Coli DNA Topoisomerase Research Articles

In vitro antimicrobial evaluation and in silico studies of coumarin derivatives tagged with pyrano-pyridine and pyrano-pyrimidine moieties as DNA gyrase inhibitors.

Several coumarin-containing substitute nitrogen heterocycles have recently received considerable importance due to their diverse pharmacological properties. One-pot and rapid synthesis of coumarin derivatives was achieved via reactions of acetyl-coumarin with p-chloro-benzaldehyde and malononitrile to provide compound 2-containing cyano-amine using conventional heating. Compound 2 was condensed with different carbon electrophiles triethyl orthoformate, phenyl isocyanate, carbon disulfide, benzoyl chloride, and acetyl chloride that afforded the corresponding chromene derivatives 3-17. All the newly synthesized compounds were characterized by elemental and spectroscopic evidences. All of the synthesized compounds were tested for antimicrobial activity against S. Pneumoniae, S. Epidermidis, S. Aureus, and E. coli as Gram + ve Bacteria, K. Pneumoniae, S. Paratyphi as Gram -ve Bacteria, P. Italicum, A. Fumigatus representative for Fungi. The preliminary screening results showed that most of the compounds had moderate to high activity against all tested organisms. The most potent four compounds were subjected to further investigation against E. Coli DNA gyrase and topoisomerase IV inhibitory activity, and the results showed that all of these derivatives inhibit DNA gyrase and thus cell division. Also, in silico studies were done for the most active compounds which showed good results.

Synthesis, characterization, and investigation of singlet oxygen, DNA interaction,and topoisomerase I inhibition properties of novel zinc(II) phthalocyanine

In this work, phthalonitrile (3) and zinc(II) phthalocyanine (4) were prepared. To determine the photodynamic therapy potential of compound 4, singlet oxygen quantum yield, DNA binding and cleavage, and topoisomerase I inhibition experiments were performed. The singlet oxygen quantum yield value of compound 4 was found higher than that of the standard unsubstituted zinc(II) phthalocyanine compound (Std-ZnPc). The binding experiments showed that compound 4 interacted with ct-DNA strongly via nonintercalation mode. pBR322 plasmid DNA cleavage activity of the compound was investigated using agarose gel electrophoresis. The results showed that the compound 4 had important DNA cleavage activity. The E. coli DNA topoisomerase I inhibition effects of compound 4 were investigated using agarose gel electrophoresis. Compound 4 had an E. coli topoisomerase I inhibitory effect at increasing concentrations. The results showed that compound 4 has photosensitizer potential in photodynamic therapy.

A rapid procedure to purify Escherichia coli DNA topoisomerase I

On the basis of the asymmetrical charge distribution of Escherichia coli DNA topoisomerase I, we developed a new procedure to purify E. coli DNA topoisomerase I in the milligram range. The new procedure includes using both cation- and anion-exchange columns, i.e., SP-Sepharose FF and Q-Sepharose FF columns. The E. coli DNA topoisomerase I purified here is free of DNase contamination. The kinetic constants of the DNA relaxation reaction of E. coli DNA topoisomerase I were also determined.

Strand Invasion Structures in the Inverted Repeat of Candida albicans Mitochondrial DNA Reveal a Role for Homologous Recombination in Replication

Molecular recombination and transcription are proposed mechanisms to initiate mitochondrial DNA (mtDNA) replication in yeast. We conducted a comprehensive analysis of mtDNA from the yeast Candida albicans. Two-dimensional agarose gel electrophoresis of mtDNA intermediates reveals no bubble structures diagnostic of specific replication origins, but rather supports recombination-driven replication initiation of mtDNA in yeast. Specific species of Y structures together with DNA copy number analyses of a C. albicans mutant strain provide evidence that a region in a mainly noncoding inverted repeat is predominantly involved in replication initiation via homologous recombination. Our further findings show that the C. albicans mtDNA forms a complex branched network that does not contain detectable amounts of circular molecules. We provide topological evidence for recombination-driven mtDNA replication initiation and introduce C. albicans as a suitable model organism to study wild-type mtDNA maintenance in yeast.

Increased sensitivity to oxidative challenges associated with topA deletion in Escherichia coli.

Deletion of topA in Escherichia coli was found to result in a higher level of killing after treatment with either hydrogen peroxide or N-ethylmaleimide. This effect on oxidative challenge response represents a new role for E. coli DNA topoisomerase I in addition to prevention of excessive negative supercoiling of DNA.

Mechanism of type II DNA topoisomerases: a tale of two gates.

Mechanism of type II DNA topoisomerases: a tale of two gates.

DNA topoisomerases: essential enzymes and lethal targets.

INTRODUCTION In 1971, Wang (1) discovered the first DNA topoisomerase in Escherichia coli. The enzyme (E. coli DNA topoisomerase I, or w protein) catalyzed relaxation of negatively supercoiled DNA in the absence of any energy cofactor (1). Wang proposed that this enzyme also catalyzed transient nicking of the DNA double helix and possessed both DNase and ligase activity in one polypeptide (1). The lack of any energy cofactor for the reaction also led Wang to the proposal that the enzyme may form a high-energy covalent bond between itself and the transiently broken DNA phosphodiester bond (1). Both of these predictions have turned out to be correct (2). Since the discovery of E. coli topoisomerase I, investigators have isolated many other DNA topoisomerases from both prokaryotes and eukaryotes. In 1972, Champoux & Dulbecco isolated an enzyme with activity similar to that of E. coli topoisomerase I from mouse embryo cells (3). In 1976, Gellert and his colleagues identified an enzyme activity opposing E. coli DNA topoisomerase I (4). They demonstrated that this enzyme (E. coli DNA topoisomerase II, or gyrase) catalyzed the conversion of relaxed DNA into negatively supercoiled DNA in a reaction requiring ATP hydrolysis (4). These two opposing activities are important for maintaining the super­ helical state of the chromosomal DNA during various DNA transactions (5-8). In 1979, Liu et al (9) isolated an enzyme from bacteriophage

A pSC101-parsequence-mediated study on the intracellular state of supercoiling of the pBR322 genome inEscherichia coliDNA topoisomerase I deletion mutant

A pSC101-<i>par</i>sequence-mediated study on the intracellular state of supercoiling of the pBR322 genome in<i>Escherichia coli</i>DNA topoisomerase I deletion mutant

Elution of proteins from sodium dodecyl sulfate-polyacrylamide gels, removal of sodium dodecyl sulfate, and renaturation of enzymatic activity: Results with sigma subunit of Escherichia coli RNA polymerase, wheat germ DNA topoisomerase, and other enzymes

An improved method is described for the renaturation of microgram amounts of proteins from sodium dodecyl sulfate-polyacrylamide gels. The protein band is visualized in the gel by KCl staining, the band cut out and crushed, and the protein eluted by diffusion in a buffer containing 0.1% sodium dodecyl sulfate. Protein is concentrated and sodium dodecyl sulfate is removed by acetone precipitation of the sample. Renaturation of the protein occurs after the precipitate is dissolved in 6 m guanidine hydrochloride and then diluted. The activity of the sigma subunit of Escherichia coli RNA polymerase can be recovered with 98–100% efficiency after electrophoresis in an SDS-gel and renaturation by this technique. To assess whether the method is generally applicable we tested some or all of the steps involved in the procedure using E. coli transcription termination factor rho, β-galactosidase, alkaline phosphatase, wheat α-amylase, and DNA topoisomerase. We show how the method can be used to determine the approximate molecular weight of the DNA topoisomerase polypeptide by sectioning a gel on which a partially pure sample has been fractionated by electrophoresis.