Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.6.1.1 (adenylate cyclase)
 19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study we have tried to answer the following questions: (1) is it possible for different catabolite-repressible genes, although submitted to the same control, to be expressed selectively depending upon the growth conditions, and (2) what is the effect of increasing the osmolarity of the medium on the intracellular level of cAMP? Two conditions were found to cause a continuous variation of intracellular cAMP levels during growth. With different strains, higher cAMP levels are required for induction of the tryptophanase gene than one required for induction of the lactose operon. cAMP has been provided externally in adenyl cyclase minus cells of a mutant that has been made permeable by EDTA treatment. Although external cAMP concentrations, 10 times higher than the usual intracellular levels, are required for induction of beta-galactosidase and tryptophanase, the difference of requirements of cAMP is maintained. An increase in the osmolarity of the medium by sucrose addition causes a fourfold decrease in the intracellular cAMP level. As a consequence this prevents the induction of tryptophanase whereas beta-galactosidase is still inducible. After pulse induction, a difference in the kinetics of expression of the tryptophanase and beta-galactosidase genes was found. Its relationship with the previous results is discussed.
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PMID:Different cyclic adenosine 3',5'-monophosphate requirements for induction of beta-galactosidase and tryptophanase. Effect of osmotic pressure on intracellular cyclic adenosine 3,5-monophosphate concentrations. 16 97

1. The effect of carbon source variation in bacterial growth media on their growth rate, inducible enzyme and cyclic AMP synthesis was examined: an inverse relationship between the culture's growth rate and its differential rate of inducible enzyme (tryptophanase and beta-galactosidase), and cyclic AMP synthesis was found. 2. The effect of the culture's growth phase on its sensitivity or resistance to glucose catabolite repression was determined in the wild type and a catabolite insensitive mutant (ABDROI): the wild type's sensitivity to glucose repression was not affected, whereas the insensitivity of the mutant was found to be limited to its early logarithmic phase of growth. At late log, or stationary phase, the mutant was found to be sensitive to glucose repression. 3. Examination of the kinetics of glucose uptake by the mutant, using alpha-[1 4-C] methyl-glucoside showed evidence for two transport systems each with a different affinity to glucose. A low affinity transport system (apparent Km of 3.4-10-minus 5 M) which appears mostly at the early logarithmic phase of growth. A high affinity transport system (apparent Km of 1.2-10-minus 5 M) which appears mostly at the late log and stationary phases of growth. 4. The effect of the culture density variation on its sensitivity to glucose repression showed that sensitivity to glucose catabolic repression is primarily a reflection of the formation of an allosteric effector molecule between glucose and its specific transport molecule which in turn regulates the activity of the adenylate cyclase.
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PMID:On the regulation of adenosine 3', 5'-monophosphate synthesis in bacteria. I. Effect of carbon source variation on cyclic AMP synthesis in Escherichia coli B/r. 16 29

Two mutants are described in which the synthesis of tryptophanase is unusually insensitive to catabolite repression. Neither mutation is linked by transduction to the tryptophane structural gene, neither mutation renders the synthesis of beta-galactosidase insensitive to catabolite repression, and the mutations do not permit tryptophanase to be synthesized in strains deficient in adenyl cyclase. During growth in glucose-minimal medium the mutants maintained a similar intracellular concentration of cyclic AMP to their wild-type parent; but since in the wild type the concentration of cyclic AMP was the same in glycerol-minimal medium as in glucose-minimal medium, it is doubtful whether catabolite repression is mediated by measurable changes in the concentration of this nucleotide.
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PMID:Mutations in Escherichia coli that relieve catabolite repression of tryptophanase synthesis. Mutations distant from the tryptophanase gene. 17 93

From strains of Escherichia coli that carry deletions of the trp region, five different mutants were isolated that were capable of synthesizing tryptophanase at unusually high rates in conditions of severe catabolite repression. Notwithstanding the comparative insensitivity to catabolite repression, the rates of tryptophanase synthesis in the mutants were greatly diminished by the introduction of a defective gene for adenyl cyclase. Each of the mutants segregated variants of the parental type. The results of genetic analysis appear to be consistent with the mutants arose by duplication of the tryptophanase gene.
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PMID:Unstable mutations that relieve catabolite repression of tryptophanase synthesis by Escherichia coli. 32 44

Insulin on Escherichia coli was studied using wild type E. coli B/r and K12 strains and a number of phosphoenolpyruvate phosphotransferase mutants. In vivo, the effects of insulin on the differential rate of tryptophanase synthesis, the rate of alpha-methylglucoside uptake and the rate of growth on glucose were determined in E. coli B/r. In vitro, the effect of insulin on the adenylate cyclase and the phosphotransferase activities was determined using toluenized cell preparations of E. coli B/r, E. coli K12 and phosphotransferase mutant strains. The specificity of insulin action on E. coli was determined using glucagon, vasopressin and somatropin as well as insulin antisera. Results show the specific action of insulin on E. coli, inhibiting tryptophanase induction and adenylate cyclase activity, while stimulating growth on glucose and uptake and phosphorylation of alpha-methylglucoside.
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PMID:Insulin action on Escherichia coli. Regulation of the adenylate cyclase and phosphotransferase enzymes. 35 93

From a strain lacking adenyl cyclase and the catabolite-sensitive gene activator protein, two mutants were isolated that can synthesize tryptophanase. Each mutation is extremely closely linked to the tryptophanase structural gene. The mutations differ from one another in the rate of synthesis of tryptophanase that they permit in the genetic background in which they were isolated; they differ from one another and also from the wild type in the maximum rate of synthesis of tryptophanase that they permit in a genetic background with intact adenyl cyclase and catabolite-sensitive gene activator protein. Both mutations appear to lie in the tryptophanase promoter.
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PMID:Mutations in Escherichia coli that relieve catabolite repression of tryptophanase synthesis. Tryptophanase promoter-like mutations. 110 79

Acute hormonal regulation of liver carbohydrate metabolism mainly involves changes in the cytosolic levels of cAMP and Ca2+. Epinephrine, acting through beta 2-adrenergic receptors, and glucagon activate adenylate cyclase in the liver plasma membrane through a mechanism involving a guanine nucleotide-binding protein that is stimulatory to the enzyme. The resulting accumulation of cAMP leads to activation of cAMP-dependent protein kinase, which, in turn, phosphorylates many intracellular enzymes involved in the regulation of glycogen metabolism, gluconeogenesis, and glycolysis. These are (1) phosphorylase b kinase, which is activated and, in turn, phosphorylates and activates phosphorylase, the rate-limiting enzyme for glycogen breakdown; (2) glycogen synthase, which is inactivated and is rate-controlling for glycogen synthesis; (3) pyruvate kinase, which is inactivated and is an important regulatory enzyme for glycolysis; and (4) the 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase bifunctional enzyme, phosphorylation of which leads to decreased formation of fructose 2,6-P2, which is an activator of 6-phosphofructo-1-kinase and an inhibitor of fructose 1,6-bisphosphatase, both of which are important regulatory enzymes for glycolysis and gluconeogenesis. In addition to rapid effects of glucagon and beta-adrenergic agonists to increase hepatic glucose output by stimulating glycogenolysis and gluconeogenesis and inhibiting glycogen synthesis and glycolysis, these agents produce longer-term stimulatory effects on gluconeogenesis through altered synthesis of certain enzymes of gluconeogenesis/glycolysis and amino acid metabolism. For example, P-enolpyruvate carboxykinase is induced through an effect at the level of transcription mediated by cAMP-dependent protein kinase. Tyrosine amino-transferase, serine dehydratase, tryptophan oxygenase, and glucokinase are also regulated by cAMP, in part at the level of specific messenger RNA synthesis. The sympathetic nervous system and its neurohumoral agonists epinephrine and norepinephrine also rapidly alter hepatic glycogen metabolism and gluconeogenesis acting through alpha 1-adrenergic receptors. The primary response to these agonists is the phosphodiesterase-mediated breakdown of the plasma membrane polyphosphoinositide phosphatidylinositol 4,5-P2 to inositol 1,4,5-P3 and 1,2-diacylglycerol. This involves a guanine nucleotide-binding protein that is different from those involved in the regulation of adenylate cyclase. Inositol 1,4,5-P3 acts as an intracellular messenger for Ca2+ mobilization by releasing Ca2+ from the endoplasmic reticulum.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Mechanisms of hormonal regulation of hepatic glucose metabolism. 303 41

The formation of fruiting bodies in the monokaryotic fis(c) strain and a dikaryon of Coprinus macrorhizus was inhibited by growth in high-glucose media. In high-glucose media the characteristic burst of adenosine 3',5'-cyclic monophosphate (cAMP) accumulation during fruiting-body formation was absent. Enzymatic activity assays revealed that mycelia grown in high-glucose media contained relatively lower amounts of adenylate cyclase and cAMP-phosphodiesterase than mycelia grown in low-glucose media. The synthesis of inducible d-serine deaminase and tryptophanase was repressed in high-glucose media. A mutant (gluR) in which the glucose repression of fruiting-body formation is affected was isolated by selection in high-glucose media. The mutation caused the cAMP levels to be no longer affected by glucose and affected ability to synthesize the inducible d-serine deaminase and tryptophanase. The gluR mutant was partially dominant in dikaryons. It is suggested that cAMP may play important roles in inducing fruiting bodies and in controlling inducible enzyme synthesis in C. macrorhizus.
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PMID:Effect of glucose on the fruiting body formation and adenosine 3',5'-cyclic monophosphate levels in Coprinus macrorhizus. 437 Jul 68

In our previous study, an antimutagenic compound from spinach (Spinacea oleracea L.), ethoxy-substituted phylloquinone (ESP) was isolated and characterized. The current study deals with elucidation of the possible mechanism of antimutagenicity of ESP against ethyl methanesulfonate (EMS) deploying model systems such as human lymphoblast (TK+/- or TK6) cell line (thymidine kinase gene mutation assay) and Escherichia coli MG1655 (rifampicin resistance assay). Findings of the study ruled out the possibility of direct inactivation of EMS by ESP. DAPI competitive binding assay indicated the DNA minor groove binding activity of ESP. Interestingly, ESP did not display major groove binding or intercalating abilities. Further, proteomics study using 2-D gel electrophoresis in E. coli and subsequent studies involving single gene knockout strains revealed the possible role of tnaA (tryptophanase) and dgcP (diguanylate cyclase) genes in observed antimutagenicity. These genes have been reported to be involved in indole and cyclic-di-GMP biosynthesis, respectively, which eventually lead to cell division inhibition. In case of TK+/- cell line system, ADCY genes (adenylate cyclase), a functional analogue of dgcP gene, were found to be transcriptionally up-regulated. The generation/doubling time were significantly higher in E. coli or TK+/- cells treated with ESP than control cells. The findings indicated inhibition of cell proliferation by ESP through gene regulation as a possible mechanism of antimutagenicity across the biological system. Cell division inhibition actually provides additional time for the repair of damaged DNA leading to antimutagenicity.
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PMID:Molecular mechanism of antimutagenicity by an ethoxy-substituted phylloquinone (vitamin K1 derivative) from spinach (Spinacea oleracea L.). 3281 Apr 88