scholarly journals Molecular analysis of lambda bio transducing phage produced by oxolinic acid-induced illegitimate recombination in vivo.

Genetics ◽  
1995 ◽  
Vol 140 (3) ◽  
pp. 889-896 ◽  
Author(s):  
H Shimizu ◽  
H Yamaguchi ◽  
H Ikeda
Keyword(s):  
Dna Gyrase ◽  
Oxolinic Acid ◽  
Illegitimate Recombination ◽  
Prophage Induction ◽  
Minority Class ◽  
E Coli ◽  
Gyrase A ◽  
A Subunit ◽  
Dependent Mechanism

Abstract To study the mechanism of DNA gyrase-mediated illegitimate recombination in Escherichia coli, we examined the formation of lambda Spi- phage during prophage induction. The frequency of Spi- phage was two to three orders of magnitude higher in the presence of oxolinic acid, an inhibitor of DNA gyrase A subunit, than in the absence of the drug, while it was very low in nalAr bacteria with the drug. RecA function is not required for the formation of these phages, indicating that this enhancement is not caused by the expression of SOS-controlled genes. Analyses of att region and recombination junctions of Spi- phages revealed that they have essentially the same structures as lambda bio transducing phages but are classified into two groups with respect to recombination sites. In the majority class of the transducing phages, there were not more than 3-bp homologies between the parental E. coli bio and lambda recombination sites. In the minority class of the transducing phages, on the other hand, 9-10-bp homologies were found between the parental recombination sites. These results suggested that oxolinic acid-induced illegitimate recombination takes place by two variants of a DNA gyrase-dependent mechanism.

scholarly journals Characterization and in Vivo Cloning of prlC, a Suppressor of Signal Sequence Mutations in Escherichia coli K12

Genetics ◽  
1987 ◽  
Vol 116 (4) ◽  
pp. 513-521
Author(s):  
Nancy J Trun ◽  
Thomas J Silhavy
Keyword(s):  
Escherichia Coli ◽  
Genetic Mapping ◽  
Signal Sequence ◽  
Illegitimate Recombination ◽  
Mutant Phenotype ◽  
E Coli ◽  
Physical Location ◽  
Sequence Deletion ◽  
New Alleles

ABSTRACT The prlC gene of E. coli was originally identified as an allele, prlC1, which suppresses certain signal sequence mutations in the genes for several exported proteins. We have isolated six new alleles of prlC that also confer this phenotype. These mutations can be placed into three classes based on the degree to which they suppress the lamBsignal sequence deletion, lamBs78. Genetic mapping reveals that the physical location of the mutations in prlC correlates with the strength of the suppression, suggesting that different regions of the gene can be altered to yield a suppressor phenotype. We also describe an in vivo cloning procedure using λplacMu9H. The procedure relies on transposition and illegitimate recombination to generate a specialized transducing phage that carries prlC1. This method should be applicable to any gene for which there is a mutant phenotype.

scholarly journals Quinolone-resistant mutants of escherichia coli DNA topoisomerase IV parC gene.

1996 ◽  
Vol 40 (3) ◽  
pp. 710-714 ◽  
Author(s):  
Y Kumagai ◽  
J I Kato ◽  
K Hoshino ◽  
T Akasaka ◽  
K Sato ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dna Gyrase ◽  
Mutant Gene ◽  
Missense Mutations ◽  
Topoisomerase Iv ◽  
Dna Topoisomerase ◽  
E Coli ◽  
A Subunit ◽  
Resistant Strains ◽  
Mutant Genes

Escherichia coli quinolone-resistant strains with mutations of the parC gene, which codes for a subunit of topoisomerase IV, were isolated from a quinolone-resistant gyrA mutant of DNA gyrase. Quinolone-resistant parC mutants were also identified among the quinolone-resistant clinical strains. The parC mutants became susceptible to quinolones by introduction of a parC+ plasmid. Introduction of the multicopy plasmids carrying the quinolone-resistant parC mutant gene resulted in an increase in MICs of quinolones for the parC+ and quinolone-resistant gyrA strain. Nucleotide sequences of the quinolone-resistant parC mutant genes were determined, and missense mutations at position Gly-78, Ser-80, or Glu-84, corresponding to those in the quinolone-resistance-determining region of DNA gyrase, were identified. These results indicate that topoisomerase IV is a target of quinolones in E. coli and suggest that the susceptibility of E. coli cells to quinolones is determined by sensitivity of the targets, DNA gyrase and topoisomerase IV.

scholarly journals The pivot point arginines identified in the β-pinwheel structure of C-terminal domain from Salmonella Typhi DNA Gyrase A subunit

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ekta Sachdeva ◽  
Gurpreet Kaur ◽  
Pragya Tiwari ◽  
Deepali Gupta ◽  
Tej P. Singh ◽  
...  
Keyword(s):  
Dna Gyrase ◽  
Salmonella Typhi ◽  
Pivot Point ◽  
Terminal Domain ◽  
Gyrase A ◽  
A Subunit

Molecular Cloning of the gyrA andgyrB Genes of Bacteroides fragilis Encoding DNA Gyrase

1999 ◽  
Vol 43 (10) ◽  
pp. 2423-2429 ◽  
Author(s):  
Yoshikuni Onodera ◽  
Kenichi Sato
Keyword(s):  
Hot Spot ◽  
Bacteroides Fragilis ◽  
Dna Gyrase ◽  
E Coli ◽  
Important Target ◽  
Mutant Strains ◽  
Genes Encoding ◽  
Gyrase A ◽  
Selection For

ABSTRACT The genes encoding the DNA gyrase A and B subunits ofBacteroides fragilis were cloned and sequenced. ThegyrA and gyrB genes code for proteins of 845 and 653 amino acids, respectively. These proteins were expressed inEscherichia coli, and the combination of GyrA and GyrB exhibited ATP-dependent supercoiling activity. To analyze the role of DNA gyrase in quinolone resistance of B. fragilis, we isolated mutant strains by stepwise selection for resistance to increasing concentrations of levofloxacin. We analyzed the resistant mutants and showed that Ser-82 of GyrA, equivalent to resistance hot spot Ser-83 of GyrA in E. coli, was in each case replaced with Phe. These results suggest that DNA gyrase is an important target for quinolones in B. fragilis.

scholarly journals Active-Site Residues of Escherichia coli DNA Gyrase Required in Coupling ATP Hydrolysis to DNA Supercoiling and Amino Acid Substitutions Leading to Novobiocin Resistance

2003 ◽  
Vol 47 (3) ◽  
pp. 1037-1046 ◽  
Author(s):  
Christian H. Gross ◽  
Jonathan D. Parsons ◽  
Trudy H. Grossman ◽  
Paul S. Charifson ◽  
Steven Bellon ◽  
...  
Keyword(s):  
Amino Acid ◽  
Atp Hydrolysis ◽  
Dna Gyrase ◽  
Dna Supercoiling ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Mutant Proteins ◽  
E Coli ◽  
Novobiocin Resistance

ABSTRACT DNA gyrase is a bacterial type II topoisomerase which couples the free energy of ATP hydrolysis to the introduction of negative supercoils into DNA. Amino acids in proximity to bound nonhydrolyzable ATP analog (AMP · PNP) or novobiocin in the gyrase B (GyrB) subunit crystal structures were examined for their roles in enzyme function and novobiocin resistance by site-directed mutagenesis. Purified Escherichia coli GyrB mutant proteins were complexed with the gyrase A subunit to form the functional A2B2 gyrase enzyme. Mutant proteins with alanine substitutions at residues E42, N46, E50, D73, R76, G77, and I78 had reduced or no detectable ATPase activity, indicating a role for these residues in ATP hydrolysis. Interestingly, GyrB proteins with P79A and K103A substitutions retained significant levels of ATPase activity yet demonstrated no DNA supercoiling activity, even with 40-fold more enzyme than the wild-type enzyme, suggesting that these amino acid side chains have a role in the coupling of the two activities. All enzymes relaxed supercoiled DNA to the same extent as the wild-type enzyme did, implying that only ATP-dependent reactions were affected. Mutant genes were examined in vivo for their abilities to complement a temperature-sensitive E. coli gyrB mutant, and the activities correlated well with the in vitro activities. We show that the known R136 novobiocin resistance mutations bestow a significant loss of inhibitor potency in the ATPase assay. Four new residues (D73, G77, I78, and T165) that, when changed to the appropriate amino acid, result in both significant levels of novobiocin resistance and maintain in vivo function were identified in E. coli.

scholarly journals The key DNA-binding residues in the C-terminal domain of Mycobacterium tuberculosis DNA gyrase A subunit (GyrA)

2006 ◽  
Vol 34 (19) ◽  
pp. 5650-5659 ◽  
Author(s):  
You-Yi Huang ◽  
Jiao-Yu Deng ◽  
Jing Gu ◽  
Zhi-Ping Zhang ◽  
Anthony Maxwell ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Dna Binding ◽  
Dna Gyrase ◽  
Terminal Domain ◽  
Gyrase A ◽  
A Subunit ◽  
Binding Residues

Vibrio harveyi RNA polymerase: purification and resolution from gyrase A

1992 ◽  
Vol 70 (8) ◽  
pp. 698-702 ◽  
Author(s):  
Elana Swartzman ◽  
Edward A. Meighen
Keyword(s):  
Rna Polymerase ◽  
Topoisomerase Ii ◽  
Vibrio Harveyi ◽  
In Vitro Transcription ◽  
E Coli ◽  
Gyrase A ◽  
A Subunit ◽  
Terminal Amino ◽  
Promoter Specificity

RNA polymerase was purified from Vibrio harveyi and found to contain polypeptides (β,β′, α, and σ) closely corresponding to those of the Escherichia coli enzyme. In vitro transcription studies using V. harveyi and E. coli RNA polymerase demonstrated that the purified V. harveyi RNA polymerase is functional and that the two enzymes have the same promoter specificity. Chromatography through a monoQ column was required to remove a 100-kilodalton protein that was present in large amounts and copurified with the RNA polymerase. N-terminal amino acid sequencing showed that the first 18 amino acids of the 100-kilodalton protein shares 78% sequence identity with the A subunit of gyrase or topoisomerase II. The abundance of the gyrase A protein is unprecedented and may be linked to bioluminescence.Key words: Vibrio harveyi, RNA polymerase, gyrase, bioluminescence.

scholarly journals Sensitization of bacteria to danofloxacin by temperate prophages.

1996 ◽  
Vol 40 (6) ◽  
pp. 1561-1563 ◽  
Author(s):  
S Froshauer ◽  
A M Silvia ◽  
M Chidambaram ◽  
B Sharma ◽  
G M Weinstock
Keyword(s):  
Escherichia Coli ◽  
Sos Response ◽  
Dna Gyrase ◽  
Pasteurella Haemolytica ◽  
Prophage Induction ◽  
E Coli

Danofloxacin (CP-76,136) is in a class of agents that inhibit DNA gyrase and trigger induction of the SOS response and temperate bacteriophages. Killing studies against the bovine pathogen Pasteurella haemolytica demonstrated that danofloxacin exhibits particularly rapid killing kinetics. Here, lysogenic Escherichia coli bearing lambda is found to be more sensitive to danofloxacin than nonlysogenic E. coli. Danofloxacin exposure also induced a prophage in P. haemolytica. The potency of danofloxacin against lysogens in likely enhanced by this prophage induction.

scholarly journals Mapping Simocyclinone D8 Interaction with DNA Gyrase: Evidence for a New Binding Site on GyrB

2009 ◽  
Vol 54 (1) ◽  
pp. 213-220 ◽  
Author(s):  
C. Sissi ◽  
E. Vazquez ◽  
A. Chemello ◽  
L. A. Mitchenall ◽  
A. Maxwell ◽  
...  
Keyword(s):  
Dna Gyrase ◽  
Coumarin Derivative ◽  
Streptomyces Antibioticus ◽  
B Subunit ◽  
Terminal Domain ◽  
Antiproliferative Agent ◽  
Gyrase A ◽  
A Subunit ◽  
The Individual ◽  
Simocyclinone D8

ABSTRACT Simocyclinone D8, a coumarin derivative isolated from Streptomyces antibioticus Tü 6040, represents an interesting new antiproliferative agent. It was originally suggested that this drug recognizes the GyrA subunit and interferes with the gyrase catalytic cycle by preventing its binding to DNA. To further characterize the mode of action of this antibiotic, we investigated its binding to the reconstituted DNA gyrase (A2B2) as well as to its GyrA and GyrB subunits and the individual domains of these proteins, by performing protein melting and proteolytic digestion studies as well as inhibition assays. Two binding sites were identified, one (anticipated) in the N-terminal domain of GyrA (GyrA59) and the other (unexpected) at the C-terminal domain of GyrB (GyrB47). Stabilization of the A subunit appears to be considerably more effective than stabilization of the B subunit. Our data suggest that these two distinct sites could cooperate in the reconstituted enzyme.

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