Movement of the transcription machinery along a template alters DNA topology resulting in the accumulation of supercoils in DNA. The positive supercoils generated ahead of transcribing RNA polymerase (RNAP) and the negative supercoils accumulating behind impose severe topological constraints impeding transcription process. Previous studies have implied the role of topoisomerases in the removal ...

A class of gyrase mutants of Salmonella enterica mimics the properties of bacteria exposed to quinolones. These mutants suffer spontaneous DNA breakage during normal growth and depend on recombinational repair for viability. Unlike quinolone-treated bacteria, however, they do not show accumulation of cleavable gyrase-DNA complexes. In recA or recB mutant backgrounds, the temperature-sensitive (...

BACKGROUND Fluoroquinolones represent a potent group of antibiotics that inhibit bacterial DNA replication by targeting the essential bacterial enzymes gyrase and topoisomerase IV. Inhibition of gyrase activity by quinolones involves the interaction of these drugs with the helicase component of bacterial gyrase. DNA tumour viruses also encode helicases that are essential for their DNA replicati...

Reverse gyrase introduces positive supercoils to circular DNA and is implicated in genome stability maintenance in thermophiles. The extremely thermophilic crenarchaeon Sulfolobus encodes two reverse gyrase proteins, TopR1 (topoisomerase reverse gyrase 1) and TopR2, whose functions in thermophilic life remain to be demonstrated. Here, we investigated the roles of TopR1 in genome stability maint...

Differentiation among types I, II, and III is the primary step in typing Mycobacterium avium subsp. paratuberculosis. We propose an innovative approach based on detection of gyrase B (gyrB) gene polymorphisms by suspension array technology, with high discriminatory power and high-throughput potential.

Quinolones that act equally against DNA gyrase and topoisomerase IV are a desirable modality to decrease the selection of resistant strains. We first determined by genetic and biochemical studies in Staphylococcus aureus that the primary target enzyme of WCK-1734, a new quinolone, was DNA gyrase. A single mutation in gyrase, but not topoisomerase IV, caused a two- to fourfold increase in the MI...

The hyperthermophilic bacterium Thermotoga maritima MSB8 possesses a reverse gyrase whose enzymatic properties are very similar to those of archaeal reverse gyrases. It catalyzes the positive supercoiling of the DNA in an Mg2+- and ATP-dependent process. Its optimal temperature of activity is around 90 degrees C, and it is highly thermostable. We have cloned and DNA sequenced the corresponding ...

Treatment of bacterial cells with inhibitors of gyrase at high concentration leads to relaxation of DNA supercoils, presumably through interference with the supercoiling activity of gyrase. Under certain conditions, however, the inhibitors can also increase supercoiling. In the case of coumermycin A1, this increase occurs at low drug concentrations. Oxolinic acid increases supercoiling in a par...

Genetic and environmental perturbations often result in complex transcriptional responses involving multiple genes and regulons. In order to understand the nature of a response, one has to account for the contribution of the downstream effects to the formation of a response. Such analysis can be carried out within a statistical framework in which the individual effects are independently collect...