scholarly journals Comparative Analysis of anti-Shine- Dalgarno Function in Flavobacterium johnsoniae and Escherichia coli

2021 ◽  
Vol 8 ◽  
Author(s):  
Zakkary A. McNutt ◽  
Mai D. Gandhi ◽  
Elan A. Shatoff ◽  
Bappaditya Roy ◽  
Aishwarya Devaraj ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ribosomal Rna ◽  
Dominant Negative ◽  
Sedimentation Analysis ◽  
Complete Replacement ◽  
E Coli ◽  
Support Cell ◽  
Collective Data ◽  
Flavobacterium Johnsoniae ◽  
Reduced Activity

The anti-Shine-Dalgarno (ASD) sequence of 16S rRNA is highly conserved across Bacteria, and yet usage of Shine-Dalgarno (SD) sequences in mRNA varies dramatically, depending on the lineage. Here, we compared the effects of ASD mutagenesis in Escherichia coli, a Gammaproteobacteria which commonly employs SD sequences, and Flavobacterium johnsoniae, a Bacteroidia which rarely does. In E. coli, 30S subunits carrying any single substitution at positions 1,535–1,539 confer dominant negative phenotypes, whereas subunits with mutations at positions 1,540–1,542 are sufficient to support cell growth. These data suggest that CCUCC (1,535–1,539) represents the functional core of the element in E. coli. In F. johnsoniae, deletion of three ribosomal RNA (rrn) operons slowed growth substantially, a phenotype largely rescued by a plasmid-borne copy of the rrn operon. Using this complementation system, we found that subunits with single mutations at positions 1,535–1,537 are as active as control subunits, in sharp contrast to the E. coli results. Moreover, subunits with quadruple substitution or complete replacement of the ASD retain substantial, albeit reduced, activity. Sedimentation analysis revealed that these mutant subunits are overrepresented in the subunit fractions and underrepresented in polysome fractions, suggesting some defect in 30S biogenesis and/or translation initiation. Nonetheless, our collective data indicate that the ASD plays a much smaller role in F. johnsoniae than in E. coli, consistent with SD usage in the two organisms.

scholarly journals Etiological and Resistance Profile of Bacteria Involved in Urinary Tract Infections in Young Children

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Antonio Sorlózano-Puerto ◽  
José María Gómez-Luque ◽  
Juan de Dios Luna-del-Castillo ◽  
José María Navarro-Marí ◽  
José Gutiérrez-Fernández
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Clavulanic Acid ◽  
Total Activity ◽  
Geographic Area ◽  
E Coli ◽  
Amoxicillin Clavulanic Acid ◽  
Tract Infections ◽  
Reduced Activity

Background.The objective of this study was to identify the bacteria most frequently responsible for urinary tract infection (UTI) in the population of under-2-year-olds in our geographic area and to evaluate the activity of antibiotics widely used for UTI treatment during a 4-year study period.Materials and Methods.A retrospective analysis was conducted of data on the identification and susceptibility of microorganisms isolated in urine samples from children under 2 years of age.Results.A total of 1,045 uropathogens were isolated.Escherichia coliaccounted for the majority (60.3%) of these, followed byEnterococcus faecalis(22.4%) andKlebsiellaspp. (6.5%). The highestE. colisusceptibility rates (>90%) were to piperacillin-tazobactam, cefuroxime, cefotaxime, ceftazidime, imipenem, gentamicin, nitrofurantoin, and fosfomycin, and the lowest were to amoxicillin-clavulanic acid and cotrimoxazole. Among all bacteria isolated, we highlight the overall high activity of piperacillin-tazobactam, imipenem, nitrofurantoin, and fosfomycin against both community and hospital isolates and the reduced activity of amoxicillin-clavulanic acid, cephalosporins, gentamicin, and cotrimoxazole. There was no significant change in the total activity of any of the studied antibiotics over the 4-year study period.Conclusion.Empiric treatment with amoxicillin-clavulanic acid, cotrimoxazole, cephalosporins, and gentamicin may be inadequate due to their limited activity against uropathogens in our setting.

scholarly journals Characterization of rapidly labelled ribonucleic acid in Escherichia coli by deoxyribonucleic acid–ribonucleic acid hybridization

1968 ◽  
Vol 110 (2) ◽  
pp. 251-263 ◽  
Author(s):  
G. H. Pigott ◽  
J. E. M. Midgley
Keyword(s):  
Escherichia Coli ◽  
Ribosomal Rna ◽  
Ribonucleic Acid ◽  
Messenger Rna ◽  
Rna Binding ◽  
Hybridization Technique ◽  
E Coli ◽  
K 12 ◽  
Dna 2

1. Rapidly labelled RNA from Escherichia coli K 12 was characterized by hybridization to denatured E. coli DNA on cellulose nitrate membrane filters. The experiments were designed to show that, if sufficient denatured DNA is offered in a single challenge, practically all the rapidly labelled RNA will hybridize. With the technique employed, 75–80% hybridization efficiency could be obtained as a maximum. Even if an excess of DNA sites were offered, this value could not be improved upon in any single challenge of rapidly labelled RNA with denatured E. coli DNA. 2. It was confirmed that the hybridization technique can separate the rapidly labelled RNA into two fractions. One of these (30% of the total) was efficiently hybridized with the low DNA/RNA ratio (10:1, w/w) used in tests. The other fraction (70% of the total) was hybridized to DNA at low efficiencies with the DNA/RNA ratio 10:1, and was hybridized progressively more effectively as the amount of denatured DNA was increased. A practical maximum of 80% hybridization of all the rapidly labelled RNA was first achieved at a DNA/RNA ratio 210:1 (±10:1). This fraction was fully representative of the rapidly labelled RNA with regard to kind and relative amount of materials hybridized. 3. In competition experiments, where additions were made of unlabelled RNA prepared from E. coli DNA, DNA-dependent RNA polymerase (EC 2.7.7.6) and nucleoside 5′-triphosphates, the rapidly labelled RNA fraction hybridized at a low (10:1) DNA/RNA ratio was shown to be competitive with a product from genes other than those responsible for ribosomal RNA synthesis and thus was presumably messenger RNA. At higher DNA/rapidly labelled RNA ratios (200:1), competition with added unlabelled E. coli ribosomal RNA (without messenger RNA contaminants) lowered the hybridization of the rapidly labelled RNA from its 80% maximum to 23%. This proportion of rapidly labelled RNA was not competitive with E. coli ribosomal RNA even when the latter was in large excess. The ribosomal RNA would also not compete with the 23% rapidly labelled RNA bound to DNA at low DNA/RNA ratios. It was thus demonstrated that the major part of E. coli rapidly labelled RNA (70%) is ribosomal RNA, presumably a precursor to the RNA in mature ribosomes. 4. These studies have shown that, when earlier workers used low DNA/RNA ratios (about 10:1) in the assay of messenger RNA in bacterial rapidly labelled RNA, a reasonable estimate of this fraction was achieved. Criticisms that individual messenger RNA species may be synthesized from single DNA sites in E. coli at rates that lead to low efficiencies of messenger RNA binding at low DNA/RNA ratios are refuted. In accordance with earlier results, estimations of the messenger RNA content of E. coli in both rapidly labelled and randomly labelled RNA show that this fraction is 1·8–1·9% of the total RNA. This shows that, if any messenger RNA of relatively long life exists in E. coli, it does not contribute a measurable weight to that of rapidly labelled messenger RNA.

scholarly journals Enteropathogenic Escherichia coli Activates Ezrin, Which Participates in Disruption of Tight Junction Barrier Function

2001 ◽  
Vol 69 (9) ◽  
pp. 5679-5688 ◽  
Author(s):  
Ivana Simonovic ◽  
Monique Arpin ◽  
Athanasia Koutsouris ◽  
Holly J. Falk-Krzesinski ◽  
Gail Hecht
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Cytoskeletal Proteins ◽  
Dominant Negative ◽  
Intestinal Epithelial ◽  
E Coli ◽  
Membrane Cytoskeleton ◽  
Intestinal Pathogen ◽  
Response Expression

ABSTRACT Enteropathogenic Escherichia coli (EPEC) is an important human intestinal pathogen, especially in infants. EPEC adherence to intestinal epithelial cells induces the accumulation of a number of cytoskeletal proteins beneath the bacteria, including the membrane-cytoskeleton linker ezrin. Evidence suggests that ezrin can participate in signal transduction. The aim of this study was to determine whether ezrin is activated following EPEC infection and if it is involved in the cross talk with host intestinal epithelial cells. We show here that following EPEC attachment to intestinal epithelial cells there was significant phosphorylation of ezrin, first on threonine and later on tyrosine residues. A significant increase in cytoskeleton-associated ezrin occurred following phosphorylation, suggesting activation of this molecule. Nonpathogenic E. coli and EPEC strains harboring mutations in type III secretion failed to elicit this response. Expression of dominant-negative ezrin significantly decreased the EPEC-elicited association of ezrin with the cytoskeleton and attenuated the disruption of intestinal epithelial tight junctions. These results suggest that ezrin is involved in transducing EPEC-initiated signals that ultimately affect host physiological functions.

scholarly journals The eefABC Multidrug Efflux Pump Operon Is Repressed by H-NS in Enterobacter aerogenes

2005 ◽  
Vol 187 (11) ◽  
pp. 3894-3897 ◽  
Author(s):  
Muriel Masi ◽  
Jean-Marie Pagès ◽  
Claude Villard ◽  
Elizabeth Pradel
Keyword(s):  
Escherichia Coli ◽  
Efflux Pump ◽  
Enterobacter Aerogenes ◽  
Dominant Negative ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
E Coli ◽  
Laboratory Conditions ◽  
Wide Range

ABSTRACT The Enterobacter aerogenes eefABC locus, which encodes a tripartite efflux pump, was cloned by complementation of an Escherichia coli tolC mutant. E. aerogenes ΔacrA expressing EefABC became less susceptible to a wide range of antibiotics. Data from eef::lacZ fusions showed that eefABC was not transcribed in the various laboratory conditions tested. However, increased transcription from Peef was observed in an E. coli hns mutant. In addition, EefA was detected in E. aerogenes expressing a dominant negative E. coli hns allele.

scholarly journals Mutant Analysis Shows that Alanine Racemases from Pseudomonas aeruginosa and Escherichia coli Are Dimeric

2002 ◽  
Vol 184 (15) ◽  
pp. 4321-4325 ◽  
Author(s):  
Ulrich Strych ◽  
Michael J. Benedik
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Bacterial Growth ◽  
Dominant Negative ◽  
Double Mutation ◽  
Present Evidence ◽  
Mutant Analysis ◽  
E Coli

ABSTRACT Alanine racemases are ubiquitous prokaryotic enzymes providing the essential peptidoglycan precursor d-alanine. We present evidence that the enzymes from Pseudomonas aeruginosa and Escherichia coli function exclusively as homodimers. Moreover, we demonstrate that expression of a K35A Y235A double mutation of dadX in E. coli suppresses bacterial growth in a dominant negative fashion.

scholarly journals A COMPARATIVE ELECTRON MICROSCOPICAL STUDY OF RNA FROM DIFFERENT SOURCES

1961 ◽  
Vol 9 (2) ◽  
pp. 253-261 ◽  
Author(s):  
D. Danon ◽  
Y. Marikovsky ◽  
U. Z. Littauer
Keyword(s):  
Escherichia Coli ◽  
Molecular Weight ◽  
Aqueous Solutions ◽  
Ribosomal Rna ◽  
Ammonium Acetate ◽  
Microscopical Study ◽  
E Coli ◽  
Electron Microscopical ◽  
Different Sources ◽  
Comparative Electron

Electron micrographs of ribosomal RNA from Escherichia coli, microsomal RNA from calf, rat, and chick liver, Bacillus cereus RNA and E. coli soluble RNA are presented. Filaments of about 10 A in diameter could be observed in preparations obtained from aqueous solutions of high molecular weight RNA. When ammonium acetate solutions were used a tendency for coiling and aggregation was observed. E. coli soluble RNA appears as small, sometimes elongated particles the smallest diameter being of about 10 A.

scholarly journals The universally conserved GTPase HflX is an RNA helicase that restores heat-damaged Escherichia coli ribosomes

2018 ◽  
Vol 217 (7) ◽  
pp. 2519-2529 ◽  
Author(s):  
Sandip Dey ◽  
Chiranjit Biswas ◽  
Jayati Sengupta
Keyword(s):  
Escherichia Coli ◽  
Heat Stress ◽  
Ribosomal Rna ◽  
Large Subunit ◽  
Ribosomal Subunit ◽  
Rna Helicase ◽  
E Coli ◽  
Cryo Electron Microscopy ◽  
Guanosine Triphosphatase

The ribosome-associated GTPase HflX acts as an antiassociation factor upon binding to the 50S ribosomal subunit during heat stress in Escherichia coli. Although HflX is recognized as a guanosine triphosphatase, several studies have shown that the N-terminal domain 1 of HflX is capable of hydrolyzing adenosine triphosphate (ATP), but the functional role of its adenosine triphosphatase (ATPase) activity remains unknown. We demonstrate that E. coli HflX possesses ATP-dependent RNA helicase activity and is capable of unwinding large subunit ribosomal RNA. A cryo–electron microscopy structure of the 50S–HflX complex in the presence of nonhydrolyzable analogues of ATP and guanosine triphosphate hints at a mode of action for the RNA helicase and suggests the linker helical domain may have a determinant role in RNA unwinding. Heat stress results in inactivation of the ribosome, and we show that HflX can restore heat-damaged ribosomes and improve cell survival.

scholarly journals Graphene-Assisted Sensor for Rapid Detection of Antibiotic Resistance in Escherichia coli

2021 ◽  
Vol 9 ◽  
Author(s):  
Chunlei Li ◽  
Feng Sun
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Environmental Pollutant ◽  
Resistant Bacteria ◽  
Electrocatalytic Reduction ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Drug Resistant Bacteria ◽  
The Difference ◽  
Reduced Activity

In recent years, antibiotic-resistant bacteria caused by antibiotic abuse in the medical industry have become a new environmental pollutant that endangers public health. Therefore, it is necessary to establish a detection method for evaluating drug-resistant bacteria. In this work, we used Escherichia coli as a target model and proposed a method to evaluate its drug resistance for three antibiotics. Graphene dispersion was used to co-mix with E. coli cells for the purpose of increasing the current signal. This electrochemical-based sensor allows the evaluation of the activity of E. coli on the electrode surface. When antibiotics were present, the electrocatalytic reduction signal was diminished because of the reduced activity of E. coli. Based on the difference in the electrochemical reduction signal, we can evaluate the antibiotic resistance of different E. coli strains.

Effect of pH and Water Hardness on the Sanitizing Activity of Five Commercial lodophors

1985 ◽  
Vol 48 (7) ◽  
pp. 558-561 ◽  
Author(s):  
DALE L. FREDELL ◽  
BRUCE B. CORDS ◽  
BERTHA J. GIVINS
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Food Industry ◽  
Water Hardness ◽  
Hard Water ◽  
Effect Of Ph ◽  
E Coli ◽  
Reduced Activity

The effect of increasing pH (4 to 10) on the sanitizing activity of iodophors was measured by the Association of Official Analytical Chemists' Germicidal Detergent Sanitizers Method against four organisms of importance to the food industry. These organisms were Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella cholerasuis. Also, the effect of 250 ppm (as CaCO3) water hardness on iodophor activity was measured. In general, sanitizing efficacy was reduced at pH levels above pH 8.0. This reduced activity was more evident in hard water. Of the four orgnaisms tested, S. cholerasuis was least resistant and E. coli was most resistant to the action of iodophors.

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