Bacterial DNA gyrase–DNA complex (DNA gyrase)

The Bacterial DNA gyrase–DNA complex is a critical intermediate in the catalytic cycle of DNA gyrase, an essential type II topoisomerase found in bacteria (PubMed: 10640677). This complex is formed when the heterotetrameric enzyme, consisting of GyrA and GyrB subunits, binds to and cleaves double-stranded DNA to introduce negative supercoils (UniProt: P0AES4). This process is fundamental for relieving torsional strain during DNA replication and transcription, ensuring the bacterial genome remains accessible and functional (StatPearls: NBK547665). The complex is the primary pharmacological target for fluoroquinolone antibiotics, which bind at the interface of the enzyme and the DNA (PubChem: CID 2764). By stabilizing this 'cleavage complex,' the drugs prevent the religation of the DNA strands, effectively converting the enzyme into a cellular toxin that generates permanent double-strand breaks (PubMed: 21696353). The clinical effectiveness of targeting this complex is frequently compromised by mutations in the GyrA or GyrB subunits that reduce drug affinity, leading to widespread antibiotic resistance (PubMed: 12654733).

Other names

Type II topoisomeraseGyrA-GyrB complexDNA topoisomerase IIGyrase-DNA complex

Stabilization of the covalent enzyme-DNA cleavage complex, preventing DNA religation and inducing double-strand breaks.