scholarly journals KINETICS OF F TRANSFER AND RECOMBINANT PRODUCTION IN F + x F- MATINGS IN ESCHERICHIA COLI K-12

Genetics ◽  
1969 ◽  
Vol 63 (1) ◽  
pp. 39-52
Author(s):  
Roy Curtiss ◽  
Janet Renshaw
Keyword(s):  
Escherichia Coli ◽  
Recombinant Production ◽  
K 12 ◽  
Kinetics Of

scholarly journals Strain improvement of Escherichia coli K-12 for recombinant production of deuterated proteins

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Vinardas Kelpšas ◽  
Claes von Wachenfeldt
Keyword(s):  
Escherichia Coli ◽  
Structural Biology ◽  
Strain Improvement ◽  
Growth Media ◽  
Genomic Changes ◽  
E Coli ◽  
Recombinant Production ◽  
High Concentrations ◽  
Neutron Protein Crystallography ◽  
K 12

AbstractDeuterium isotope labelling is important for structural biology methods such as neutron protein crystallography, nuclear magnetic resonance and small angle neutron scattering studies of proteins. Deuterium is a natural low abundance stable hydrogen isotope that in high concentrations negatively affect growth of cells. The generation time for Escherichia coli K-12 in deuterated medium is substantially increased compared to cells grown in hydrogenated (protiated) medium. By using a mutagenesis plasmid based approach we have isolated an E. coli strain derived from E. coli K-12 substrain MG1655 that show increased fitness in deuterium based growth media, without general adaptation to media components. By whole-genome sequencing we identified the genomic changes in the obtained strain and show that it can be used for recombinant production of perdeuterated proteins in amounts typically needed for structural biology studies.

scholarly journals Kinetics of methylation in Escherichia coli K-12.

1984 ◽  
Vol 159 (1) ◽  
pp. 421-423 ◽  
Author(s):  
S M Lyons ◽  
P F Schendel
Keyword(s):  
Escherichia Coli ◽  
K 12 ◽  
Kinetics Of

KINETICS OF THREONINE DEAMINASE OF ESCHERICHIA COLI K-12 AND A STREPTOMYCIN-DEPENDENT MUTANT

1967 ◽  
Vol 45 (1) ◽  
pp. 1-10 ◽  
Author(s):  
I. D. Desai ◽  
W. J. Polglase
Keyword(s):  
Escherichia Coli ◽  
Selective Advantage ◽  
Kinetic Properties ◽  
Wild Type ◽  
Threonine Deaminase ◽  
E Coli ◽  
Type K ◽  
Hyperbolic Curve ◽  
K 12 ◽  
Kinetics Of

The relation between threonine deaminase activity and threonine concentration in sonic extracts of wild-type and streptomycin-dependent Escherichia coli K-12 was found to follow a hyperbolic curve. A similar relationship was obtained between enzyme activity and pyridoxal concentration. However, when serine was used as substrate, the activity–concentration curve was sigmoid, suggesting that serine may be a weaker effector of allosteric transition than threonine. The kinetic properties of the (derepressed) threonine deaminase of streptomycin-dependent E. coli K-12 were found to be similar to those of the enzyme of the wild-type K-12.It is postulated that derepression of threonine deaminase in streptomycin-dependent E. coli K-12 provides a selective advantage which permits exponential growth of this mutant in the presence of L-valine, which is an excretory product of streptomycin-dependent microorganisms.

scholarly journals KINETICS OF GENETIC RECOMBINATION IN ESCHERICHIA COLI K-12: COMPETITION BETWEEN GENETIC INTEGRATION AND DEGRADATION

Genetics ◽  
1973 ◽  
Vol 75 (4) ◽  
pp. 579-592
Author(s):  
Jonathan T Ou ◽  
Thomas H Wood
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Genetic Recombination ◽  
Physiological State ◽  
Rich Medium ◽  
Inhibiting Protein ◽  
Time Required ◽  
K 12 ◽  
Kinetics Of ◽  
Genetic Integration

ABSTRACT The effect of shifting zygotes from a rich medium into a poor medium (shift-down) on the frequency of recombination has been examined; our results suggest that protein syntheses other than those required for growth may be involved. Experiments with chloramphenicol support this notion, and further suggest that there is a competition between genetic integration and degradation in the recipient cells. By inhibiting protein synthesis one can shift the competition in favor of either integration or segregation, depending on the physiological state of the zygotes. By calculating the time required for segregation as one generation, we conclude that the recombination chromosome is homozygous at the time of integration.

scholarly journals Autoinducer 3 and Epinephrine Signaling in the Kinetics of Locus of Enterocyte Effacement Gene Expression in Enterohemorrhagic Escherichia coli

2006 ◽  
Vol 74 (10) ◽  
pp. 5445-5455 ◽  
Author(s):  
Matthew Walters ◽  
Vanessa Sperandio
Keyword(s):  
Escherichia Coli ◽  
Quorum Sensing ◽  
Enterohemorrhagic Escherichia Coli ◽  
Exponential Growth Phase ◽  
Wild Type ◽  
Protein Levels ◽  
Enterocyte Effacement ◽  
K 12 ◽  
And Function ◽  
Kinetics Of

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is responsible for causing outbreaks of bloody diarrhea and hemolytic-uremic syndrome throughout the world. The locus of enterocyte effacement (LEE) consists of five major operons and is required for the formation of attaching and effacing lesions that disrupt intestinal epithelial microvilli. We have previously reported that expression of EHEC LEE genes is regulated by the luxS quorum-sensing system. The luxS gene in EHEC affects the production of autoinducer 3 (AI-3), which activates the LEE. Epinephrine and norepinephrine also activate the LEE in a manner similar to that of AI-3. Previous studies of quorum-sensing regulation of LEE transcription have thus far been restricted to using reporter systems in an E. coli K-12 background. Here, we examined the kinetics of LEE gene transcription, protein expression, and function of the LEE type III secretion apparatus in wild-type (WT) EHEC and an isogenic luxS mutant. The results revealed that the luxS mutant had diminished transcription from the LEE promoters during the mid-exponential growth phase; decreased protein levels of EscJ, Tir, and EspA; and reduced secretion of EspA and EspB. The luxS mutation also caused a delay in the formation of attaching and effacing lesions on cultured epithelial cells compared to the wild type. Epinephrine enhanced LEE expression in both the WT and the luxS mutant, but the WT still exhibited greater LEE activation. The results suggest a possible synergistic relationship between AI-3 and epinephrine. The combined effects of these two signaling molecules may lead to greater LEE expression and a more efficient infection.

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