Showing papers on "Catabolite repression published in 1971"

Adenosine 3′:5′-Cyclic Monophosphate Concentration in the Bacterial Host Regulates the Viral Decision between Lysogeny and Lysis

Abstract: Mutants of Salmonella typhimurium defective in adenylate cyclase (cya gene) or in cAMP receptor protein (crp gene) are lysogenized at reduced frequency by phage P22. One class of the bacterial mutants with an altered RNA polymerase (rif gene) is also lysogenized at reduced frequency. In the three types of mutant bacteria, the phage's decision between lysogeny and lysis is shifted to lysis and the phage form clear plaques. We propose that in wild-type bacteria the cAMP-receptor protein, in combination with cAMP, activates bacterial RNA polymerase to transcribe certain phage genes that are required for efficient lysogenization. Under conditions of strong catabolite repression, when the supply of energy and biosynthetic components is abundant and the concentration of cAMP is low, the phage would multiply and lyse the cell. When the supply of energy is deficient and the concentration of cAMP is high, the phage would lysogenize the cell. Phage mutants have been isolated that form turbid plaques on the three classes of bacterial mutants due to a higher frequency of lysogeny. These phage mutants have been shown by complementation to be defective in the same gene, which we have called the cly gene. These cly mutants lysogenize the wild-type bacteria with a 99% frequency and, thus, do not form plaques on them. Other kinds of bacterial mutants are also lysogenized at reduced frequency by phage P22. They may be altered in other physiological control systems that influence the frequency of lysogenization.

Purification and DNA-Binding Properties of the Catabolite Gene Activator Protein

Abstract: A protein required for the activation of the lac operon has been extensively purified and partly characterized. This protein, called CGA protein (catabolite gene activator protein, sometimes named CAP), is a dimer with subunits of 22,000 daltons. Purified CGA protein has a substantial affinity for DNA; this affinity is greatly strengthened by cAMP and strongly inhibited by cGMP. Other studies have shown that these cyclic nucleotides compete for a binding site on CGA protein. The opposing effects of the two cyclic compounds in DNA-CGA protein binding show a parallel behavior to their effects on the expression of the lac operon. Thus cAMP, in addition to CGA protein, is required for expression of the lac operon, whereas cGMP inhibits the expression. The obvious inference is that CGA protein activates the lac operon by binding to the DNA under the influence of cAMP. Thus, CGA protein seems to be a new type of regulatory protein: a DNA-binding activator.

Catabolite Repression of Tryptophanase in Escherichia coli

Abstract: Catabolite repression of tryptophanase was studied in detail under various conditions in several strains of Escherichia coli and was compared with catabolite repression of β-glactosidase. Induction of tryptophanase and β-galactosidase in cultures grown with various carbon sources including succinate, glycerol, pyruvate, glucose, gluconate, and arabinose is affected differently by the various carbon sources. The extent of induction does not seem to be related to the growth rate of the culture permitted by the carbon source during the course of the experiment. In cultures grown with glycerol as carbon source, preinduced for β-galactosidase or tryptophanase and made permeable by ethylenediaminetetraacetic acid (EDTA) treatment, catabolite repression of tryptophanase was not affected markedly by the addition of cAMP (3′,5′-cyclic adenosine monophosphate). Catabolite repression by glucose was only partially relieved by the addition of cAMP. In contrast, under the same conditions, cAMP completely relieved catabolite repression of β-galactosidase by either pyruvate or glucose. Under conditions of limited oxygen, induction of tryptophanase is sensitive to catabolite repression; under the same conditions, β-galactosidase induction is not sensitive to catabolite repression. Induction of tryptophanase in cells grown with succinate as carbon source is sensitive to catabolite repression by glycerol and pyruvate as well as by glucose. Studies with a glycerol kinaseless mutant indicate that glycerol must be metabolized before it can cause catabolite repression. The EDTA treatment used to make the cells permeable to cAMP was found to affect subsequent growth and induction of either β-galactosidase or tryptophanase much more adversely in E. coli strain BB than in E. coli strain K-12. Inducation of tryptophanase was reduced by the EDTA treatment significantly more than induction of β-galactosidase in both strains. Addition of 2.5 × 10−3m cAMP appeared partially to reverse the inhibitory effect of the EDTA treatment on enzyme induction but did not restore normal growth.

Overproduction of microbial metabolites and enzymes due to alteration of regulation

Abstract: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . l 13 1. Coordination of Microbial Metabolism . . . . . . . . . . . . . . . 114 a) Induction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 b) Catabolite Regulation . . . . . . . . . . . . . . . . . . . . . . . 116 c) Feedback Regulation . . . . . . . . . . . . . . . . . . . . . . . 117 d) Branched Pathways . . . . . . . . . . . . . . . . . . . . . . . . 118 2. Overproduction of Metabolites . . . . . . . . . . . . . . . . . . . 119 a) Primary Metabolites . . . . . . . . . . . . . . . . . . . . . . . 119 b) Secondary Metabolites . . . . . . . . . . . . . . . . . . . . . . 125 3. Overproduction of Enzymes . . . . . . . . . . . . . . . . . . . . 130 a) Addition of Inducers . . . . . . . . . . . . . . . . . . . . . . . 132 b) Decrease in Concentration of Repressors . . . . . . . . . . . . . . 132 c) Mutations to Constitutivity and Hyperproduction . . . . . . . . . . . . 134 d) Increase in Gene Copies . . . . . . . . . . . . . . . . . . . . . . 137 4. The Future of Fermentation . . . . . . . . . . . . . . . . . . . . 138 Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . 139 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

Hyperinducibility as a Result of Mutation in Structural Genes and Self-Catabolite Repression in the ara Operon

Abstract: Mutations in gene araB producing an l-arabinose-negative phenotype cause either an increase (hyperinducible), decrease (polar), or have no effect at all on the inducible rate of expression of the l-arabinose operon. Fourteen araB gene mutants exhibiting such effects were shown to be the result of: nonsense, frameshift, or missense mutations. All missense mutants were hyperinducible, exhibiting approximately a twofold increase in rate of l-arabinose isomerase production. All frameshift and most nonsense mutants exhibited polar effect. One nonsense mutant was hyperinducible. The cis-dominant polar effect of nonsense and frameshift mutants (as compared to induced wild type) were more pronounced in arabinose-utilizing merodiploids and in araBaraCc double mutants where inducible and constitutive enzyme levels are respectively determined. On the other hand, in arabinose-utilizing merodiploids, missense mutations no longer exhibited hyperinducibility but displayed a wild-type level of operon expression. Increases in the wild type-inducible rate of expression of the operon were found when growth rate was dependent on the concentration of l-arabinose. Cyclic 3′,5′-adenosine monophosphate also stimulated expression of the operon with the wild type in a mineral l-arabinose medium. These observations are explained on the basis that the steady-state expression of the l-arabinose operon OIBAD is dependent on the concentration of (i) l-arabinose, the effector of this system, which stimulates the expression of the operon, and (ii) catabolite repressors, produced from l-arabinose, which dampen the expression of the operon. We have termed the latter phenomenon “self-catabolite” repression.

Regulation of cellulase production by Myrothecium verrucaria grown on non-cellulosic substrates.

Abstract: SUMMARY: Myrothecium verrucaria can produce cellulase when grown on media containing glucose or glycerol as sole carbohydrate source. The enzyme complex can depolymerize cellulosic substrates ranging from carboxymethylcellulose to cotton fibres. Hemicellulase is also produced. These depolymerases are first detected intracellularly near the time of the deceleration phase of growth and appear extracellularly a few hours later. Since cellulase can be produced by reducing the organism's growth rate in the absence of cellulose or any of its constituent sugars, it is suggested that this enzyme is constitutive and that production may be partly controlled by catabolite repression.

Metabolic Role, Regulation of Synthesis, Cellular Localization, and Genetic Control of the Glyoxylate Cycle Enzymes in Neurospora crassa

Abstract: The glyoxylate shunt enzymes, isocitrate lyase and malate synthase, were present at high levels in mycelium grown on acetate as sole source of carbon, compared with mycelium grown on sucrose medium. The glyoxylate shunt activities were also elevated in mycelium grown on glutamate or Casamino Acids as sole source of carbon, and in amino acid-requiring auxotrophic mutants grown in sucrose medium containing limiting amounts of their required amino acid. Under conditions of enhanced catabolite repression in mutants grown in sucrose medium but starved of Krebs cycle intermediates, isocitrate lyase and malate synthase levels were derepressed compared with the levels in wild type grown on sucrose medium. This derepression did not occur in related mutants in which Krebs cycle intermediates were limiting growth but catabolite repression was not enhanced. No Krebs cycle intermediate tested produced an efficient repression of isocitrate lyase activity in acetate medium. Of the two forms of isocitrate lyase in Neurospora, isocitrate lyase-1 constituted over 80% of the isocitrate lyase activity in acetate-grown wild type and also in each of the cases already outlined in which the glyoxylate shunt activities were elevated on sucrose medium. On the basis of these results, it is concluded that the synthesis of isocitrate lyase-1 and malate synthase in Neurospora is regulated by a glycolytic intermediate or derivative. Our data suggest that isocitrate lyase-1 and isocitrate lyase-2 are the products of different structural genes. The metabolic roles of the two forms of isocitrate lyase and of the glyoxylate cycle are discussed on the basis of their metabolic control and intracellular localization.

Induction Specificity and Catabolite Repression of the Early Enzymes in Camphor Degradation by Pseudomonas putida

Abstract: The ability of bornane and substituted bornanes to induce the early enzymes for d(+)-camphor degradation and control of these enzymes by catabolite repression were studied in a strain of a Pseudomonas putida. Bornane and 20 substituted bornane compounds showed induction. Of these 21 compounds, bornane and 8 of the substituted bornanes provided induction without supporting growth. Oxygen, but not nitrogen, enhanced the inductive potency of the unsubstituted bornane ring. All bornanedione isomers caused induction, and those with substituents on each of the three consecutive carbon atoms, including the methyl group at the bridgehead carbon, showed induction without supporting growth. Although it was not possible to obtain experimental data for a case of absolute gratuitous induction by compounds not supporting growth, indirect evidence in support of gratuitous induction is presented. It is proposed that the ability of P. putida to tolerate the unusually high degree of possible gratuitous induction observed for camphor catabolism may be related to the infrequent occurrence of bicyclic ring structures in nature. Survival of an organism with a broad specificity for gratuitous induction is discussed. Glucose and succinate, but not glutamate, produced catabolite repression of the early camphor-degrading enzymes. Pathway enzymes differ in their degree of sensitivity to succinate-provoked catabolite repression. The ability of a compound to produce catabolite repression is not, however, directly related to the duration of the lag period (diauxic lag) between growth on camphor and growth on the repressing compound.

Characterization and Regulation of Protease Synthesis and Activity in Bacillus licheniformis

Abstract: Extracts of growing and sporulating cells contain a protease activity that has a broad pH optimum and an unusually broad specificity. The activity, which resides in at least two protein fractions, hydrolyzes all peptide bonds and can reduce a mixture of proteins into a mixture of free amino acids with a high efficiency. No inhibitors of the activity were found, but the protease showed a definite preference for denatured protein as substrate. The synthesis of the intracellular protease activity is under catabolite repression control, as is the extracellular activity. However, the synthesis of the two activities is not coordinate, making the relationship between the two unclear. Due to (i) the specificity of the intracellular activity, (ii) the fact that it is synthesized most rapidly under slow or nongrowing conditions, and (iii) our inability to measure in vivo protein turnover in cells containing high levels of enzyme, a scavenger role is postulated for the enzyme. The rate of protein turnover is not a function of the protease content of the cells.

d-Fucose as a Gratuitous Inducer of the l-Arabinose Operon in Strains of Escherichia coli B/r Mutant in Gene araC

Abstract: d-Fucose, a nonmetabolizable analogue of l-arabinose, prevents growth of Escherichia coli B/r on a mineral salts medium plus l-arabinose by inhibiting induction of the l-arabinose operon. Mutations giving rise to d-fucose resistance map in gene araC and result in constitutive expression of the l-arabinose operon. Most of these mutations also permit d-fucose to serve as a gratuitous inducer. It is concluded that d-fucose-resistant mutants produce an araC gene product with an altered inducer specificity. Addition of l-arabinose to cells induced with the gratuitous inducer, d-fucose, resulted in severe transient repression of operon expression followed by permanent catabolite repression. Transient repression but no permanent catabolite repression was obtained when cells unable to metabolize l-arabinose were employed. It is concluded that transport of l-arabinose alone is sufficient to achieve transient repression of its own operon, but that metabolism of l-arabinose must occur to achieve permanent catabolite repression of the l-arabinose operon. This general effect has been termed "self-catabolite repression."

CHAPTER 9 – Regulation in the L-Arabinose System

Abstract: Publisher Summary This chapter presents the regulation in the L-arabinose system. The L-arabinose regulon, besides being specifically regulated through the effect of L-arabinose on the repressor–activator equilibrium, is subject to self-catabolite repression, that is, feedback repression caused by intermediates produced from L-arabinose. There is evidence in the lac operon and indirectly in the ara regulon that catabolite repression functions at the level of transcription. In addition, the lac repressor appears to function at the transcriptional level. Measurements of the in vivo rate of synthesis of ara operon mRNA suggests that activator functions at the level of transcription. Besides the L-arabinose-positive revertants, the great majority of the revertants are double mutants containing the original D-mutant site plus another mutation in the ara A, ara B, or ara C genes. The phenotypic effect of gene ara C is modified by mutations in the controlling sites of the operon is strong evidence that gene ara C is a regulatory gene as postulated in the positive control model. Presumably, the repressor also functions at the transcription level because the operator region is probably not transcribed. The mechanism of action of this regulatory protein is unknown and will have to await its purification.

Promoter-Like Mutant with Increased Expression of the Glycerol Kinase Operon of Escherichia coli

Abstract: A glycerol-specific phenotypic revertant isolated from a mutant of Escherichia coli missing enzyme I of the phosphoenolpyruvate phosphotransferase system was studied. This revertant is capable of producing higher levels of glycerol kinase and the protein mediating the facilitated diffusion of glycerol (facilitator) than wild-type cells. The kinase of the revertant is indistinguishable from the wild-type enzyme with respect to its sensitivity to feedback inhibition by fructose-1,6-diphosphate, its pH optimum, and its turnover number. The synthesis of glycerol kinase in strains bearing the suppressor locus is resistant to catabolite repression. The suppressor mutation mapped at the known glpK locus. Thus, it is suggested that the mutation occurred in the promoter of the operon specifying the kinase and the facilitator.

Cyclic adenosine 3',5'-monophosphate during glucose repression in the rat liver.

Abstract: Intragastric administration of glucose inhibits the induction of serine dehydratase and tyrosine aminotransferase by glucagon in rat liver, but has no effect on the increase in hepatic adenosine 3',5'-monophosphate resulting from administration of glucagon. Thus, glucose repression in mammalian liver, unlike catabolite repression in microorganisms, appears to operate independently of the amounts of cyclic nucleotide in the cells.

10 Yeast and Neurospora Invertases

Abstract: Publisher Summary This chapter focuses on invertases formed by yeast ( Saccharomyces species) and by the fungus Neurospora crassa. Almost all of the invertase produced by yeast is retained by the intact cell, although a few yeasts release most of their enzyme. External invertase can be released from cells of Saccharomyces fragilis and S. mellis (but not S. cerevisiae ) by treatment with thiols. Invertase is released from several Saccharomyces strains by phosphomannanase, which removes an outer wall layer of P-diester-linked mannan from the yeast cell, but very little protein or glucan. External invertase is held within the wall or between the wall and cell membrane with the structures responsible for its retention varying from one species to another. The formation of invertase by yeast and by N. crassa is primarily controlled by catabolite repression, particularly by hexoses. The usual procedures for the extraction and purification of invertase include a prolonged autolysis to release the enzyme and degrade most of the noninvertase protein, a heat treatment to precipitate the yeast gum (mostly mannan), and various precipitations or adsorptions of the enzyme. More recent attempts utilize gel filtration, ion exchange chromatography, gel electrophoresis, and electrofocusing.

[148] Histidine degradation (Bacillus subtilis)

Abstract: Publisher Summary This chapter focuses on Histidine Degradation ( Bacillus subtilis ). Bacillus subtilis degrades L -histidine to ammonia, L -glutamic acid, and formamide by the series of four enzymatic steps. These reactions enable the organism to use histidine as a source of L -glutamate. The glutamate formed may be used as a general source of carbon and energy for growth; the ammonia and glutamate formed may also serve as general sources of nitrogen. The enzymes responsible for the degradation of histidine are found in extracts prepared from cells cultivated in media containing a poor carbon source such as citric acid or glutamic acid, an ammonium salt, and histidine. The levels of the enzymes are greatly reduced by the omission of histidine from the medium or the inclusion of glucose in the medium. Thus, the enzymes of histidine degradation are inducible and subject to catabolite repression. This susceptibility to catabolite repression explains the failure of B. subtilis to grow in a medium containing glucose as source of carbon and histidine as sole source of nitrogen.

Pressure Sensitivity of Streptococcal Growth in Relation to Catabolism

Abstract: The sensitivity of Streptococcus faecalis growth to hydrostatic pressures ranging up to 550 atm was found to depend on the source of adenosine triphosphate for growth. Barotolerance of cultures growing in a complex medium with ribose as major catabolite appeared to be determined primarily by the pressure sensitivity of ribose-degrading enzymes. Apparent activation volumes for growth were nearly identical to those for lactate production from ribose, and yield coefficients per mole of ribose degraded were relatively independent of pressure. In contrast, cultures with glucose as main catabolite were less sensitive to pressure; glycolysis was less severely restricted under high pressure than was growth, and yield coefficients declined with pressure, especially above 400 atm. Thus, two distinct types of barotolerance could be defined—one dominated by catabolic reactions and one dominated by noncatabolic reactions. The results of experiments with a series of other catabolites further supported the view that catabolic reactions can determine streptococcal barotolerance. We also found that growing, glucose-degrading cultures increased in volume under pressure in the same manner that they do at 1 atm. Thus, it appeared that the bacterium has no alternative means of carrying out glycolysis under pressure without dilatation. Also, the observation that cultures grown under pressure did not contain abnormally large or morphologically deformed cells suggested that pressure did not inhibit cell division more than cell growth.

Catabolite Repression in the d-Serine Deaminase System of Escherichia coli K-12

Abstract: The induced synthesis of d-serine deaminase in Escherichia coli is subject to three catabolic effects: inhibition on inducer uptake, transient repression, and catabolite repression. Inhibition on d-serine uptake is not significant at the d-serine concentration normally used for induction. Transient repression and catabolite repression of d-serine deaminase synthesis are abolished by mutations in dsdCy, which appears to be an operator locus. The decline in the rate of constitutive synthesis observed in dsdCx mutants growing with glycerol as carbon source at temperatures above 37 C is due to catabolite repression. The low level of constitutivity at 37 C and the partial cis dominance of dsdCx mutants are not artifacts of catabolite repression. It is suggested that a product of one of the genes of the dsd operon may regulate the expression of the operon.

Induction and repression of L-arabinose isomerase in Salmonella typhimurium.

Abstract: As with other inducible enzymes, the induced synthesis of l-arabinose isomerase (l-arabinose ketol isomerase, EC 5.3.1.4) in Salmonella typhimurium is subject to catabolite repression. Of the three catabolite repressors tested, glucose produces maximum repression. Analogues of catabolite repressors like 2-deoxy-d-glucose and d-fucose also inhibit the synthesis of the enzyme. The catabolite repression is completely reversed in the presence of 1.5 × 10−3m cyclic 3′,5′-adenosine monophosphate (AMP). The maximum repression is produced in glucose-grown cells in glucose-containing induction medium. Cyclic 3′,5-AMP reverses this repression provided that the cells are treated with ethylenediaminetetraacetic acid (EDTA). In normal cells, cyclic 3′,5′-AMP has no effect on the induction but in EDTA-treated cells the cyclic nucleotide enhances synthesis of the enzyme. The inhibition produced by d-fucose cannot be reversed by cyclic 3′,5′-AMP. d-Fucose competes with the inducer l-arabinose in some step(s) involved in the process of induction.

[12] Increasing enzyme production by genetic and environmental manipulations

Abstract: Publisher Summary The amounts of a particular enzyme produced by a particular microorganism can vary tremendously because enzyme formation is regulated in both positive and negative directions by such control mechanisms as induction, end product repression, and catabolite repression. Because each control mechanism is influenced by environmental conditions, traditional factors important in enzyme production are temperature, pH, medium composition, aeration, and the stage of the growth cycle. These conditions are usually determined empirically for each enzyme and each strain and are not be considered further unless they apply to the specific type of control mechanism. This chapter focuses on several manipulations that can be used to modify, to bypass, or to utilize regulatory mechanisms to force “overproduction” of enzymes in the laboratory. The manipulations discussed are grouped into the several categories—(1) environmental, such as addition of inducers and decreasing concentration of repressors and (2) genetic, such as mutation to constitutivity and increasing gene copies.

Some aspects of catabolite repression of mitochondrial enzymes in Saccharomyces cerevisiae.

Abstract: The synthesis of mitochondrial enzymes inSaccharomyces cerevisiae is partly derepressed during growth with maltose as compared with glucose. The present investigations were aimed at finding any more differences between maltose- and glucose-grown cultures that might indicate the nature of the effector(s) of catabolite repression.

Accumulation of untranslated lactose-specific messenger ribonucleic acid during catabolite repression in Escherichia coli

Abstract: When Escherichia coli K-12 Hfr.H was induced to synthesize beta-galactosidase in the presence of glucose, an untranslated lactose-specific mRNA (lac-mRNA), protected from decay, was found to accumulate progressively within the cells. The lac-mRNA accumulation was unaffected by the carbon source on which the cells had been grown before the induction. The amount of the lac-mRNA available for translation was affected by catabolite repression and 3':5'-cyclic AMP, but it remained unclear whether this was a direct effect on the formation of the lac-mRNA or a consequence of the effect on its translation.