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

1971 ◽  
Vol 122 (2) ◽  
pp. 219-224 ◽  
Author(s):  
M. Aboud ◽  
M. Burger
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Cyclic Amp ◽  
Direct Effect ◽  
Ribonucleic Acid ◽  
Catabolite Repression ◽  
Mrna Accumulation ◽  
Messenger Ribonucleic Acid ◽  
K 12 ◽  
Specific Mrna

When Escherichia coli K-12 Hfr.H was induced to synthesize β-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.

scholarly journals Correlation between Growth Rates, EIIACrr Phosphorylation, and Intracellular Cyclic AMP Levels in Escherichia coli K-12

2007 ◽  
Vol 189 (19) ◽  
pp. 6891-6900 ◽  
Author(s):  
Katja Bettenbrock ◽  
Thomas Sauter ◽  
Knut Jahreis ◽  
Andreas Kremling ◽  
Joseph W. Lengeler ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cyclic Amp ◽  
Growth Rates ◽  
Catabolite Repression ◽  
Cellular Growth ◽  
Receptor Protein ◽  
Intracellular Camp ◽  
Global Control ◽  
K 12

ABSTRACT In Escherichia coli K-12, components of the phosphoenolpyruvate-dependent phosphotransferase systems (PTSs) represent a signal transduction system involved in the global control of carbon catabolism through inducer exclusion mediated by phosphoenolpyruvate-dependent protein kinase enzyme IIACrr (EIIACrr) (= EIIAGlc) and catabolite repression mediated by the global regulator cyclic AMP (cAMP)-cAMP receptor protein (CRP). We measured in a systematic way the relation between cellular growth rates and the key parameters of catabolite repression, i.e., the phosphorylated EIIACrr (EIIACrr∼P) level and the cAMP level, using in vitro and in vivo assays. Different growth rates were obtained by using either various carbon sources or by growing the cells with limited concentrations of glucose, sucrose, and mannitol in continuous bioreactor experiments. The ratio of EIIACrr to EIIACrr∼P and the intracellular cAMP concentrations, deduced from the activity of a cAMP-CRP-dependent promoter, correlated well with specific growth rates between 0.3 h−1 and 0.7 h−1, corresponding to generation times of about 138 and 60 min, respectively. Below and above this range, these parameters were increasingly uncoupled from the growth rate, which perhaps indicates an increasing role executed by other global control systems, in particular the stringent-relaxed response system.

scholarly journals Catabolite Repression Control of napF (Periplasmic Nitrate Reductase) Operon Expression in Escherichia coli K-12

2008 ◽  
Vol 191 (3) ◽  
pp. 996-1005 ◽  
Author(s):  
Valley Stewart ◽  
Peggy J. Bledsoe ◽  
Li-Ling Chen ◽  
Amie Cai
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Nitrate Reductase ◽  
Catabolite Repression ◽  
Carbon Sources ◽  
Anaerobic Growth ◽  
Periplasmic Nitrate Reductase ◽  
Membrane Bound ◽  
Operon Expression ◽  
K 12

ABSTRACT Escherichia coli, a facultative aerobe, expresses two distinct respiratory nitrate reductases. The periplasmic NapABC enzyme likely functions during growth in nitrate-limited environments, whereas the membrane-bound NarGHI enzyme functions during growth in nitrate-rich environments. Maximal expression of the napFDAGHBC operon encoding periplasmic nitrate reductase results from synergistic transcription activation by the Fnr and phospho-NarP proteins, acting in response to anaerobiosis and nitrate or nitrite, respectively. Here, we report that, during anaerobic growth with no added nitrate, less-preferred carbon sources stimulated napF operon expression by as much as fourfold relative to glucose. Deletion analysis identified a cyclic AMP receptor protein (Crp) binding site upstream of the NarP and Fnr sites as being required for this stimulation. The napD and nrfA operon control regions from Shewanella spp. also have apparent Crp and Fnr sites, and expression from the Shewanella oneidensis nrfA control region cloned in E. coli was subject to catabolite repression. In contrast, the carbon source had relatively little effect on expression of the narGHJI operon encoding membrane-bound nitrate reductase under any growth condition tested. Carbon source oxidation state had no influence on synthesis of either nitrate reductase. The results suggest that the Fnr and Crp proteins may act synergistically to enhance NapABC synthesis during growth with poor carbon sources to help obtain energy from low levels of nitrate.

scholarly journals Galactose-specific messenger ribonucleic acid contents in Escherichia coli

1971 ◽  
Vol 121 (1) ◽  
pp. 109-116 ◽  
Author(s):  
J. R. Gosden ◽  
M. I. Irving ◽  
J. O. Bishop
Keyword(s):  
Escherichia Coli ◽  
Ribonucleic Acid ◽  
Gene Frequency ◽  
Wild Type ◽  
Total Rna ◽  
Messenger Ribonucleic Acid ◽  
E Coli ◽  
Escherichia Coli K12 ◽  
Different Cultures ◽  
Specific Mrna

A method is described for measuring the proportion of galactose-specific mRNA (gal-mRNA) in the total RNA extracted from pulse-labelled cells of Escherichia coli K12, by DNA–RNA hybridization with DNA prepared from bacteriophage λdg. RNA from wild-type E. coli was compared with RNA from a homogenote carrying the gal operon both in the chromosome and in a substituted sex-factor, and with RNA from a deletion strain that carried the galactose operon only in the exogenote. In each case the cultures were induced with fucose. Under these conditions the amount of gal-mRNA was found to be proportional to the content of galactokinase in the different cultures, and to the gene frequency. The amounts of gal-mRNA in an Oc mutant and an R− mutant were also proportional to the observed contents of galactokinase. In cultures repressed for the enzymes of the galactose operon with thiomethylgalactoside, the content of gal-mRNA was higher than expected from the content of galactokinase. Possible explanations of this finding are discussed.

Sign in / Sign up

Export Citation Format

Share Document