scholarly journals The control of ribonucleic acid synthesis in bacteria. Polymerization rates for ribonucleic acids in amino acid-starved relaxed and stringent auxotrophs of Escherichia coli

1972 ◽  
Vol 128 (5) ◽  
pp. 1021-1031 ◽  
Author(s):  
W. J. H. Gray ◽  
T. G. Vickers ◽  
J. E. M. Midgley
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Normal Growth ◽  
Acid Synthesis ◽  
Amino Acid Deprivation ◽  
Ribonucleic Acids ◽  
Rate Of Polymerization ◽  
Chain Polymerization ◽  
Multiple Amino Acid ◽  
Nucleotide Bases

Polymerization rates of newly formed chains of various RNA fractions were measured in Escherichia coli CP78 (RCstr) and CP79 (RCrel) multiple amino acid auxotrophs, deprived of four amino acids essential for growth. Immediately after the onset of severe amino acid deprivation, in RCstr strains the rate of labelling of RNA by exogenous nucleotide bases was greatly diminished. At first, the initiation of new RNA chains declined faster than the rate of polymerization in RCstr organisms, but as starvation proceeded the rate of polymerization was eventually lowered to about 10% of that found during normal growth. In strain CP79 (RCrel), on the other hand, chain-polymerization rates were unaffected by amino acid withdrawal. Artificial depletion of the intracellular purine nucleotide pools in RCstr or RCrel strains by trimethoprim, before the onset of amino acid deprivation, showed that in the RCstr, but not the RCrel strain, amino acid withdrawal gave rise to an inability of the cells to utilize exogenously supplied purine or pyrimidine bases for RNA synthesis. During a prolonged starvation, the observed 100-fold decrease in the total rate of incorporation of exogenous nucleotide bases into the RNA of RCstr organisms was ascribed to a combination of a tenfold decrease in the overall rate of RNA chain polymerization, at least a fivefold decrease in the ability of the cells to utilize exogenous bases and a preferential inhibition of initiation of stable RNA chains. None of these changes occurred in the corresponding RCrel strain.

scholarly journals The control of ribonucleic acid synthesis in bacteria. The synthesis and stability of ribonucleic acids in relaxed and stringent amino acid auxotrophs of Escherichia coli

1972 ◽  
Vol 128 (5) ◽  
pp. 1007-1020 ◽  
Author(s):  
W. J. H. Gray ◽  
J. E. M. Midgley
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Heterogeneous Material ◽  
Acid Synthesis ◽  
Sucrose Density Gradient ◽  
23S Rrna ◽  
Ribonucleic Acids ◽  
Mrna Content ◽  
High Concentrations ◽  
The Stability

The biosynthesis and stability of various RNA fractions was studied in RCstr and RCrel multiple amino acid auxotrophs of Escherichia coli. In conditions of amino acid deprivation, RCstr mutants were labelled with exogenous nucleotide bases at less than 1% of the rate found in cultures growing normally in supplemented media. Studies by DNA–RNA hybridization and by other methods showed that, during a period of amino acid withdrawal, not more than 60–70% of the labelled RNA formed in RCstr mutants had the characteristics of mRNA. Evidence was obtained for some degradation of newly formed 16S and 23S rRNA species to heterogeneous material of lower molecular weight. This led to overestimations of the mRNA content of rapidly labelled RNA from such methods as simple examination of sucrose-density-gradient profiles. In RCrel strains the absolute and relative rates of synthesis of the various RNA fractions were not greatly affected. However, the stability of about half of the mRNA fraction was increased in RCrel strains during amino acid starvation, giving kinetics of mRNA labelling and turnover that were identical with those found in either RCstr or RCrel strains inhibited by high concentrations of chloramphenicol. Coincidence hybridization techniques showed that the mRNA content of amino acid-starved RCstr auxotrophs was unchanged from that found in normally growing cells. In contrast, RCrel strains deprived of amino acids increased their mRNA content about threefold. In such cultures the mRNA content of accumulating newly formed RNA was a constant 16% by wt.

scholarly journals Early changes in the messenger ribonucleic acid concentration of amino acid-starved cells of Escherichia coli are not dependent on the state of the rel gene

1974 ◽  
Vol 144 (3) ◽  
pp. 605-606
Author(s):  
John E. M. Midgley ◽  
R. John Smith
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Acid Concentration ◽  
Ribonucleic Acid ◽  
The State ◽  
Amino Acid Deprivation ◽  
Messenger Ribonucleic Acid

Measurements of the concentration of mRNA in rel+and rel-strains of Escherichia coli shortly after the imposition of amino acid deprivation indicate that there is a temporary fall in the amount of this fraction relative to the total cellular RNA.

scholarly journals Anaerobic Cysteine Degradation and Potential Metabolic Coordination in Salmonella enterica and Escherichia coli

2017 ◽  
Vol 199 (16) ◽  
Author(s):  
Melissa Loddeke ◽  
Barbara Schneider ◽  
Tamiko Oguri ◽  
Iti Mehta ◽  
Zhenyu Xuan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Salmonella Enterica ◽  
Acid Synthesis ◽  
Lower Growth ◽  
Amino Acid Synthesis ◽  
Content Type ◽  
E Coli ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

ABSTRACT Salmonella enterica has two CyuR-activated enzymes that degrade cysteine, i.e., the aerobic CdsH and an unidentified anaerobic enzyme; Escherichia coli has only the latter. To identify the anaerobic enzyme, transcript profiling was performed for E. coli without cyuR and with overexpressed cyuR. Thirty-seven genes showed at least 5-fold changes in expression, and the cyuPA (formerly yhaOM) operon showed the greatest difference. Homology suggested that CyuP and CyuA represent a cysteine transporter and an iron-sulfur-containing cysteine desulfidase, respectively. E. coli and S. enterica ΔcyuA mutants grown with cysteine generated substantially less sulfide and had lower growth yields. Oxygen affected the CyuR-dependent genes reciprocally; cyuP-lacZ expression was greater anaerobically, whereas cdsH-lacZ expression was greater aerobically. In E. coli and S. enterica, anaerobic cyuP expression required cyuR and cysteine and was induced by l-cysteine, d-cysteine, and a few sulfur-containing compounds. Loss of either CyuA or RidA, both of which contribute to cysteine degradation to pyruvate, increased cyuP-lacZ expression, which suggests that CyuA modulates intracellular cysteine concentrations. Phylogenetic analysis showed that CyuA homologs are present in obligate and facultative anaerobes, confirming an anaerobic function, and in archaeal methanogens and bacterial acetogens, suggesting an ancient origin. Our results show that CyuA is the major anaerobic cysteine-catabolizing enzyme in both E. coli and S. enterica, and it is proposed that anaerobic cysteine catabolism can contribute to coordination of sulfur assimilation and amino acid synthesis. IMPORTANCE Sulfur-containing compounds such as cysteine and sulfide are essential and reactive metabolites. Exogenous sulfur-containing compounds can alter the thiol landscape and intracellular redox reactions and are known to affect several cellular processes, including swarming motility, antibiotic sensitivity, and biofilm formation. Cysteine inhibits several enzymes of amino acid synthesis; therefore, increasing cysteine concentrations could increase the levels of the inhibited enzymes. This inhibition implies that control of intracellular cysteine levels, which is the immediate product of sulfide assimilation, can affect several pathways and coordinate metabolism. For these and other reasons, cysteine and sulfide concentrations must be controlled, and this work shows that cysteine catabolism contributes to this control.

The influence of radiomimetic substances on deoxyribonucleic acid synthesis and function studied in escherichia coli/phage systems - IV. Colony-forming ability and escherichia coli strain B and two of its mutants following alkylation

1959 ◽  
Vol 151 (942) ◽  
pp. 129-147 ◽  
Keyword(s):  
Escherichia Coli ◽  
Chemical Reactivity ◽  
Alkylating Agents ◽  
Chemical Change ◽  
Acid Synthesis ◽  
Coli Strain ◽  
Ribonucleic Acids ◽  
Significant Difference ◽  
Synthetic Capacity ◽  
And Function

Escherichia coli strain B , its mutant B/r and a new mutant, designated B/HN 2, have been employed in a study of the effect of alkylating agents upon the survival of colony-forming ability and phage-synthetic capacity. This has been done against the background of our earlier work upon phage and that of other workers upon bacteria, employing both alkylating agents and radiations. The sensitivity of B toward all the compounds now studied was greater than that of the other two strains as regards colony-forming ability, whereas all three strains showed a similar sensitivity in regard to capacity. Survival curves of all strains treated with monofunctional agents were of a so-called ‘multi-hit’ type, whereas those for bifunctional compounds were downwardly concave. The response to di(2-ehloroethyl) methylamine ( HN 2) was complicated by the chemical change undergone by this substance in aqueous solution, as was shown by a comparison of fresh and aged solutions and of the effect of different cultural conditions prior to treatment. As with radiations, phage-synthetic capacity was considerably less sensitive to alkylation than colony-forming ability, whilst this sensitivity was essentially the same for the three strains. No significant difference was found between the effect of HN 2 on the capacity of B for T 2 and for T 7. The capacity of B/r for T 2 was more sensitive to treatment by a bifunctional agent than by a monofunctional agent of similar chemical reactivity. It is suggested that this may implicate ribonucleic acids as the reactive substrate essential to capacity.

Inhibition of uridine 5′-diphosphate-N-acetylmuramyl-L-alanine synthetase by β-chloro-L-alanine in Escherichia coli

1982 ◽  
Vol 28 (6) ◽  
pp. 654-659 ◽  
Author(s):  
Edward E. Ishiguro
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Diaminopimelic Acid ◽  
Alanine Racemase ◽  
Uridine Diphosphate ◽  
Amino Acid Deprivation ◽  
Intact Cells ◽  
Low Concentration ◽  
Low Concentrations ◽  
Precursor Synthesis

The synthesis of the nucleotide precursors for peptidoglycan is regulated by the relA gene in Escherichia coli. Thus, nucleotide precursors labeled with [3H]diaminopimelic acid accumulated in a relA strain but not in an isogenic relA+ strain during amino acid deprivation. Furthermore, nucleotide precursor synthesis was relaxed in the amino acid deprived relA+ strain by treatment with chloramphenicol. Uridine diphosphate-N-acetylmuramyl-pentapeptide (UDP-MurNAc-pentapeptide) was the major component accumulated during the relaxed synthesis of nucleotide precursors in both relA+ and relA strains. The effect of β-chloro-L-alanine (CLA) on the relaxed synthesis of nucleotide precursors for peptidoglycan was determined. At a low concentration (0.0625 mM) CLA inhibited the synthesis of UDP-MurNAc-pentapeptide and caused the accumulation of UDP-MurNAc-tripeptide. Thus, low concentrations of CLA probably inhibited alanine racemase, as reported previously. Higher concentrations of CLA also inhibited an earlier step in nucleotide precursor synthesis. This was shown to be due to the inhibition of UDP-MurNAc-L-alanine synthetase by CLA. CLA inhibited the activity of this enzyme in cell-free extracts as well as in intact cells.

Sign in / Sign up

Export Citation Format

Share Document