Bacterial DNA gyrase and DNA topoisomerase IV

Bacterial DNA gyrase and DNA topoisomerase IV are two essential Type II topoisomerase enzymes found in bacteria. DNA gyrase primarily catalyzes the ATP-dependent introduction of negative supercoils into double-stranded DNA and is unique to bacteria. It plays a central role in resolving topological stress ahead of the replication fork during DNA replication, thus facilitating continued synthesis and genome maintenance[5][6]. DNA topoisomerase IV is responsible for decatenation, i.e., unlinking of interlinked (catenated) daughter chromosomes following DNA replication, and also helps relax positive supercoils[1][2][3][4]. Both enzymes function as heterotetramers: DNA gyrase is composed of GyrA and GyrB subunits, while topoisomerase IV consists of ParC and ParE subunits[1][4]. These enzymes are critical for bacterial viability and are prime targets for antibiotics, especially fluoroquinolones and related drugs, which trap enzyme-DNA complexes and induce lethal double-strand DNA breaks[3]. Resistance to these antibiotics frequently involves mutations in the genes encoding their subunits. Both enzymes are absent in higher eukaryotes (which have related topoisomerases but lack DNA gyrase specifically), making them attractive and selective antibacterial drug targets.

Other names

DNA gyraseGyraseDNA topoisomerase II (bacterial)Topoisomerase IVTopo IV

Inhibition of DNA supercoiling (gyrase) and decatenation (topoisomerase IV), leading to impaired DNA replication and segregation Stabilization of enzyme-DNA cleavage complexes, causing double-strand DNA breaks and cell death