Chloramphenicol↗
PubMed2004

Real-time PCR analysis of carbon catabolite repression of cellobiose dehydrogenase gene transcription in Trametes versicolor.

Cellobiose dehydrogenase production in Trametes versicolor is repressed when additional carbon sources, such as glucose, maltose, galactose, arabinose, and xylose, are added to the fungal cultures growing on cellulose. Real-time quantitative reverse transcription-polymerase chain reaction has been used to demonstrate that the addition of galactose, arabinose, and xylose results in 19-, 92-, and 114-fold reductions, respectively, in cdh transcript levels 96 h post-addition. Glucose exhibits the greatest repressive effect, resulting in a 3400-fold decrease in cdh transcript levels.

Arabinose↗
PubMed1996

Sequence-specific binding sites in the Taka-amylase A G2 promoter for the CreA repressor mediating carbon catabolite repression.

The N-terminal part of the CreA protein encompassing two zinc fingers was expressed in Escherichia coli as a fusion protein with the maltose binding protein (MalE) of E. coli. Our results show that CreA binds to the promoter of the Taa-G2 gene encoding Taka-amylase A of Aspergillus oryzae. DNase I footprinting experiments showed that CreA bound to three sites with high affinity and to one site with low affinity within the first 401-bp region upstream of the transcription initiation site. All of the sites contained sequences related to the CreA consensus binding site (5'-SYGGRG-3'), and are suggested to participate in repression of the Taa-G2 gene in response to glucose.

Amino Acid Sequence↗
PubMed1984

Carbon catabolite repression of penicillin biosynthesis by Penicillium chrysogenum.

The addition of glucose to batch cultures of Penicillium chrysogenum AS-P-78 reduced the biosynthesis of penicillin. This regulatory effect was also observed in penicillin biosynthesis by nitrogen-limited resting cells when cultures were previously grown in high concentrations of glucose. The effect of glucose was concentration-dependent in the range of 28-140 mM. Incorporation of L-[U-14C]valine into penicillin in nitrogen-limited resting cultures was reduced by 70% when cells were grown on 140 mM glucose, as compared with that grown on lactose. It was not affected when the sugar was added to the resting cell system, in which penicillin biosynthesis took place without growth. Fructose, galactose and sucrose exerted the regulatory effect to the same extent as glucose (64 to 70%). Lactose did not exert suppression of penicillin biosynthesis. Penicillin-synthesizing activity in control cultures with lactose reached a peak at 24 hours of incubation and decreased slowly thereafter, as studied with resting cell cultures in which further protein synthesis was blocked with cycloheximide. Glucose repressed the formation of penicillin-synthesizing enzymes, but had no effect on the activity of these enzymes. These results suggest that glucose represses but does not inhibit penicillin biosynthesis.

Glucose↗
PubMed2003

[Effect of the pho85 mutation on the catabolite repression of the CIT1 gene in yeasts Saccharomyces cerevisiae].

The Krebs cycle is one of the major metabolic pathways in a cell, which includes both catabolic and anabolic reactions. The first enzyme of the Krebs cycle, citrate synthase, catalyzes one of a few irreversible reactions of the cycle, citrate formation from acetyl-CoA and oxaloacetate. Expression of the CIT1 gene encoding the mitochondrial form of this enzyme in Saccharomyces cerevisiae is repressed on glucose- and glutamate-containing medium and activated on the raffinose-containing medium. In this work, the dependence of glucose repression of the CIT1 gene on the content of phosphate in the medium was studied. On the phosphate-deficient medium, the level of the CIT1 gene expression was increased twice. A low-molecular-weight (about 34 kDa) protein was identified and shown to interact with a region of the CIT1 gene promoter (from -367 to -346 bp), which controls the glucose repression. The results obtained suggest that the Pho4 protein is involved in regulation of the CIT1 gene expression on the glucose-containing and phosphate-deficient medium. Disruption of the PHO85 gene encoding phosphoprotein kinase (Pho4p is the substrate of this enzyme) leads to alleviation of glucose repression of the CIT1 gene. Thus, in yeast cells grown in the presence of glucose, the PHO85 gene mediates downregulation of the CIT1 expression.

Citrate (si)-Synthase↗
PubMed1986

Steady state analysis of mitochondrial RNA after growth of yeast Saccharomyces cerevisiae under catabolite repression and derepression.

The steady state levels of mitochondrial rRNAs, 5 tRNAs, the 9 S RNA, and the RNA products from the genes coding for subunits 6 and 9 of the ATP synthase, cytochrome b, and subunit 1 of cytochrome oxidase have been determined after growth of yeast under conditions of respiratory repression or derepression. The analysis indicates that the mitochondrial rRNAs are present in 2000 or 9000 copies/cell in repressed or derepressed yeast, respectively. The levels of the other RNAs also differed to a similar extent, with the exception of the level of the tRNAfMet which differs by only 1.7-fold. The levels of the individual protein coding RNAs varied from 480 copies/cell for the Oli-1 RNA to 100 copies/cell for the Oli-2 RNA under derepressive conditions and from 130 copies/cell to 33 copies/cell for the same RNAs in glucose repressive conditions. The levels of the tRNAs varied even more markedly, ranging from 4200 copies/cell for the tRNAPhe to 240 copies/cell for the tRNACys after growth in derepressive conditions and from 800 copies/cell for the tRNAfMet to 30 copies/cell for the tRNACys of glucose repressed yeast. These results indicate that glucose repression uniformly decreases the levels of the individual mitochondrial RNAs studied. This decrease is related to a lower synthesis of mitochondrial RNA in the glucose repressed cells as compared to derepressed cells.

Genes, Fungal↗
PubMed1978

Haemoprotein formation in yeast. III. The role of carbon catabolite repression in the regulation of catalase A and T formation.

Catalase A and T activities were investigated in two standard strains and three catalase regulatory cgr mutants of yeast in respiratory competent and incompetent states, which were under various degrees of glucose repression. The formation of catalase A was very sensitive to glucose repression and was characterized by a long delay in derepression. Deprivation of the energy source in respiratory incompetent cells prevented the derepression of catalase A. The lack of catalase A in respiratory imcompetent cells can be overcome by growing the cells in raffinose or by the prolongation of the fermentative phase of derepression. Catalase T is under control of different regulatory systems probably common with some other haemoproteins.

Catalase↗