Regulation of Adaptive Enzyme Synthesis in Prokaryotes Exemplified by the Arabinose Regulon of Escherichia coli

1982 ◽  
pp. 257-279
Author(s):  
L. Nover
Keyword(s):  
Escherichia Coli ◽  
Enzyme Synthesis

THE EFFECT OF SUBLETHAL DOSES OF ARTIFICIAL SUNLIGHT ON ADAPTIVE ENZYME SYNTHESIS BY ESCHERICHIA COLI

1963 ◽  
Vol 41 (1) ◽  
pp. 859-866
Author(s):  
S. J. Webb
Keyword(s):  
Escherichia Coli ◽  
Blue Light ◽  
Red Light ◽  
Enzyme Synthesis ◽  
Blue Dye ◽  
Direct Sunlight ◽  
Yellow Light ◽  
Blue Region ◽  
Sublethal Doses ◽  
Inhibited Enzyme

The effect of sublethal doses of artificial sunlight and individual wavebands of light on the ability of Escherichia coli to synthesize the enzymes concerned in lactose oxidation have been studied. It was found that direct sunlight completely inhibited enzyme synthesis but did not affect the action of preformed enzymes. Blue and yellow light were both active in preventing enzyme synthesis but the blue region of the spectrum was by far the most effective. No effect of red light could be demonstrated. Staining cells with yellow or red dyes reduced the action of blue light whereas staining the cells with a blue dye increased the effectiveness of yellow light.

scholarly journals REGULATION OF NEWLY EVOLVED ENZYMES. IV. DIRECTED EVOLUTION OF THE EBG REPRESSOR

Genetics ◽  
1978 ◽  
Vol 90 (4) ◽  
pp. 673-681
Author(s):  
Barry G Hall
Keyword(s):  
Escherichia Coli ◽  
Directed Evolution ◽  
Enzyme Synthesis ◽  
Regulatory Function ◽  
Wild Type ◽  
Selection For ◽  
Selection Of

ABSTRACT In Escherichia coli, the wild-type repressor of ebg (evolved β-galactosidase) enzyme synthesis, specified by the ebgR  + gene, responds very weakly to lactulose (fructose-β-D-galactopyranoside). Selection for a functional repressor that responds strongly to lactulose as an inducer reveals the existence of ebgR+L mutants, which occur spontaneously at a frequency of about 2 x 10-10. ebgR+L mutants are pleiotropic in that they specify ebg repressor with a greatly increased response to lactulose, lactose, galactose-arabinoside and methyl-galactoside as inducers. Selection of ebgR+L mutants is discussed within the framework of directed evolution of a regulatory function.

scholarly journals Biosynthesis in vitro of tryptophanase by polyribosomes from induced cultures of Escherichia coli

1971 ◽  
Vol 123 (3) ◽  
pp. 355-365 ◽  
Author(s):  
S. A. M. Khairul Bashar ◽  
J. H. Parish ◽  
Marjorie Brown
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Enzyme Activity ◽  
Amino Acid ◽  
Enzyme Synthesis ◽  
Supernatant Fraction ◽  
Amino Acid Residues ◽  
Radioactive Amino Acid ◽  
Tryptophanase Activity

1. Polyribosomes were isolated from Escherichia coli grown in media in which tryptophanase is induced and in which it is repressed. The polyribosomes from the induced bacteria had a small amount of tryptophanase activity associated with them. 2. A portion of the enzyme activity remained bound to polyribosomes during centrifuging in sucrose gradients. 3. Incubation of tryptophanase-containing polyribosomes with puromycin released enzyme activity. 4. The binding of the enzyme to the polyribosomes did not depend on the presence of DNA. 5. When the polyribosomes were incubated under conditions of protein synthesis with supernatant fraction obtained from repressed bacteria, a small but statistically significant increase in enzyme activity was produced. 6. When a radioactive amino acid was included in the incubation mixture for the tryptophanase system a radioactive protein was obtained whose chromatographic, electrophoretic and sedimentation properties were identical with those of tryptophanase. 7. The amount of incorporation was consistent with the amount of new enzyme synthesis predicted by the increase in enzyme activity. Both radioactive incorporation and increase in enzyme activity were shown to be energy-dependent and also negative controls were obtained by using zero-time incubations or polyribosomes isolated from either repressed cells or a mutant lacking the ability to produce tryptophanase. 8. The distribution of radioactive leucine in the carboxyl region of the newly labelled tryptophanase was examined by digesting the labelled protein with carboxypeptidases. It was shown that the radioactivity was more highly concentrated towards the carboxyl terminus when the incubation times for protein synthesis were shorter (implying that, with longer incubation times, longer lengths of polypeptide chain contained radioactive amino acid residues).

FACTORS AFFECTING THE VIABILITY OF AIR-BORNE BACTERIA: V. THE EFFECT OF DESICCATION ON SOME METABOLIC SYSTEMS OF ESCHERICHIA COLP

1961 ◽  
Vol 7 (4) ◽  
pp. 621-632 ◽  
Author(s):  
S. J. Webb
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Glucose Oxidation ◽  
Cell Metabolism ◽  
Enzyme Synthesis ◽  
Acid Oxidation ◽  
Factors Affecting ◽  
Amino Acid Oxidation ◽  
Metabolic Systems ◽  
Absorbing Material

The effect of desiccation on the ability of Escherichia coli to carry out oxidations, decarboxylations, and adaptive enzyme synthesis has been studied. Changes in cell metabolism due to drying were studied; and also the influence on such changes of protecting the cells with inositol. Dehydration brought about the release of 260-mμ absorbing material from the cell, the amount released being increased in the presence of inositol. Dehydration reduced amino acid oxidation and increased decarboxylation and glucose oxidation. Protecting the cells against death with inositol not only failed to prevent these changes but, with the exception of glucose oxidation, made them more pronounced. The synthesis of adaptive β-galactosidase was found to be greatly inhibited by desiccation and this inhibition could be prevented by inositol. It is suggested that a structural change in the nucleoproteins concerned in protein synthesis is responsible for the death of dried cells rather than damage to their membrane.

Repression of inducible enzyme synthesis in a mutant of Escherichia coli K12 deleted for the ptsH gene

1977 ◽  
Vol 153 (2) ◽  
pp. 185-190 ◽  
Author(s):  
Vladimir N. Gershanovitch ◽  
Tamilla S. Ilvina ◽  
Olga Y. Rusina ◽  
Natalya V. Yourovitskaya ◽  
Tatyana N. Bolshakova
Keyword(s):  
Escherichia Coli ◽  
Enzyme Synthesis ◽  
Escherichia Coli K12 ◽  
Inducible Enzyme
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