L-Asparaginase production during static incubation of aerobically grown Escherichia coli B

1973 ◽  
Vol 19 (10) ◽  
pp. 1251-1257 ◽  
Author(s):  
L. D. Boeck ◽  
P. P. K. Ho
Keyword(s):  
Escherichia Coli ◽  
Cell Proliferation ◽  
Amino Acid ◽  
B Cells ◽  
Amino Acid Analysis ◽  
Enzyme Synthesis ◽  
E Coli ◽  
Low Levels ◽  
Escherichia Coli B ◽  
Aerobic Cell

Glucose, galactose, or pyruvate independently supported biosynthesis of 1.5–2.6 IU/ml of antilymphoma L-asparaginase during static incubation of aerobically grown E. coli B cells. Fructose, lactate, and other compounds did not produce enzyme levels in excess of 0.12 IU/ml. Asparaginase synthesis by cells incubated in the presence of either glucose or pyruvate was inhibited by fluoride, iodoacetate, and sulfite. Amino acid analysis of the modified trypticase soy broth (MTSB) medium, used for aerobic cell proliferation and subsequent enzyme synthesis during static incubation, permitted development of a chemically defined (CD) medium. Washed cells, grown aerobically in the MTSB medium, produced equivalent quantities of L-asparaginase in both the MTSB and CD media. Low levels of chloramphenicol or puromycin reduced enzyme synthesis by as much as 95%.

An Endonuclease for Depurinated DNA in Escherichia coli B

1972 ◽  
Vol 50 (2) ◽  
pp. 217-224 ◽  
Author(s):  
W. G. Verly ◽  
Y. Paquette
Keyword(s):  
Escherichia Coli ◽  
B Cells ◽  
Molecular Mechanism ◽  
Alkylating Agents ◽  
Repair Enzyme ◽  
E Coli ◽  
Escherichia Coli B

Escherichia coli B cells contain an endonuclease which hydrolyzes apurinic sites in DNA. The enzyme has been demonstrated in vitro by the action of E. coli B41 proteins on depurinated DNA. This endonuclease probably plays a role in the molecular mechanism of the delayed inactivation of the T7 coliphage treated by monofunctional alkylating agents, which has been shown to be dependent on depurination; this endonuclease could also be a repair enzyme necessary for the first step of the repair of DNA containing apurinic sites.

scholarly journals The 503nm pigment of Escherichia coli

1970 ◽  
Vol 120 (4) ◽  
pp. 771-775 ◽  
Author(s):  
Joyce R. Kamitakahara ◽  
W. J. Polglase
Keyword(s):  
Escherichia Coli ◽  
B Cells ◽  
Cell Protein ◽  
Wild Type ◽  
E Coli ◽  
Aerobic Energy Metabolism ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Escherichia Coli B ◽  
Wild Type Parent

The yield of cell protein was one-third less for streptomycin-dependent Escherichia coli B than for the wild-type parent strain when both were grown aerobically on a medium with limiting glucose, but anaerobically the yield of protein was similar for both strains. The transient pigment absorbing at 503nm that is known to be present in E. coli and other organisms was not detectable in streptomycin-dependent mutants nor in a non-dependent (energy-deficient) revertant. When wild-type E. coli B was grown on limiting glucose–salts medium containing 2,4 dinitrophenol, the yield of cell protein was decreased and formation of the 503nm pigment was inhibited. Fumarase, aconitase and glucose 6-phosphate dehydrogenase were de-repressed in E. coli B cells grown with excess of glucose in a medium containing 2,4-dinitrophenol. In air-oxidized, wild-type E. coli B cells, the 503nm pigment appeared before reduced cytochromes when gluconate was the substrate but failed to appear when succinate was the substrate. The results provide evidence for a role of the 503nm pigment in aerobic energy metabolism, possibly as an electron acceptor from NADPH.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

scholarly journals Amino acid sequence of the L-arabinose-binding protein from Escherichia coli B/r.

1977 ◽  
Vol 252 (14) ◽  
pp. 5135-5141 ◽  
Author(s):  
R W Hogg ◽  
M A Hermodson
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Binding Protein ◽  
Escherichia Coli B

scholarly journals Roles of the C-Terminal Amino Acids of Non-Hexameric Helicases: Insights from Escherichia coli UvrD

2021 ◽  
Vol 22 (3) ◽  
pp. 1018
Author(s):  
Hiroaki Yokota
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Single Molecule ◽  
Underlying Mechanism ◽  
Amino Acid Sequences ◽  
E Coli ◽  
X Ray Crystallography ◽  
Terminal Amino

Helicases are nucleic acid-unwinding enzymes that are involved in the maintenance of genome integrity. Several parts of the amino acid sequences of helicases are very similar, and these quite well-conserved amino acid sequences are termed “helicase motifs”. Previous studies by X-ray crystallography and single-molecule measurements have suggested a common underlying mechanism for their function. These studies indicate the role of the helicase motifs in unwinding nucleic acids. In contrast, the sequence and length of the C-terminal amino acids of helicases are highly variable. In this paper, I review past and recent studies that proposed helicase mechanisms and studies that investigated the roles of the C-terminal amino acids on helicase and dimerization activities, primarily on the non-hexermeric Escherichia coli (E. coli) UvrD helicase. Then, I center on my recent study of single-molecule direct visualization of a UvrD mutant lacking the C-terminal 40 amino acids (UvrDΔ40C) used in studies proposing the monomer helicase model. The study demonstrated that multiple UvrDΔ40C molecules jointly participated in DNA unwinding, presumably by forming an oligomer. Thus, the single-molecule observation addressed how the C-terminal amino acids affect the number of helicases bound to DNA, oligomerization, and unwinding activity, which can be applied to other helicases.

scholarly journals Escherichia coli Contamination of Vegetables Grown in Soils Fertilized with Noncomposted Bovine Manure: Garden-Scale Studies

2004 ◽  
Vol 70 (11) ◽  
pp. 6420-6427 ◽  
Author(s):  
Steven C. Ingham ◽  
Jill A. Losinski ◽  
Matthew P. Andrews ◽  
Jane E. Breuer ◽  
Jeffry R. Breuer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Tap Water ◽  
Silty Clay ◽  
Silt Loam ◽  
Silty Clay Loam ◽  
Manure Application ◽  
E Coli ◽  
Fertilized Soil ◽  
Low Levels ◽  
National Organic Program

ABSTRACT In this study we tested the validity of the National Organic Program (NOP) requirement for a ≥120-day interval between application of noncomposted manure and harvesting of vegetables grown in manure-fertilized soil. Noncomposted bovine manure was applied to 9.3-m2 plots at three Wisconsin sites (loamy sand, silt loam, and silty clay loam) prior to spring and summer planting of carrots, radishes, and lettuce. Soil and washed (30 s under running tap water) vegetables were analyzed for indigenous Escherichia coli. Within 90 days, the level of E. coli in manure-fertilized soil generally decreased by about 3 log CFU/g from initial levels of 4.2 to 4.4 log CFU/g. Low levels of E. coli generally persisted in manure-fertilized soil for more than 100 days and were detected in enriched soil from all three sites 132 to 168 days after manure application. For carrots and lettuce, at least one enrichment-negative sample was obtained ≤100 days after manure application for 63 and 88% of the treatments, respectively. The current ≥120-day limit provided an even greater likelihood of not detecting E. coli on carrots (≥1 enrichment-negative result for 100% of the treatments). The rapid maturation of radishes prevented conclusive evaluation of a 100- or 120-day application-to-harvest interval. The absolute absence of E. coli from vegetables harvested from manure-fertilized Wisconsin soils may not be ensured solely by adherence to the NOP ≥120-day limit. Unless pathogens are far better at colonizing vegetables than indigenous E. coli strains are, it appears that the risk of contamination for vegetables grown in Wisconsin soils would be elevated only slightly by reducing the NOP requirement to ≥100 days.

Expression and partial purification of human pro-opiomelanocortin in Escherichia coli

1989 ◽  
Vol 3 (2) ◽  
pp. 105-112 ◽  
Author(s):  
T. S. Grewal ◽  
P. J. Lowry ◽  
D. Savva
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Fusion Protein ◽  
Western Blot ◽  
Blot Analysis ◽  
Expression Vectors ◽  
Partial Purification ◽  
Amino Acid Residues ◽  
E Coli ◽  
Dna Fragment

ABSTRACT A large portion of the human pro-opiomelanocortin (POMC) peptide corresponding to amino acid residues 59–241 has been cloned and expressed in Escherichia coli. A 1·0 kb DNA fragment encoding this peptide was cloned into the expression vectors pUC8 and pUR291. Plasmid pJMBG51 (a pUC8 recombinant) was found to direct the expression of a 24 kDa peptide. The recombinant pUR291 (pJMBG52) was shown to produce a β-galactosidase fusion protein of 140 kDa. Western blot analysis showed that both the 24 kDa and 140 kDa peptides are recognized by antibodies raised against POMC-derived peptides. The β-galactosidase fusion protein has been partially purified from crude E. coli cell lysates using affinity chromatography on p-aminobenzyl-1-thio-β-d-galactopyranoside agarose.

Mechanism of inhibition of bacteriophage T7 DNA synthesis in Escherichia coli B cells infected by alkylated bacteriophage T7

1986 ◽  
Vol 166 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Guy Czaika ◽  
Margaret D. Mamet-Bratley ◽  
Barbara Karska-Wysocki
Keyword(s):  
Escherichia Coli ◽  
B Cells ◽  
Dna Synthesis ◽  
Bacteriophage T7 ◽  
Mechanism Of Inhibition ◽  
Escherichia Coli B

scholarly journals Mechanically Ventilated Broiler Sheds: a Possible Source of Aerosolized Salmonella, Campylobacter, and Escherichia coli

2009 ◽  
Vol 75 (23) ◽  
pp. 7417-7425 ◽  
Author(s):  
H. N. Chinivasagam ◽  
T. Tran ◽  
L. Maddock ◽  
A. Gale ◽  
P. J. Blackall
Keyword(s):  
Escherichia Coli ◽  
Most Probable Number ◽  
Production Cycle ◽  
Airborne Bacteria ◽  
Probable Number ◽  
Mechanically Ventilated ◽  
The Public ◽  
E Coli ◽  
Poultry Farms ◽  
Low Levels

ABSTRACT This study assessed the levels of two key pathogens, Salmonella and Campylobacter, along with the indicator organism Escherichia coli in aerosols within and outside poultry sheds. The study ranged over a 3-year period on four poultry farms and consisted of six trials across the boiler production cycle of around 55 days. Weekly testing of litter and aerosols was carried out through the cycle. A key point that emerged is that the levels of airborne bacteria are linked to the levels of these bacteria in litter. This hypothesis was demonstrated by E. coli. The typical levels of E. coli in litter were ∼108 CFU g−1 and, as a consequence, were in the range of 102 to 104 CFU m−3 in aerosols, both inside and outside the shed. The external levels were always lower than the internal levels. Salmonella was only present intermittently in litter and at lower levels (103 to 105 most probable number [MPN] g−1) and consequently present only intermittently and at low levels in air inside (range of 0.65 to 4.4 MPN m−3) and once outside (2.3 MPN m−3). The Salmonella serovars isolated in litter were generally also isolated from aerosols and dust, with the Salmonella serovars Chester and Sofia being the dominant serovars across these interfaces. Campylobacter was detected late in the production cycle, in litter at levels of around 107 MPN g−1. Campylobacter was detected only once inside the shed and then at low levels of 2.2 MPN m−3. Thus, the public health risk from these organisms in poultry environments via the aerosol pathway is minimal.

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