Increase in the Stability of Serine Acetyltransferase from Escherichia coli against Cold Inactivation and Proteolysis by Forming a Bienzyme Complex.

The effect of disulfide and sulfhydryl reagents on the rate of abortive and productive elongation has been studied using Escherichia coli RNA polymerase holoenzyme and poly[d(A-T)] as template. In the presence of UTP as a single substrate and UpA as a primer, the enzyme catalyzed efficiently the synthesis of the trinucleotide product UpApU. Incubation of RNA polymerase with 1 mM 2-mercaptoethanol resulted in a 5-fold increase of the rate of UpApU synthesis. In contrast, incubation of the enzyme with 1 mM 5,5'-dithio-bis(2-nitrobenzoic) acid resulted in a 6-fold decrease of the rate of abortive elongation. Determination of the steady state kinetic constants associated with UpApU synthesis disclosed that the disulfide and sulfhydryl reagents mainly affected the rate of UpApU release from the ternary transcription complexes and therefore influenced the stability of such complexes.

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In Vitro and In Vivo Assessment of the Potential of Escherichia coli Phages to Treat Infections and Survive Gastric Conditions

Microorganisms ◽

10.3390/microorganisms9091869 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1869

Author(s):

Joanna Kaczorowska ◽

Eoghan Casey ◽

Gabriele A. Lugli ◽

Marco Ventura ◽

David J. Clarke ◽

...

Keyword(s):

Escherichia Coli ◽

Galleria Mellonella ◽

Enterotoxigenic Escherichia Coli ◽

E Coli ◽

Composite Mixture ◽

Ph Conditions ◽

The Stability ◽

Higher Sensitivity

Enterotoxigenic Escherichia coli (ETEC) and Shigella ssp. infections are associated with high rates of mortality, especially in infants in developing countries. Due to increasing levels of global antibiotic resistance exhibited by many pathogenic organisms, alternative strategies to combat such infections are urgently required. In this study, we evaluated the stability of five coliphages (four Myoviridae and one Siphoviridae phage) over a range of pH conditions and in simulated gastric conditions. The Myoviridae phages were stable across the range of pH 2 to 7, while the Siphoviridae phage, JK16, exhibited higher sensitivity to low pH. A composite mixture of these five phages was tested in vivo in a Galleria mellonella model. The obtained data clearly shows potential in treating E. coli infections prophylactically.

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Interaction specificity between the chaperone and proteolytic components of the cyanobacterial Clp protease

Biochemical Journal ◽

10.1042/bj20120649 ◽

2012 ◽

Vol 446 (2) ◽

pp. 311-320 ◽

Cited By ~ 14

Author(s):

Anders Tryggvesson ◽

Frida M. Ståhlberg ◽

Axel Mogk ◽

Kornelius Zeth ◽

Adrian K. Clarke

Keyword(s):

Escherichia Coli ◽

Active Sites ◽

Terminal Sequence ◽

Core Complex ◽

Clp Protease ◽

E Coli ◽

Loop Region ◽

N Terminus ◽

Specific Association ◽

The Stability

The Clp protease is conserved among eubacteria and most eukaryotes, and uses ATP to drive protein substrate unfolding and translocation into a chamber of sequestered proteolytic active sites. In plant chloroplasts and cyanobacteria, the essential constitutive Clp protease consists of the Hsp100/ClpC chaperone partnering a proteolytic core of catalytic ClpP and noncatalytic ClpR subunits. In the present study, we have examined putative determinants conferring the highly specific association between ClpC and the ClpP3/R core from the model cyanobacterium Synechococcus elongatus. Two conserved sequences in the N-terminus of ClpR (tyrosine and proline motifs) and one in the N-terminus of ClpP3 (MPIG motif) were identified as being crucial for the ClpC–ClpP3/R association. These N-terminal domains also influence the stability of the ClpP3/R core complex itself. A unique C-terminal sequence was also found in plant and cyanobacterial ClpC orthologues just downstream of the P-loop region previously shown in Escherichia coli to be important for Hsp100 association to ClpP. This R motif in Synechococcus ClpC confers specificity for the ClpP3/R core and prevents association with E. coli ClpP; its removal from ClpC reverses this core specificity.

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Critical Concentration of Lecithin Enhances the Antimicrobial Activity of Eugenol against Escherichia coli

Applied and Environmental Microbiology ◽

10.1128/aem.03467-16 ◽

2017 ◽

Vol 83 (8) ◽

Cited By ~ 6

Author(s):

Haoshu Zhang ◽

Edward G. Dudley ◽

P. Michael Davidson ◽

Federico Harte

Keyword(s):

Escherichia Coli ◽

Essential Oils ◽

Food Systems ◽

Critical Concentration ◽

Physical Stability ◽

Antimicrobial Properties ◽

Content Type ◽

Antimicrobial Effects ◽

Wide Range ◽

The Stability

ABSTRACT Lecithin is a natural emulsifier used in a wide range of food and nonfood applications to improve physical stability, with no known bioactive effects. In this study, the effect of lecithin on the antimicrobial performance of a constant eugenol concentration was tested against three Escherichia coli strains (C600, 0.1229, and O157:H7 strain ATCC 700728). This is the first study, to our knowledge, focusing on lecithin at concentrations below those commonly used in foods to improve the stability of oil in water emulsions (≤10 mg/100 ml). For all three cultures, significant synergistic antimicrobial effects were observed when E. coli cultures were exposed to a constant eugenol concentration (ranging from 0.043 to 0.050% [wt/wt]) together with critical lecithin concentrations ranging from 0.5 to 1 mg/100 ml. Increasing the concentration of lecithin above 1 mg/100 ml (up to 10 mg/100 ml lecithin) diminished the antibacterial effect to values similar to those with eugenol-only treatments. The formation of aggregates (<100 nm) at the critical lecithin concentration was observed using cryo-transmission electron microscopy (cryo-TEM), together with a reduction in light absorbance at 284 nm. At critically low concentrations of lecithin, the formation of nanoscale aggregates is responsible for improving eugenol antimicrobial effects. IMPORTANCE Essential oils (EOs) are effective natural antimicrobials. However, their hydrophobicity and strong aromatic character limit the use of essential oils in food systems. Emulsifiers (e.g., lecithin) increase the stability of EOs in water-based systems but fail to consistently improve antimicrobial effects. We demonstrate that lecithin, within a narrow critical concentration window, can enhance the antimicrobial properties of eugenol. This study highlights the potential bioactivity of lecithin when utilized to effectively control foodborne pathogens.

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The Effect of a Cytidine-to-Uridine Transition on the Stability of Escherichia coli A19 5-S RNA

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1982.tb06904.x ◽

2005 ◽

Vol 127 (3) ◽

pp. 531-537 ◽

Cited By ~ 10

Author(s):

Martin DIGWEED ◽

Izumi KUMAGAI ◽

Tomas PIELER ◽

Volker A. ERDMANN

Keyword(s):

Escherichia Coli ◽

The Stability

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Effects of lyophilization on the stability of bacteriophages against different serogroups of Shiga toxin-producing Escherichia coli

Cryobiology ◽

10.1016/j.cryobiol.2020.07.012 ◽

2020 ◽

Vol 96 ◽

pp. 85-91

Author(s):

Valerie M. Lavenburg ◽

Yen-Te Liao ◽

Alexandra Salvador ◽

Angeline L. Hsu ◽

Leslie A. Harden ◽

...

Keyword(s):

Escherichia Coli ◽

Shiga Toxin ◽

The Stability

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Effects of zinc and other metal ions on the stability and activity of Escherichia coli alkaline phosphatase

Biochemical Journal ◽

10.1042/bj1240025 ◽

1971 ◽

Vol 124 (1) ◽

pp. 25-30 ◽

Cited By ~ 18

Author(s):

C. N. A. Trotman ◽

C. Greenwood

Keyword(s):

Escherichia Coli ◽

Alkaline Phosphatase ◽

Metal Ions ◽

Phosphatase Activity ◽

Structural Stability ◽

Zinc Content ◽

Sedimentation Velocity ◽

Reducing Agent ◽

Deficient Mutant ◽

The Stability

Measurement of the ultraviolet circular dichroism of apo-(alkaline phosphatase) in urea solutions showed substantial denaturation in 3m-urea. A zinc-deficient mutant alkaline phosphatase behaved similarly. The stability of the enzyme in 6m-urea was followed as a function of its zinc content and was found to be dependent on the first two of the four zinc atoms bound by apoenzyme. Phosphatase activity was mostly dependent on a second pair of zinc atoms. Mn2+, Co2+, Cu2+ or Cd2+ also restored structural stability. Sedimentation-velocity and -equilibrium experiments revealed that dissociation of the dimer accompanied apoenzyme denaturation in urea concentrations of 1m or higher, without treatment with disulphide-reducing agent.

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Thermotoga neapolitana Homotetrameric Xylose Isomerase Is Expressed as a Catalytically Active and Thermostable Dimer in Escherichia coli

Applied and Environmental Microbiology ◽

10.1128/aem.64.7.2357-2360.1998 ◽

1998 ◽

Vol 64 (7) ◽

pp. 2357-2360 ◽

Cited By ~ 18

Author(s):

J. Michael Hess ◽

Vladimir Tchernajenko ◽

Claire Vieille ◽

J. Gregory Zeikus ◽

Robert M. Kelly

Keyword(s):

Escherichia Coli ◽

Differential Scanning Calorimetry ◽

Gel Filtration ◽

Xylose Isomerase ◽

Thermotoga Neapolitana ◽

Thermal Transitions ◽

Scanning Calorimetry ◽

Catalytically Active ◽

The Stability ◽

Tetrameric Form

ABSTRACT The xylA gene from Thermotoga neapolitana5068 was expressed in Escherichia coli. Gel filtration chromatography showed that the recombinant enzyme was both a homodimer and a homotetramer, with the dimer being the more abundant form. The purified native enzyme, however, has been shown to be exclusively tetrameric. The two enzyme forms had comparable stabilities when they were thermoinactivated at 95°C. Differential scanning calorimetry revealed thermal transitions at 99 and 109.5°C for both forms, with an additional shoulder at 91°C for the tetramer. These results suggest that the association of the subunits into the tetrameric form may have little impact on the stability and biocatalytic properties of the enzyme.

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