Showing papers on "Catabolite repression published in 1969"
TL;DR: This chapter focuses on three devices: catabolite repression, transient repression, and catabolites inhibition, which regulate the utilization of many carbohydrates, which influences many aspects of microbial growth and metabolism.
Abstract: Publisher Summary This chapter focuses on three devices: catabolite repression, transient repression, and catabolite inhibition, which regulate the utilization of many carbohydrates. Catabolite repression is a reduction in the rate of synthesis of certain enzymes, particularly those of degradative metabolism, in the presence of glucose or other readily metabolized carbon sources. Catabolite inhibition is a control exerted by glucose on enzyme activity rather than on enzyme formation, analogous to feedback inhibition in biosynthetic pathways. Catabolite repression influences many aspects of microbial growth and metabolism. In addition to the well known repressions of carbohydrate utilization and amino-acid degradation in bacteria and yeast, catabolite repression affects the formation of enzymes that function in the tricarboxylic acid cycle, glyoxylate cycle, fatty acid degradation, carbon dioxide fixation, and the respiratory chain. In higher organisms, catabolite repression has been observed in sugar cane, rats, and man. The question of whether catabolite repression acts to inhibit the transcription of DNA into m-RNA or to inhibit translation of messenger into protein has received conflicting answers. Catabolite repression is a control system that usually affects catabolic enzymes. If catabolite repression and transient repression are not mediated by the specific apo-repressor of each operon, there must be another protein that recognizes the low molecular-weight effector. The significance of a control mechanism, which influences the activity as opposed to the concentration of a carbohydrate-metabolizing enzyme is readily appreciated because bacteria have a limited ability to change enzyme concentrations.
163 citations
TL;DR: Transient and catabolite repression of the synthesis of β-galactosidase in E. coli are related phenomena, the result of a decreased intracellular concentration of cyclic AMP.
Abstract: Transient and catabolite repression of the synthesis of β-galactosidase in E. coli are related phenomena, the result of a decreased intracellular concentration of cyclic AMP. The lac operon promoter is the site of action of the cyclic AMP.
157 citations
TL;DR: Escherichia coli grows on long-chain fatty acids after a distinct lag phase, indicating that fatty acid oxidation in this bacterium is an inducible system and the inhibitory effect of glucose may be explained in terms of catabolite repression.
Abstract: Escherichia coli grows on long-chain fatty acids after a distinct lag phase. Cells, preadapted to palmitate, grow immediately on fatty acids, indicating that fatty acid oxidation in this bacterium is an inducible system. This hypothesis is supported by the fact that cells grown on palmitate oxidize fatty acids at rates 7 times faster than cells grown on amino acids and 60 times faster than cells grown on a combined medium of glucose and amino acids. The inhibitory effect of glucose may be explained in terms of catabolite repression. The activities of the five key enzymes of beta-oxidation [palmityl-coenzyme A (CoA) synthetase, acyl-CoA dehydrogenase, enoyl-CoA hydrase, beta-hydroxyacyl-CoA dehydrogenase, and thiolase] all vary coordinately over a wide range of activity, indicating that they are all under unit control. The ability of a fatty acid to induce the enzymes of beta-oxidation and support-growth is a function of its chain length. Fatty acids of carbon chain lengths of C(14) and longer induce the enzymes of fatty acid oxidation and readily support growth, whereas decanoate and laurate do not induce the enzymes of fatty acid oxidation and only support limited growth of palmitate-induced cells. Two mutants, D-1 and D-3, which grow on decanoate and laurate were isolated and were found to contain constitutive levels of the beta-oxidation enzymes. Short-chain fatty acids (
140 citations
TL;DR: It is concluded that E. coli has a general regulatory mechanism, termed catabolite inhibition, which controls the activity of early reactions in carbohydrate metabolism, allowing certain substrates to be utilized preferentially.
Abstract: When Escherichia coli is grown in synthetic medium with radioactive galactose or lactose as the carbon source, the addition of glucose rapidly inhibited utilization of the radioactive substrate, whether the formation of 14CO2 or acid-insoluble products was measured. The inhibition was reversed after the removal of glucose. Experiments with mutants blocked in subsequent steps of galactose and lactose metabolism demonstrated that the inhibition occurs prior to the formation of the first metabolic product. The utilization of a variety of sugars, including maltose, lactose, mannose, galactose, l-arabinose, xylose, and glycerol was inhibited by glucose. Of a number of carbohydrates tested as potential inhibitors, only glucose and, to a lesser extent, glucose-6-phosphate (G-6-P) were capable of inhibiting the utilization of all of the substrates. Glucose did not inhibit G-6-P utilization but G-6-P inhibited glucose utilization. With all substrates, except glycerol, there was a delay before the onset of inhibition by G-6-P. We conclude that E. coli has a general regulatory mechanism, termed catabolite inhibition, which controls the activity of early reactions in carbohydrate metabolism, allowing certain substrates to be utilized preferentially.
116 citations
TL;DR: Glucose and α-methyl glucoside repress β-galactosidase synthesis in wild type Escherichia coli and in mutant strains deficient in Enzyme I or in the heat-stable protein of the phosphoenolpyruvate-phosphotransferase system, apparently not required for lactose utilization by E. coli.
88 citations
TL;DR: A partial deletion in the lac p region makes the lac operon insensitive to catabolite repression.
Abstract: A partial deletion in the lac p region makes the lac operon insensitive to catabolite repression.
81 citations
TL;DR: A study of the effect of actinomycin D on the induced and noninduced (derepressed) synthesis of α-glucosidase showed that induction by maltose caused mRNA to be synthesized, which appeared to be stable under conditions of both repression and derepression.
69 citations
TL;DR: The chemostat culture technique was used to study the control mechanisms which operate during utilization of mixtures of glucose and lactose and glucose and l-aspartic acid by populations of Escherichia coli B6, and catabolite repression was shown to be the primary mechanism of control of beta-galactosidase level and lactOSE utilization.
Abstract: The chemostat culture technique was used to study the control mechanisms which operate during utilization of mixtures of glucose and lactose and glucose and l-aspartic acid by populations of Escherichia coli B6. Constitutive mutants were rapidly selected during continuous culture on a mixture of glucose and lactose, and the β-galactosidase level of the culture increased greatly. After mutant selection, the specific β-galactosidase level of the culture was a decreasing function of growth rate. In cultures of both the inducible wild type and the constitutive mutant, glucose and lactose were simultaneously utilized at moderate growth rates, whereas only glucose was used in the inducible cultures at high growth rates. Catabolite repression was shown to be the primary mechanism of control of β-galactosidase level and lactose utilization in continuous culture on mixed substrates. In batch culture, as in the chemostat, catabolite repression acting by itself on the lac enzymes was insufficient to prevent lactose utilization or cause diauxie. Interference with induction of the lac operon, as well as catabolite repression, was necessary to produce diauxic growth. Continuous cultures fed mixtures of glucose and l-aspartic acid utilized both substrates at moderate growth rates, even though the catabolic enzyme aspartase was linearly repressed with increasing growth rate. Although the repression of aspartase paralleled the catabolite repression of β-galactosidase, l-aspartic acid could be utilized even at very low levels of the catabolic enzyme because of direct anabolic incorporation into protein.
67 citations
TL;DR: Two mutants of E. coli differ from a wild type strain, sensitive to catabolite repression, in having a defective 3′, 5′ cyclic AMP degradative system.
66 citations
TL;DR: It is concluded that while the synthesis of citrate synthase is sensitive to both anabolic and catabolic signals, once the enzyme is formed, its activity is regulated primarily by catabolic effectors.
64 citations
TL;DR: Observations indicate that production of PGA trans-eliminase is subject to catabolite repression and that limiting the substrate reverses this repression, and that A. liquefaciens, contrary to the current view, appears to be constitutive.
Abstract: Production of polygalacturonic acid (PGA) trans-eliminase was greatly stimulated under conditions of restricted growth of Aeromonas liquefaciens This was accomplished either by substrate restriction in a continuous-feeding culture or by restricting divalent cations in a batch culture, with the use of PGA as the sole source of carbon in a chemically defined medium containing inorganic nitrogen Slow feeding of glucose, glycerol, or PGA to carbon-limited cultures allowed PGA trans-eliminase to be formed at a maximum differential rate 500 times greater than in batch cultures with excess substrate present The differential rate of enzyme formation obtained by slow feeding of these three substrances or of a mixture of PGA plus glucose was observed to be the same Therefore, PGA trans-eliminase produced by A liquefaciens, contrary to the current view, appears to be constitutive These observations also indicate that production of PGA trans-eliminase is subject to catabolite repression and that limiting the substrate reverses this repression It was also found that, under conditions of unrestricted growth, any compound which the bacteria can use as a source of carbon and energy repressed constitutive PGA trans-eliminase production The heritable reversal of catabolite repression of PGA trans-eliminase synthesis was demonstrated by isolation of mutant strain Gc-6 which can readily synthesize the constitutive catabolic enzyme PGA trans-eliminase while growing in the presence of excess substrate
TL;DR: Several factors influenced the formation of enterotoxin B by Staphylococcus aureus strain S-6; the presence of toxin was dependent on de novo protein synthesis and toxin synthesis appeared to be regulated by catabolite repression.
Abstract: Several factors influenced the formation of enterotoxin B by Staphylococcus aureus strain S-6. In the standard casein hydrolysate medium, toxin was not produced in detectable quantities during exponential growth; it was produced during the post-exponential phase when total protein synthesis was arithmetic. The rate of toxin synthesis was much greater than the rate of total protein synthesis. The appearance of enterotoxin was inhibited by chloramphenicol; thus, the presence of toxin was dependent on de novo protein synthesis. When low concentrations of glucose ( p H resulting from the acid end products of glucose metabolism. At p H p H above 5.6. In such media, the differential rates of toxin synthesis, with respect to the rates of total protein synthesis, were lower than the differential rates in casein hydrolysate medium alone. Addition of glucose to a culture synthesizing toxin resulted in an immediate decrease in the differential rate without any change in p H. Thus, toxin synthesis appeared to be regulated by catabolite repression.
TL;DR: In addition to inducing the degradative enzymes, the two hydroxyproline epimers were also found to induce an uptake system that concentrates hydroxy Proline intracellularly and either amino acid induced the uptake system for its epimer as well as for itself.
Abstract: Studies in Pseudomonas putida of the inducible degradation of hydroxyproline to α-ketoglutarate have indicated that either of the two epimers, hydroxy-l-proline or allohydroxy-d-proline, acts as an inducer of all the pathway enzymes. In a mutant lacking the first enzyme of the sequence, hydroxyproline-2-epimerase, which interconverts these two hydroxyproline epimers, either epimer is still equally active as an inducer of the remaining three enzymes, suggesting that each epimer has intrinsic inducer activity. The second and third enzymes of the sequence were induced coordinately. The induction process appeared to be insensitive to catabolite repression under a number of experimental conditions. The induced enzymes were stable even under conditions of nitrogen starvation and other conditions designed to increase protein turnover. In addition to inducing the degradative enzymes, the two hydroxyproline epimers were also found to induce an uptake system that concentrates hydroxyproline intracellularly. Either amino acid induced the uptake system for its epimer as well as for itself.
TL;DR: A catabolite repression gene (cat) which alters the sensitivity of Escherichia coli to catabolic repression has been mapped by transduction and shown to be located between the pyrC and purB genes.
Abstract: A catabolite repression gene (cat) which alters the sensitivity of Escherichia coli to catabolite repression has been mapped by transduction and shown to be located between the pyrC and purB genes. When the cat-1 mutation was studied in a number of genetic backgrounds, the results showed that this mutation affects the synthesis of more than one catabolic enzyme but does not completely eliminate catabolic repression under all conditions. It is suggested that this mutation may cause a block in the accumulation of the catabolite effector. Our experiments show that this effector is not glucose-6-phosphate.
TL;DR: Data indicate that various inducing conditions affect the relative proportions of tryptophan oxygenase and kynurenine formamidase, and thus indicate noncoordinate regulation of these enzyme activities.
Abstract: The process of induction of tryptophan oxygenase in Pseudomonas acidovorans is typical of many microbial enzyme induction systems, in that it (i) requires cell multiplication and de novo protein synthesis, (ii) is subject to catabolite repression, (iii) results in the formation of a stable enzyme, whose level, upon removal of inducer, is diluted out by cell proliferation, and (iv) exhibits product induction. l-Kynurenine was more effective than l-tryptophan as an inducer of both tryptophan oxygenase and the second enzyme of the pathway, kynurenine formamidase. The occurrence of product induction of these two enzymes by their common metabolite eliminated the possibility of sequential induction of these enzymes. dl-5-Fluorotryptophan, nonmetabolizable and devoid of any inducing activity, resulted in a concentration-dependent inhibition of the l-tryptophan-mediated induction of tryptophan oxygenase; kynurenine formamidase induction, however, was not influenced by the presence of dl-5-fluorotryptophan. dl-7-Azatryptophan, also nonmetabolizable and completely inactive as an inducer, acted synergistically with l-tryptophan and superinduced tryptophan oxygenase levels. When induction was conducted in a medium containing only l-tryptophan and 7-azatryptophan as inducing agents, then tryptophan oxygenase induction was enhanced, whereas the kynurenine formamidase level was essentially unchanged. These data indicate that various inducing conditions affect the relative proportions of tryptophan oxygenase and kynurenine formamidase, and thus indicate noncoordinate regulation of these enzyme activities.
TL;DR: It is concluded that repression of beta-galactosidase synthesis can be brought about by the presence of glucose during the translation phase only, and in E. coli strain 300U the effect on translation was sufficient to account for almost all the catabolite repression ofBeta-galacticase synthesis observed during exponential growth of the organism in glucose-minimal medium.
Abstract: 1. Experiments were devised to show whether catabolite repression of beta-galactosidase synthesis operates at the level of transcription or of translation. Escherichia coli K12 was induced for a short period in non-repressing medium (glycerol-minimal medium), and transcription of the lac operon was terminated by either of two methods; glucose was then added as a source of the catabolite repressor during the subsequent translation of the accumulated beta-galactosidase messenger RNA. 2. When induced bacteria in glycerol medium were infected with T6 phage, which is known to halt transcription, the addition of glucose up to 3min. later diminished the yield of beta-galactosidase. 3. When induced bacteria in glycerol medium were removed from the inducer and resuspended in fresh medium (a process that is also known to halt transcription), the yield of enzyme was again diminished by the presence of glucose in the resuspension medium. 4. It is concluded that repression of beta-galactosidase synthesis can be brought about by the presence of glucose during the translation phase only. 5. In E. coli strain 300U the effect on translation was sufficient to account for almost all the catabolite repression of beta-galactosidase synthesis observed during exponential growth of the organism in glucose-minimal medium. In E. coli strain 200P, however, much more severe repression occurred during exponential growth, and an additional effect of glucose is postulated.
TL;DR: It was discovered that the rate at which Aerobacter aerogenes cells grow under a biosynthetic restriction determines both the rate and the pattern of histidine degradation.
Abstract: A study was made of how the catabolism of a carbon and energy source is affected by the biosynthetic demands of growing bacterial cells. Cultures of Aerobacter aerogenes in l-histidine medium were grown in a chemostat at rates determined by the supply of either sulfate or a required amino acid, l-arginine. It was discovered that the rate at which these cells grow under a biosynthetic restriction determines both the rate and the pattern of histidine degradation. (i) Histidine catabolism is partially coupled to the growth rate. This coupling is achieved by catabolite repression of histidase (histidine ammonia lyase; EC 4.3.1.3.), and also by a slightly decreased in vivo function of this enzyme at low growth rates. (ii) The looseness of the coupling results in a direct relationship between growth rate and growth yield, and possibly is correlated with an altered pattern of carbon flow from histidine. (iii) Sudden decreases in growth rate cause total repression of histidase synthesis for substantial periods of time. (iv) Sudden release of biosynthetic restriction leads rapidly to an increase in the functioning of the cells' complement of histidase, an increase in the rate of synthesis of this enzyme, and an increase in the growth yield from histidine.
TL;DR: It is concluded that the decreased efficiency of glucose utilization in streptomycin-dependent E. coli B is responsible for the relaxation of catabolite repression in this mutant.
Abstract: Acetohydroxy acid synthetase, which is sensitive to catabolite repression in wild-type Escherichia coli B, was relatively resistant to this control in a streptomycin-dependent mutant. The streptomycin-dependent mutant was found to be inducible for beta-galactosidase in the presence of glucose, although repression of beta-galactosidase by glucose occurred under experimental conditions where growth of the streptomycin-dependent mutant was limited. Additional glucose-sensitive enzymes of wild-type E. coli B (citrate synthase, fumarase, aconitase and isocitrate dehydrogenase) were found to be insensitive to the carbon source in streptomycin-dependent mutants: these enzymes were formed by streptomycin-dependent E. coli B in equivalent quantities when either glucose or glycerol was the carbon source. Two enzymes, glucokinase and glucose 6-phosphate dehydrogenase, that are glucose-insensitive in wild-type E. coli B were formed in equivalent quantity on glucose or glycerol in both streptomycin-sensitive and streptomycin-dependent E. coli B. The results indicate a general decrease or relaxation of catabolite repression in the streptomycin-dependent mutant. The yield of streptomycin-dependent cells from glucose was one-third less than that of the streptomycin-sensitive strain. We conclude that the decreased efficiency of glucose utilization in streptomycin-dependent E. coli B is responsible for the relaxation of catabolite repression in this mutant.
TL;DR: No correlation was found between the cellular steady-state concentrations of glucose-6-phosphate, 6phosphogluconate, and reduced nicotinamide dinucleotide phosphate and resistance versus sensitivity to catabolite repression as mentioned in this paper.
Abstract: No correlation was found between the cellular steady-state concentrations of glucose-6-phosphate, 6-phosphogluconate, and reduced nicotinamide dinucleotide phosphate and resistance versus sensitivity to catabolite repression.
TL;DR: It is concluded that in strain RM32/F'd25 the synthesis of beta-galactosidase is subject to both transcriptional and translational repression.
Abstract: 1. Experiments were carried out to distinguish the contributions of transcriptional and translational repression to catabolite repression of the lac operon. 2. In strain EZ16-3-G of Escherichia coli the synthesis of thiogalactoside transacetylase is directed by a gene situated on an episome, and the operator, promotor and regulator genes that lay cis to this gene have been deleted, so that the normal mechanism for controlling transcription is abolished. The extent of catabolite repression in this strain was much less than that in wild-type strains. 3. The same episome is responsible for the synthesis of thiogalactoside transacetylase in strain RM32/F'd25, and in this strain a second lac operon directs the synthesis of beta-galactosidase under the control of a wild-type operator-promotor-regulator system. The extent of catabolite repression of thiogalactoside transacetylase in strain RM32/F'd25 was substantially more than in strain EZ16-3-G, but less than that of beta-galactosidase in strain RM32/F'd25. 4. Since the synthesis of thiogalactoside transacetylase in these organisms is presumably subject to translational repression only, it is concluded that in strain RM32/F'd25 the synthesis of beta-galactosidase is subject to both transcriptional and translational repression. It is also concluded that the extent of translational repression varies between strains.
TL;DR: The gluconeogenic enzyme phosphoenolpyruvate (PEP) carboxykinase is glucose repressible in Escherichia coli and other carbohydrates tested, excluding lactose, are much less effective, and pyruVate is completely ineffective in producing catabolite repression.
TL;DR: A class of galactose-resistant mutants has been derived from strains of Salmonella typhimurium which are defective in uridine diphosphoglucose-4-epimerase, and the leaky nature of these mutants may account for resistance to galactoses death by maintaining galactOSE metabolites at a subcritical level.
Abstract: A class of galactose-resistant mutants has been derived from strains of Salmonella typhimurium which are defective in uridine diphosphoglucose-4-epimerase. Resistant strains are phenotypically similar to parent organisms but do not lyse in the presence of galactose. Low levels of functional epimerase can be detected in induced cells grown at 20 C but not at 37 C, and acid is not produced from galactose. Sufficient galactose is synthesized at reduced temperatures to fabricate smooth lipopolysaccharide and acceptor sites for phage P22 from galactose-deficient media. The leaky nature of these mutants may account for resistance to galactose death by maintaining galactose metabolites at a subcritical level. Glucose protects sensitive strains by control of levels of toxic metabolites by catabolite repression.
TL;DR: The results suggest that acetohydroxy acid synthetase may play an amphibolic role in E. coli B.
Abstract: 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.
TL;DR: It is concluded that there is no part of the structural gene for beta-galactosidase that is essential for catabolite repression of thiogalactoside transacetylase and that catabolites repression is separate but equal.
Abstract: 1. Catabolite repression of β-galactosidase and of thiogalactoside transacetylase was studied in several strains of Escherichia coli K 12, in an attempt to show whether a single site within the structural genes of the lac operon co-ordinately controls translational repression for the two enzymes. In all experiments the rate of synthesis of the enzymes was compared in glycerol–minimal medium and in glucose–minimal medium. 2. In a wild-type strain, glucose repressed the synthesis of the two enzymes equally. 3. The possibility that repression was co-ordinate was investigated by studies of mutant strains that carry deletions in the genes for β-galactosidase or galactoside permease or both. In all of the strains with deletions, the repression of thiogalactoside transacetylase persisted, and it is concluded that there is no part of the structural gene for β-galactosidase that is essential for catabolite repression of thiogalactoside transacetylase. 4. Subculture of one strain through several transfers in rich medium greatly increased its susceptibility to catabolite repression by glucose. It is concluded that unknown features of the genotype can markedly affect sensitivity to catabolite repression. 5. These results make it clear that one cannot draw valid conclusions about the effect of known genotypic differences on catabolite repression from a comparison of two separate strains; to study the effect of a particular genetic change in a lac operon it is necessary to construct a partially diploid strain so that catabolite repression suffered by one lac operon can be compared with that suffered by another. 6. Four such partial diploids were constructed. In all of them catabolite repression of β-galactosidase synthesized by one operon was equal in extent to catabolite repression of thiogalactoside transacetylase synthesized by the other. 7. Taken together, these results suggest that catabolite repression of β-galactosidase and thiogalactoside transacetylase is separate but equal.
TL;DR: It is shown that at concentrations less than 10(-4)m, AcGN caused severe catabolite repression of beta-galactosidase synthesis in cultures grown under either nonrepressed or partially repressed conditions, demonstrating that the AcGN effect does not involve the uptake of inducer.
Abstract: Acetylated amino sugars, normally used in the biosynthesis of cell walls and cell membranes, were found to play a role as corepressors for catabolite repression of the lac operon in Escherichia coli. This conclusion was derived from studies conducted on mutants of E. coli that were able to assimilate an exogenous source of N-acetylglucosamine (AcGN) but were unable to dissimilate or grow on this compound. At concentrations less than 10(-4)m, AcGN caused severe catabolite repression of beta-galactosidase synthesis in cultures grown under either nonrepressed or partially repressed conditions. This repression occurred in the absence of any effect of AcGN on either the carbon and energy metabolism or the growth of the organism. In addition, this repression by AcGN occurred in a mutant strain that is constitutive for beta-galactosidase production, demonstrating that the AcGN effect does not involve the uptake of inducer. This model for the corepressor system of catabolite repression is discussed in relation to the existing theories on repression of the lac operon.
TL;DR: Escherichia coli RC rel strains exhibit an unusually long induction lag following unbalanced RNA synthesis, and induced enzyme synthesis is impaired; general protein synthesis and constitutive enzyme production occur during this period.
TL;DR: Conclusively glycolytic steps may be associated with catabolite repression of tryptophanase synthesis in E. coli K12 and was pronounced also in β-galactosidase system.
Abstract: Catabolite repression of tryptophanase formation in E. coli K12 TAB40 was examined. Glycerol or pyruvate, if given as a sole carbon source, did not repress tryptophanase formation unlike glucose, but if they existed together, they repressed the enzyme formation like glucose. This synergistic effect was well observed in the wild strain of E. coli K12 and was pronounced also in β-galactosidase system.The combination of glycerol or pyruvate with other carbon sources directly related to glycolysis repressed the enzyme formation, while succinate or ribose did less effectively. When cells were grown on various carbon sources, glucose, glycerate, and fructose were effective in repressing the enzyme formation. It was considered that the growth rate and catabolite repression might not necessarily be directly related. Even anaerobically grown cells could show catabolite repression. Inhibition of oxidative pyruvate decarboxylation or TCA cycle provoked catabolite repression. Conclusively glycolytic steps may be associated with catabolite repression of tryptophanase synthesis.
TL;DR: The results are not incompatible with the hypothesis that the primary site of action of dihydrostreptomycin in the dependent organism is an anabolic process, but the growth-limiting effect of antibiotic deprival appears to be augmented by catabolite repression.
Abstract: SUMMARY: The half-maximal growth rate of a streptomycin-dependent mutant of Escherichia coli B on limiting concentrations of dihydrostreptomycin varied with the nature (but not with the initial concentration) of the carbon source It was highest with gluconate, lower with glucose and glycerol and lowest with lactate Glucose-sensitive enzymes (acetohydroxy acid synthetase, fumarase, aconitase, citrate synthase and isocitric dehydrogenase) were specifically repressed by antibiotic limitation Parallelism was observed between decreasing dihydrostreptomycin concentration, decreasing growth rate and increasing catabolite repression of certain glucose-sensitive enzymes The results are not incompatible with the hypothesis that the primary site of action of dihydrostreptomycin in the dependent organism is an anabolic process (eg protein synthesis) However, the growth-limiting effect of antibiotic deprival appears to be augmented by catabolite repression