DNA Gyrase (Bacterial Type II Topoisomerase) (DNA Gyrase)

DNA gyrase is an essential bacterial enzyme classified as a type II topoisomerase. It catalyzes the ATP-dependent introduction of negative supercoils into double-stranded, closed-circular DNA, a function unique among topoisomerases. This activity is critical for managing DNA topology during processes such as replication and transcription in bacteria. The enzyme is a heterotetramer composed of two GyrA and two GyrB subunits. GyrA subunit is responsible for binding and encapsulating DNA; contains the active site tyrosine. GyrB subunit contains ATP-binding and hydrolysis sites. Essential in all bacteria but absent from higher eukaryotes—making it an attractive target for antibacterial drugs such as fluoroquinolones. These drugs inhibit gyrase activity either by stabilizing cleavage complexes or blocking enzymatic function directly. Resistance development has prompted ongoing research into new inhibitors targeting different aspects or conformations within its catalytic cycle.

Other names

Bacterial Type II TopoisomeraseGyraseTopoisomerase II (Bacterial)

Fluoroquinolones inhibit gyrase activity either by stabilizing cleavage complexes or blocking enzymatic function directly.