Might be involved in fluoroquinolone resistance (PubMed:15933203). Inhibits ATP-independent DNA relaxation, ATP-dependent DNA supercoiling and ATP-dependent decatenation by endogenous gyrase, 50% inhibition occurs at 2 uM; inhibition is abolished if GyrA is mutated (Asp-87 to Gly or His) (PubMed:19060136). Also inhibits fluoroquinolone-promoted dsDNA cleavage (PubMed:19060136). Increases fluoroquinolone (ciprofloxacin or moxifloxacin) inhibition of gyrase supercoiling activity in a concentration-dependent manner (PubMed:19060136). Inhibits DNA relaxation and supercoiling by E.coli gyrase (PubMed:15933203). Forms a structure that exhibits size, shape and electrostatic similarity to B-form DNA; it may bind to DNA gyrase which is postulated to protect it from fluoroquinolones (PubMed:15933203). Homodimer. Probably interacts with DNA gyrase. Each subunit forms a right-handed beta-helix with 8 complete coils that stack upon each other. Belongs to the pentapeptide repeat protein family.