scholarly journals Characterization of high-level fluoroquinolone resistance in Escherichia coli O78:K80 isolated from turkeys

2001 ◽  
Vol 47 (3) ◽  
pp. 341-343 ◽  
Author(s):  
E. Giraud
Keyword(s):  
Escherichia Coli ◽  
Fluoroquinolone Resistance ◽  
High Level

scholarly journals Contributions of individual mechanisms to fluoroquinolone resistance in 36 Escherichia coli strains isolated from humans and animals.

1996 ◽  
Vol 40 (10) ◽  
pp. 2380-2386 ◽  
Author(s):  
M J Everett ◽  
Y F Jin ◽  
V Ricci ◽  
L J Piddock
Keyword(s):  
Escherichia Coli ◽  
Dna Sequences ◽  
Quinolone Resistance ◽  
Fluoroquinolone Resistance ◽  
Polymorphism Analysis ◽  
Single Mutation ◽  
Wild Type ◽  
Single Strand Conformational Polymorphism ◽  
E Coli ◽  
High Level

Twenty-eight human isolates of Escherichia coli from Argentina and Spain and eight veterinary isolates received from the Ministry of Agriculture Fisheries and Foods in the United Kingdom required 2 to > 128 micrograms of ciprofloxacin per ml for inhibition. Fragments of gyrA and parC encompassing the quinolone resistance-determining region were amplified by PCR, and the DNA sequences of the fragments were determined. All isolates contained a mutation in gyrA of a serine at position 83 (Ser83) to an Leu, and 26 isolates also contained a mutation of Asp87 to one of four amino acids: Asn (n = 14), Tyr (n = 6), Gly (n = 5), or His (n = 1). Twenty-four isolates contained a single mutation in parC, either a Ser80 to Ile (n = 17) or Arg (n = 2) or a Glu84 to Lys (n = 3). The role of a mutation in gyrB was investigated by introducing wild-type gyrB (pBP548) into all isolates; for three transformants MICs of ciprofloxacin were reduced; however, sequencing of PCR-derived fragments containing the gyrB quinolone resistance-determining region revealed no changes. The analogous region of parE was analyzed in 34 of 36 isolates by single-strand conformational polymorphism analysis and sequencing; however, no amino acid substitutions were discovered. The outer membrane protein and lipopolysaccharide profiles of all isolates were compared with those of reference strains, and the concentration of ciprofloxacin accumulated (with or without 100 microM carbony cyanide m-chlorophenylhydrazone [CCCP] was determined. Twenty-two isolates accumulated significantly lower concentrations of ciprofloxacin than the wild-type E. coli isolate; nine isolates accumulated less then half the concentration. The addition of CCCP increased the concentration of ciprofloxacin accumulated, and in all but one isolate the percent increase was greater than that in the control strains. The data indicate that high-level fluoroquinolone resistance in E. coli involves the acquisition of mutations at multiple loci.

scholarly journals High-level expression of soluble rat hsc70 in Escherichia coli: purification and characterization of the cloned enzyme

1993 ◽  
Vol 294 (1) ◽  
pp. 69-77 ◽  
Author(s):  
C Wang ◽  
M R Lee
Keyword(s):  
Escherichia Coli ◽  
Dissociation Constants ◽  
Expression System ◽  
Deae Cellulose ◽  
Basic Amino Acid ◽  
Coated Vesicle ◽  
Amino Acid Residues ◽  
High Level ◽  
Binding Component

We have cloned the cDNA of rat hsc70 (clathrin-uncoating ATPase) into a T7 expression system and have expressed this enzyme in Escherichia coli. The recombinant clathrin-uncoating ATPase is in the cytosolic fraction of the bacterium and is soluble. It was purified to homogeneity by DEAE-cellulose and ATP-agarose column chromatography. From 1 litre of bacterial culture (0.3-0.4 g of proteins), 5-20 mg of pure recombinant clathrin-uncoating ATPase was routinely obtained. The cloned enzyme is capable of dissociating clathrin from bovine coated vesicle. Furthermore, it is not methylated on basic amino acid residues and is not blocked at the N-terminus, indicating that these modifications on hsc70 are not essential for uncoating of clathrin. Binding of [alpha-32P]ATP by purified recombinant hsc70 was analysed by Scatchard plot. The results indicate that there one high-affinity binding component with a Kd (dissociation constant) of 0.2-0.3 microM. The peptide-stimulated ATPase activities of recombinant hsc70 at 37 degrees C with respect to S-peptide peptides P3a and GT4 at a concentration of 1.2 mM are 142 +/- 6, 214 +/- 8 and 362 +/- 5 pmol/h per micrograms of hsc70 protein respectively. The EC50 values of hsc70 ATPase for S-peptide, peptides P3a and GT4 are 2, 0.67 and 0.17 mM respectively. On the other hand, the dissociation constants of S-peptide, peptides P3a and GT4 for recombinant hsc70 are 7.6, 13 and 100 microM respectively. Thus peptide GT4 is the only peptide examined for which the binding constant is comparable with the EC50 for stimulation ATPase activity, albeit it has the lowest affinity for hsc70.

First characterization of fluoroquinolone resistance mechanisms in CTX-M-producing Escherichia coli from Mongolia

2016 ◽  
Vol 38 ◽  
pp. 79-81 ◽  
Author(s):  
Cheng-Yen Kao ◽  
Uuganbayar Udval ◽  
Hsiu-Mei Wu ◽  
Enkhbaatar Bolormaa ◽  
Jing-Jou Yan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Resistance Mechanisms ◽  
Fluoroquinolone Resistance
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