scholarly journals Crystal structure of the multiple antibiotic resistance regulator MarR fromClostridium difficile

2017 ◽  
Vol 73 (6) ◽  
pp. 363-368
Author(s):  
J. W. Peng ◽  
H. Yuan ◽  
X. S. Tan
Keyword(s):  
Antibiotic Resistance ◽  
Structural Similarity ◽  
Soluble Form ◽  
Monoclinic Space Group ◽  
Multiple Antibiotic Resistance ◽  
Cell Parameters ◽  
E Coli ◽  
Archaeal Species ◽  
High Structural Similarity ◽  
First Time

Regulators of multiple antibiotic resistance (MarRs) are key players against toxins in prokaryotes. MarR homologues have been identified in many bacterial and archaeal species which pose daunting antibiotic resistance issues that threaten public health. The continuous prevalence ofClostridium difficileinfection (CDI) throughout the world is associated with the abuse of antibiotics, and antibiotic treatments of CDI have limited effect. In the genome ofC. difficilestrain 630, themarRgene (ID 4913953) encodes a MarR protein. Here, MarR fromC. difficile(MarRC.difficile) was subcloned and crystallized for the first time. MarRC.difficilewas successfully expressed inEscherichia coliin a soluble form and was purified to near-homogeneity (>95%) by a two-step purification protocol. The structure of MarRC.difficilehas been solved at 2.3 Å resolution. The crystal belonged to the monoclinic space groupP43212, with unit-cell parametersa=b= 66.569,c= 83.654 Å. The structure reported reveals MarRC.difficileto be a dimer, with each subunit consisting of six α-helices and three antiparallel β-hairpins. MarRC.difficileshows high structural similarity to the MarR proteins fromE. coliandStaphylococcus aureus, indicating that MarRC.difficilemight be a DNA-binding protein.

scholarly journals Constitutive soxR Mutations Contribute to Multiple-Antibiotic Resistance in Clinical Escherichia coli Isolates

2005 ◽  
Vol 49 (7) ◽  
pp. 2746-2752 ◽  
Author(s):  
Anastasia Koutsolioutsou ◽  
Samuel Peña-Llopis ◽  
Bruce Demple
Keyword(s):  
Nitric Oxide ◽  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Dna Sequences ◽  
Single Point ◽  
Constitutive Expression ◽  
Clinical Isolates ◽  
Multiple Antibiotic Resistance ◽  
E Coli ◽  
First Time

ABSTRACT The soxRS regulon of Escherichia coli and Salmonella enterica is induced by redox-cycling compounds or nitric oxide and provides resistance to superoxide-generating agents, macrophage-generated nitric oxide, antibiotics, and organic solvents. We have previously shown that constitutive expression of soxRS can contribute to quinolone resistance in clinically relevant S. enterica. In this work, we have carried out an analysis of the mechanism of constitutive soxS expression and its role in antibiotic resistance in E. coli clinical isolates. We show that constitutive soxS expression in three out of six strains was caused by single point mutations in the soxR gene. The mutant SoxR proteins contributed to the multiple-antibiotic resistance phenotypes of the clinical strains and were sufficient to confer multiple-antibiotic resistance in a fresh genetic background. In the other three clinical isolates, we observed, for the first time, that elevated soxS expression was not due to mutations in soxR. The mechanism of such increased soxS expression remains unclear. The same E. coli clinical isolates harbored polymorphic soxR and soxS DNA sequences, also seen for the first time.

scholarly journals Incidence and Characterization of Integrons, Genetic Elements Mediating Multiple-Drug Resistance, in AvianEscherichia coli

1999 ◽  
Vol 43 (12) ◽  
pp. 2925-2929 ◽  
Author(s):  
Lydia Bass ◽  
Cynthia A. Liebert ◽  
Margie D. Lee ◽  
Anne O. Summers ◽  
David G. White ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Gene ◽  
Multiple Drug Resistance ◽  
Marker Gene ◽  
Clinical Isolates ◽  
Multiple Antibiotic Resistance ◽  
Class 1 Integron ◽  
E Coli ◽  
Class 1

ABSTRACT Antibiotic resistance among avian bacterial isolates is common and is of great concern to the poultry industry. Approximately 36% (n = 100) of avian, pathogenic Escherichia coli isolates obtained from diseased poultry exhibited multiple-antibiotic resistance to tetracycline, oxytetracycline, streptomycin, sulfonamides, and gentamicin. Clinical avian E. coli isolates were further screened for the presence of markers for class 1 integrons, the integron recombinase intI1 and the quaternary ammonium resistance gene qacEΔ1, in order to determine the contribution of integrons to the observed multiple-antibiotic resistance phenotypes. Sixty-three percent of the clinical isolates were positive for the class 1 integron markersintI1 and qacEΔ1. PCR analysis with the conserved class 1 integron primers yielded amplicons of approximately 1 kb from E. coli isolates positive for intI1 andqacEΔ1. These PCR amplicons contained the spectinomycin-streptomycin resistance gene aadA1. Further characterization of the identified integrons revealed that many were part of the transposon Tn21, a genetic element that encodes both antibiotic resistance and heavy-metal resistance to mercuric compounds. Fifty percent of the clinical isolates positive for the integron marker gene intI1 as well as for theqacEΔ1 and aadA1 cassettes also contained the mercury reductase gene merA. The correlation between the presence of the merA gene with that of the integrase and antibiotic resistance genes suggests that these integrons are located in Tn21. The presence of these elements among avianE. coli isolates of diverse genetic makeup as well as inSalmonella suggests the mobility of Tn21 among pathogens in humans as well as poultry.

scholarly journals Detection of numerous verotoxigenic E. coli serotypes, with multiple antibiotic resistance from cattle faeces and soil

2009 ◽  
Vol 134 (3-4) ◽  
pp. 288-293 ◽  
Author(s):  
L SCOTT ◽  
P MCGEE ◽  
C WALSH ◽  
S FANNING ◽  
T SWEENEY ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Multiple Antibiotic Resistance ◽  
E Coli ◽  
Cattle Faeces

AN ANALYSIS OF THE THZ FREQUENCY SIGNATURES IN THE CELLULAR COMPONENTS OF BIOLOGICAL AGENTS

2007 ◽  
Vol 17 (02) ◽  
pp. 225-237 ◽  
Author(s):  
ALEXEI BYKHOVSKI ◽  
TATIANA GLOBUS ◽  
TATYANA KHROMOVA ◽  
BORIS GELMONT ◽  
DWIGHT WOOLARD
Keyword(s):  
Molecular Structure ◽  
Structural Similarity ◽  
Md Simulations ◽  
Detection Capability ◽  
Dna Structures ◽  
E Coli ◽  
Cellular Components ◽  
First Time ◽  
Insight Into ◽  
Specific Contribution

The development of an effective biological (bio) agent detection capability based upon terahertz (THz) frequency absorption spectra will require insight into how the constituent cellular components contribute to the overall THz signature. In this work, the specific contribution of ribonucleic acid (RNA) to THz spectra is analyzed in detail. Previously, it has only been possible to simulate partial fragments of the RNA (or DNA) structures due to the excessive computational demands. For the first time, the molecular structure of the entire transfer RNA (tRNA) molecule of E. coli was simulated and the associated THz signature was derived theoretically. The tRNA that binds amino acid tyrosine (tRNAtyr) was studied. Here, the molecular structure was optimized using the potential energy minimization and molecular dynamical (MD) simulations. Solvation effects (water molecules) were also included explicitly in the MD simulations. To verify that realistic molecular signatures were simulated, a parallel experimental study of tRNAs of E. coli was also conducted. Two very similar molecules, valine and tyrosine tRNA were investigated experimentally. Samples were prepared in the form of water solutions with the concentrations in the range 0.01-1 mg/ml. A strong correlation of the measured THz signatures associated with valine tRNA and tyrosine tRNA was observed. These findings are consistent with the structural similarity of the two tRNAs. The calculated THz signature of the tyrosine tRNA of E. coli reproduces many features of our measured spectra, and, therefore, provides valuable new insights into bio-agent detection.

scholarly journals Inhibition of the multiple antibiotic resistance (mar) operon in Escherichia coli by antisense DNA analogs.

1997 ◽  
Vol 41 (12) ◽  
pp. 2699-2704 ◽  
Author(s):  
D G White ◽  
K Maneewannakul ◽  
E von Hofe ◽  
M Zillman ◽  
W Eisenberg ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Antisense Oligonucleotides ◽  
Multiple Antibiotic Resistance ◽  
Wild Type ◽  
Lacz Expression ◽  
E Coli ◽  
Plasmid Construct ◽  
Dna Analogs ◽  
Susceptibility And Resistance

The multiple antibiotic resistance operon (marORAB) in Escherichia coli controls intrinsic susceptibility and resistance to multiple, structurally different antibiotics and other noxious agents. A plasmid construct with marA cloned in the antisense direction reduced LacZ expression from a constitutively expressed marA::lacZ translational fusion and inhibited the induced expression of LacZ in cells bearing the wild-type repressed fusion. The marA antisense construction also decreased the multiple antibiotic resistance of a Mar mutant. Two antisense phosphorothioate oligonucleotides, one targeted to marO and the other targeted to marA of the mar operon, introduced by heat shock or electroporation reduced LacZ expression in the strain having the marA::lacZ fusion. One antisense oligonucleotide, tested against a Mar mutant of E. coli ML308-225, increased the bactericidal activity of norfloxacin. These studies demonstrate the efficacy of exogenously delivered antisense oligonucleotides targeted to the marRAB operon in inhibiting expression of this chromosomal regulatory locus.

Commentary: Dissemination of a Plasmid Determining Multiple Antibiotic Resistance Between Two Veterans Administration Medical Centers

1986 ◽  
Vol 7 (7) ◽  
pp. 362-364 ◽  
Author(s):  
David M. Shlaes ◽  
Charlotte Currie-McCumber
Keyword(s):  
Antibiotic Resistance ◽  
Restriction Endonuclease ◽  
Veterans Administration ◽  
Restriction Endonuclease Digestion ◽  
Multiple Antibiotic Resistance ◽  
Administration Medical ◽  
E Coli ◽  
Medical Centers ◽  
R Plasmids ◽  
Endonuclease Digestion

AbstractThe endemic R-plasmids mediating resistance to gentamicin and multiple other antibiotics among many species of Enterobacteriaceae from the Minneapolis and Cleveland Veterans Administration Medical Centers were compared by restriction endonuclease digestion profiling and by phenotype expressed in sensitive E. coli recipients. Southern hybridizations were also performed. Our data indicate that these plasmids demonstrate some microheterogeneity, but are very closely related. Both are self-transferable and mediate resistance to ampicillin, carbenicillin, chloramphenicol, gentamicin, tobramycin, neomycin and kanamycin. These results suggest the dissemination of a conjugal R-plasmid or of Enterobacteriaceae bearing the plasmid between two midwestern Veterans Administration Medical Centers. The most likely mechanism of transmission may be the frequent transfer of patients between midwestern Veterans Administration Medical Centers.

scholarly journals Extended Spectrum Beta Lactamases Detection and Multiple Antibiotic Resistance Indexing of Escherichia Coli from Urine Samples of Patients from a Referral Hospital of Eastern Nepal

2015 ◽  
Vol 3 (3) ◽  
pp. 423-426 ◽  
Author(s):  
A. Chakrawarti ◽  
P. Dongol ◽  
H. Khanal ◽  
P. Subba ◽  
J.J. Benerjee
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Urine Samples ◽  
Multiple Antibiotic Resistance ◽  
Beta Lactamases ◽  
E Coli ◽  
Extended Spectrum Beta Lactamases ◽  
Mar Index ◽  
Esbl Producers ◽  
Disc Assay

Background: Escherichia coli is the most common causative agent of urinary tract infection. Antibiotic resistance among uropathogens has become a prominent public health problem. Multidrug resistance bacteria have limited the therapeutic possibilities by producing Extended Spectrum Beta Lactamases (ESBL). Objective: Since routine monitoring of ESBL producers are not conducted in clinical laboratories their true prevalence is still unknown. So the objective of this research was to assess multiple antibiotic resistance (MAR) indices and determine ESBL production among Escherichia coli isolated from urine samples. Methods: Standard microbiological techniques and antibiotic sensitivity test were performed by Kirby Bauer disc diffusion method to identify E. coli. ESBL screening was done by using Ceftriaxone, Aztreonam, Cefotaxime, Ceftazidime and Cefpodoxime whereas confirmation by combined disc assay. SPSS 16 software was used to analyze data. Results: 86.95% E. coli isolates were MDR strains. 27 isolates had multiple antibiotic resistance (MAR) index of 0.2 and 5 isolates had MAR index of 0.7. E. coli isolates showed higher degree of resistance towards Amoxicillin (100%) while 100% were sensitive towards Gentamicin followed by Nitrofurantoin (62.31%). The reliable screening agent for ESBL detection with sensitivity 100% and positive predictive value of 80% was Cefotaxime. Combined disc assay detected 12/69 (17.31%) of E. coli isolates as confirmed ESBL producers. Conclusion: The ubiquity of ESBL-producing E. coli was observed emphasizing the necessity of regular surveillance of ESBL producing clinical isolates in clinical samples to minimize multi-drug resistance strains and avert the ineffectiveness of antimicrobial agent for good health practices.\Int J Appl Sci Biotechnol, Vol 3(3): 423-426

scholarly journals Crystal structure of gluconate 5-dehydrogenase from Lentibacter algarum

2020 ◽  
Vol 76 (5) ◽  
pp. 228-234
Author(s):  
Dengke Tian ◽  
Xueqi Fu ◽  
Wenqiang Cao ◽  
Hong Yuan
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Structural Similarity ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
Space Group ◽  
Cell Parameters ◽  
High Structural Similarity

Gluconate 5-dehydrogenase (Ga5DH; EC 1.1.1.69) from Lentibacter algarum (LaGa5DH) was recombinantly expressed in Escherichia coli and purified to homogeneity. The protein was crystallized and the crystal structure was solved at 2.1 Å resolution. The crystal belonged to the monoclinic system, with space group P1 and unit-cell parameters a = 55.42, b = 55.48, c = 79.16 Å, α = 100.51, β = 105.66, γ = 97.99°. The structure revealed LaGaDH to be a tetramer, with each subunit consisting of six α-helices and three antiparallel β-hairpins. LaGa5DH has high structural similarity to other Ga5DH proteins, demonstrating that this enzyme is highly conserved.

scholarly journals Multi-Enzymatic Cascades in the Synthesis of Modified Nucleosides: Comparison of the Thermophilic and Mesophilic Pathways

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 586
Author(s):  
Ilja V. Fateev ◽  
Maria A. Kostromina ◽  
Yuliya A. Abramchik ◽  
Barbara Z. Eletskaya ◽  
Olga O. Mikheeva ◽  
...  
Keyword(s):  
Small Difference ◽  
Thermus Thermophilus ◽  
Cascade Reactions ◽  
Product Formation ◽  
Modified Nucleosides ◽  
Soluble Form ◽  
Chromatographic Purification ◽  
E Coli ◽  
Enzymatic Cascades ◽  
First Time

A comparative study of the possibilities of using ribokinase → phosphopentomutase → nucleoside phosphorylase cascades in the synthesis of modified nucleosides was carried out. Recombinant phosphopentomutase from Thermus thermophilus HB27 was obtained for the first time: a strain producing a soluble form of the enzyme was created, and a method for its isolation and chromatographic purification was developed. It was shown that cascade syntheses of modified nucleosides can be carried out both by the mesophilic and thermophilic routes from D-pentoses: ribose, 2-deoxyribose, arabinose, xylose, and 2-deoxy-2-fluoroarabinose. The efficiency of 2-chloradenine nucleoside synthesis decreases in the following order: Rib (92), dRib (74), Ara (66), F-Ara (8), and Xyl (2%) in 30 min for mesophilic enzymes. For thermophilic enzymes: Rib (76), dRib (62), Ara (32), F-Ara (<1), and Xyl (2%) in 30 min. Upon incubation of the reaction mixtures for a day, the amounts of 2-chloroadenine riboside (thermophilic cascade), 2-deoxyribosides (both cascades), and arabinoside (mesophilic cascade) decreased roughly by half. The conversion of the base to 2-fluoroarabinosides and xylosides continued to increase in both cases and reached 20-40%. Four nucleosides were quantitatively produced by a cascade of enzymes from D-ribose and D-arabinose. The ribosides of 8-azaguanine (thermophilic cascade) and allopurinol (mesophilic cascade) were synthesized. For the first time, D-arabinosides of 2-chloro-6-methoxypurine and 2-fluoro-6-methoxypurine were synthesized using the mesophilic cascade. Despite the relatively small difference in temperatures when performing the cascade reactions (50 and 80 °C), the rate of product formation in the reactions with Escherichia coli enzymes was significantly higher. E. coli enzymes also provided a higher content of the target products in the reaction mixture. Therefore, they are more appropriate for use in the polyenzymatic synthesis of modified nucleosides.

scholarly journals Isolation, Identification and Antibiotic Susceptibility of Escherichia coli Isolated from Raw Meat from Modake and Ile-Ife, Osun State, Nigeria

2021 ◽  
pp. 9-13
Author(s):  
Wilkie Eunice Damilola ◽  
Oluduro Anthonia Olufunke ◽  
Ezeani Chidinma Vivian ◽  
Sotala Toyosi Teniola
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Antibiotic Susceptibility ◽  
Multiple Antibiotic Resistance ◽  
Raw Meat ◽  
E Coli ◽  
Antibiotic Susceptibility Test ◽  
Mueller Hinton Agar ◽  
Meat Samples ◽  
High Level

The study reported isolation, identification and antibiotic susceptibility of Escherichia coli isolated from raw meat from Modakeke and Ile-ife, Osun State, Nigeria, with the view to determining the antibiogram profiling of the bacterial isolates.  In this study, five samples of fresh meat were collected from different abattoirs in Ile-Ife and Modakeke, Osun State. Isolates of Escherichia coli were isolated, identified morphologically based on their growth on nutrient agar and subjected to antibiotic susceptibility test on Mueller Hinton agar. The mean microbial load from the meat samples ranged from 8.85 x 102cfu/ml to 5.77 x 104cfu/ml. A total of 69 E. coli isolates were recovered from the meat sampled. All the isolates appeared cream, translucent, entire, convex, circular, smooth and glistering. The isolates were identified as Gram negative rods, non-motile, lactose fermenters, positive for indole test and negative for citrate utilization test. All the E. coli isolates were resistant to augmentin, ceftriazone, nitrofurantoin and gentamycin. 98.55% of E. coli isolated was resistant to amoxillin and the least resistant was recorded in ofloxacin (8.70%). However, 91.30% of the E. coli isolates was sensitive to ofloxacin, 81.16% to ciprofloxacin and 36.23% to pefloxacin while none was sensitive to augmentin, ceftriazone, nitrofurantoin and gentamycin. A total of 19 different multiple antibiotic resistance patterns were observed among the isolates. Thirty isolates (43.48%) showed multiple antibiotic resistance to 5 and 10 different antibiotic types each. The study concluded that occurrence of E. coli infection is high in the study area with high level of multiple antibiotic resistance.

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