Bacterial DNA gyrase (cleaved enzyme-DNA complex) (DNA gyrase)

Bacterial DNA gyrase is an essential Type II topoisomerase that introduces negative supercoils into DNA, a process critical for DNA replication, transcription, and chromosome segregation (UniProt P0AES4, P0A6C5). The enzyme functions by creating a transient double-strand break in the DNA, passing another segment of the DNA duplex through the gap, and then resealing the break (PubMed: 20533938). The "cleaved enzyme-DNA complex" is a specific catalytic intermediate where the DNA is covalently attached to the enzyme's active site tyrosine residues. This complex is the primary target for fluoroquinolone antibiotics, which act as "topoisomerase poisons" by binding to and stabilizing this intermediate state (StatPearls: Fluoroquinolones). By preventing the religation of the DNA, these drugs cause the accumulation of permanent double-strand breaks, which ultimately leads to bacterial cell death. This target is vital for treating various bacterial infections, although its clinical utility is increasingly challenged by the emergence of resistance mutations in the gyrase subunits (PubMed: 25108112). Unlike eukaryotic topoisomerases, DNA gyrase is unique to bacteria, providing a high degree of selective toxicity for antimicrobial therapy.

Other names

DNA topoisomerase IIGyrase-DNA cleavage complexTopoisomerase II-DNA complexGyrA2B2 complex

Stabilization of the covalent enzyme-DNA cleavage complex, which prevents DNA religation and leads to lethal double-strand breaks (PubMed: 20533938).