parCparE

parCparE refers to the two-subunit enzyme topoisomerase IV in bacteria, consisting of the ParC and ParE subunits. The parC and parE genes are often located together in an operon and co-transcribed, encoding the A and B components of the enzyme, respectively.

Topoisomerase IV is a type II topoisomerase that plays a central role in chromosome management, especially in decatenation of replicated DNA to allow proper chromosome segregation. The ParC subunit provides the DNA cleavage and religation activities and binds to the DNA, while the ParE subunit supplies the ATPase activity that powers the strand passage step. The functional enzyme is typically a ParC2ParE2 complex.

Mechanistically, topoisomerase IV creates transient double-stranded breaks in a segment of DNA (the G-segment), passes another DNA duplex (the T-segment) through the break, and reseals the breaks. This decatenation activity helps separate newly replicated chromosomes after DNA replication.

ParCparE is a known target of fluoroquinolone antibiotics, which stabilize the enzyme–DNA cleavage complex and impede DNA replication. Resistance to quinolones commonly arises from mutations in the quinolone-resistance determining regions of parC and/or parE, reducing drug binding while preserving enzyme activity. Additional mutations or regulatory changes can further influence resistance levels.

In summary, parCparE denotes the genes encoding the two subunits of bacterial topoisomerase IV, a key enzyme for decatenation and a major target of quinolone antibiotics, with implications for bacterial genetics and antimicrobial resistance.