scholarly journals Constitutive and repressivle enzymes of the common pathway of aromatic biosynthesis in Escherichia coli K-12: regulation of enzyme synthesis at different growth rates.

1976 ◽  
Vol 127 (3) ◽  
pp. 1085-1097 ◽  
Author(s):  
D E Tribe ◽  
H Camakaris ◽  
J Pittard
Keyword(s):  
Escherichia Coli ◽  
Growth Rates ◽  
Enzyme Synthesis ◽  
Common Pathway ◽  
Aromatic Biosynthesis ◽  
The Common ◽  
K 12 ◽  
Regulation Of Enzyme Synthesis

scholarly journals Adaptation in a Mouse Colony Monoassociated with Escherichia coli K-12 for More than 1,000 Days

2010 ◽  
Vol 76 (14) ◽  
pp. 4655-4663 ◽  
Author(s):  
Sean M. Lee ◽  
Aaron Wyse ◽  
Aaron Lesher ◽  
Mary Lou Everett ◽  
Linda Lou ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Rates ◽  
Bacterial Species ◽  
Intestinal Flora ◽  
Average Density ◽  
Host Bacterium ◽  
E Coli ◽  
K 12

ABSTRACT Although mice associated with a single bacterial species have been used to provide a simple model for analysis of host-bacteria relationships, bacteria have been shown to display adaptability when grown in a variety of novel environments. In this study, changes associated with the host-bacterium relationship in mice monoassociated with Escherichia coli K-12 over a period of 1,031 days were evaluated. After 80 days, phenotypic diversification of E. coli was observed, with the colonizing bacteria having a broader distribution of growth rates in the laboratory than the parent E. coli. After 1,031 days, which included three generations of mice and an estimated 20,000 generations of E. coli, the initially homogeneous bacteria colonizing the mice had evolved to have widely different growth rates on agar, a potential decrease in tendency for spontaneous lysis in vivo, and an increased tendency for spontaneous lysis in vitro. Importantly, mice at the end of the experiment were colonized at an average density of bacteria that was more than 3-fold greater than mice colonized on day 80. Evaluation of selected isolates on day 1,031 revealed unique restriction endonuclease patterns and differences between isolates in expression of more than 10% of the proteins identified by two-dimensional electrophoresis, suggesting complex changes underlying the evolution of diversity during the experiment. These results suggest that monoassociated mice might be used as a tool for characterizing niches occupied by the intestinal flora and potentially as a method of targeting the evolution of bacteria for applications in biotechnology.

scholarly journals Positive Growth Rate-Dependent Regulation of the pdxA, ksgA, and pdxB Genes of Escherichia coli K-12

2002 ◽  
Vol 184 (5) ◽  
pp. 1359-1369 ◽  
Author(s):  
Andrew J. Pease ◽  
Benjamin R. Roa ◽  
Wen Luo ◽  
Malcolm E. Winkler
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Protein Accumulation ◽  
Rate Regulation ◽  
Specific Transcript ◽  
Positive Growth ◽  
Positive Growth Rate ◽  
K 12 ◽  
Per Gene

ABSTRACT We found that transcription of the pdxA and pdxB genes, which mediate steps in the biosynthesis of the essential coenzyme pyridoxal 5"-phosphate, and the ksgA gene, which encodes an rRNA modification enzyme and is partly cotranscribed with pdxA, is subject to positive growth rate regulation in Escherichia coli K-12. The amounts of the pdxA-ksgA cotranscript and pdxB- and ksgA-specific transcripts and expression from pdxA- and pdxB-lacZ fusions increased as the growth rate increased. The half-lives of ksgA- and pdxB-specific transcripts were not affected by the growth rate, whereas the half-life of the pdxA-ksgA cotranscript was too short to be measured accurately. A method of normalization was applied to determine the amount of mRNA synthesized per gene and the rate of protein accumulation per gene. Normalization removed an apparent anomaly at fast growth rates and demonstrated that positive regulation of pdxB occurs at the level of transcription initiation over the whole range of growth rates tested. RNA polymerase limitation and autoregulation could not account for the positive growth rate regulation of pdxA, pdxB, and ksgA transcription. On the other hand, growth rate regulation of the amount of the pdxA-ksgA cotranscript was abolished by a fis mutation, suggesting a role for the Fis protein. In contrast, the fis mutation had no effect on pdxB- or ksgA-specific transcript amounts. The amounts of the pdxA-ksgA cotranscript and ksgA-specific transcript were repressed in the presence of high intracellular concentrations of guanosine tetraphosphate; however, this effect was independent of relA function for the pdxA-ksgA cotranscript. Amounts of the pdxB-specific transcript remained unchanged during amino acid starvation in wild-type and relA mutant strains.

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.

Transient regulation of enzyme synthesis in Escherichia coli

1973 ◽  
Vol 121 (1) ◽  
pp. 77-81 ◽  
Author(s):  
E. Boy ◽  
J. Theze ◽  
J. C. Patte
Keyword(s):  
Escherichia Coli ◽  
Enzyme Synthesis ◽  
Regulation Of Enzyme Synthesis

scholarly journals Initiation and Velocity of Chromosome Replication in Escherichia coli B/r and K-12

1998 ◽  
Vol 180 (2) ◽  
pp. 265-273 ◽  
Author(s):  
Meeshel Bipatnath ◽  
Patrick P. Dennis ◽  
Hans Bremer
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Cell Mass ◽  
Chromosome Replication ◽  
Chromosomal Replication ◽  
Copy Numbers ◽  
Identical Manner ◽  
Time Required ◽  
K 12

ABSTRACT The macromolecular composition and a number of parameters affecting chromosome replication were examined over a range of exponential growth rates in two common Escherichia coli strains, B/r and K-12 AB1157. Based on improved measurements of DNA after treatment of exponential cultures with rifampin, the cell mass per chromosomal replication origin (initiation mass) and the time required to replicate the chromosome from origin to terminus (C period) were determined. For these two strains, the initiation mass approached values of 8 × 10−10 and 10 × 10−10 units of optical density (at 460 nm) of culture mass per oriC, respectively, at growth rates above 1 doubling/h (at 37°C). The amount of protein per oriC decreased with increasing growth rate for AB1157 and remained nearly constant for the B/r strain. The C period decreased for both strains in an essentially identical manner from about 70 min at 0.6 doublings/h to about 33 min at 3 doublings/h. From the initiation mass andC period, relative or absolute copy numbers for genes with known map locations can be accurately determined at different growth rates. At growth rates above 2 doublings/h, when chromosomes are highly branched, genes near the origin are about threefold more prevalent than genes near the terminus. At a growth rate of 0.6 doubling/h, this ratio is only about 1.7, which reflects the lower degree of chromosome branching.

scholarly journals Distribution of Core Oligosaccharide Types in Lipopolysaccharides from Escherichia coli

2000 ◽  
Vol 68 (3) ◽  
pp. 1116-1124 ◽  
Author(s):  
Karen Amor ◽  
David E. Heinrichs ◽  
Emilisa Frirdich ◽  
Kim Ziebell ◽  
Roger P. Johnson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Core Oligosaccharide ◽  
Phylogenetic Groups ◽  
E Coli ◽  
Biosynthesis Gene ◽  
Group A ◽  
The Common ◽  
K 12 ◽  
Group D

ABSTRACT In the lipopolysaccharides of Escherichia coli there are five distinct core oligosaccharide (core OS) structures, designated K-12 and R1 to R4. The objective of this work was to determine the prevalences of these core OS types within the species. Unique sequences in the waa (core OS biosynthesis) gene operon were used to develop a PCR-based system that facilitated unequivocal determination of the core OS types in isolates of E. coli. This system was applied to the 72 isolates in the E. coli ECOR collection, a compilation of isolates that is considered to be broadly representative of the genetic diversity of the species. Fifty (69.4%) of the ECOR isolates contained the R1 core OS, 8 (11.1%) were representatives of R2, 8 (11.1%) were R3, 2 (2.8%) were R4, and only 4 (5.6%) were K-12. R1 is the only core OS type found in all four major phylogenetic groups (A, B1, B2, and D) in the ECOR collection. Virulent extraintestinal pathogenic E. coli isolates tend to be closely related to group B2 and, to a lesser extent, group D isolates. All of the ECOR representatives from the B2 and D groups had the R1 core OS. In contrast, commensal E. coli isolates are more closely related to group A, which contains isolates representing each of the five core OS structures. R3 was the only core OS type found in 38 verotoxigenic E. coli (VTEC) isolates from humans and cattle belonging to the common enterohemorrhagic E. coliserogroups O157, O111, and O26. Although isolates from other VTEC serogroups showed more core OS diversity, the R3 type (83.1% of all VTEC isolates) was still predominant. When non-VTEC commensal isolates from cattle were analyzed, it was found that most possessed the R1 core OS type.

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