Visualization of topoisomerases in live Bacillus subtilis cells showed that Topo I, Topo IV, and DNA gyrase differentially localize on the nucleoids but are absent at cytosolic spaces surrounding the nucleoids, suggesting that these topoisomerases interact with many regions of the chromosome. While both subunits of Topo IV were uniformly distributed throughout the nucleoids, Topo I and gyrase f...

We used DNA microarrays of the Escherichia coli genome to trace the progression of chromosomal replication forks in synchronized cells. We found that both DNA gyrase and topoisomerase IV (topo IV) promote replication fork progression. When both enzymes were inhibited, the replication fork stopped rapidly. The elongation rate with topo IV alone was 1/3 of normal. Genetic data confirmed and exten...

Fluoroquinolone resistance in Mycobacterium tuberculosis has become increasingly important. A review of mutations in DNA gyrase, the fluoroquinolone target, is needed to improve the molecular detection of resistance. We performed a systematic review of studies reporting mutations in DNA gyrase genes in clinical M. tuberculosis isolates. From 42 studies that met inclusion criteria, 1220 fluoroqu...

Reverse gyrase is a topoisomerase that can introduce positive supercoils to its substrate DNA. It is demonstrated in our studies that a highly thermal stable G-quadruplex structure in a mini-plasmid DNA was transformed into its duplex conformation after a treatment with reverse gyrase. The structural difference of the topoisomers were verified and analyzed by gel electrophoresis, atomic force m...

The mechanism of type II DNA topoisomerases involves the formation of an enzyme-operated gate in one double-stranded DNA segment and the passage of another segment through this gate. DNA gyrase is the only type II topoisomerase able to introduce negative supercoils into DNA, a feature that requires the enzyme to dictate the directionality of strand passage. Although it is known that this is a c...

Inhibitors of DNA gyrase in Escherichia coli exerted differential effects on the genetic transformation of Neisseria gonorrhoeae. When competent cells of the gonococcus were exposed to novobiocin before the uptake of transforming antibiotic resistance DNA, there was a 50 to 60% reduction in the number of transformants compared with the number of control untreated cells. Norfloxacin, a more pote...

DNA gyrase catalyses the adenosine triphosphate-dependent introduction of negative supercoils into DNA. The enzyme binds a DNA-segment at the so-called DNA-gate and cleaves both DNA strands. DNA extending from the DNA-gate is bound at the perimeter of the cylindrical C-terminal domains (CTDs) of the GyrA subunit. The CTDs are believed to contribute to the wrapping of DNA around gyrase in a posi...

Abstract DNA gyrase, a type II topoisomerase found predominantly in bacteria, is the target for variety of ‘poisons’, namely natural product toxins (e.g. albicidin, microcin B17) and clinically important synthetic molecules fluoroquinolones). Resistance to both groups can be mediated by pentapeptide repeat proteins (PRPs). Despite long-term studies, mechanism action these protective PRPs not kn...