gyrB Mutations in Coumermycin Al-Resistant Borrelia burgdorferi

We have isolated and characterized mutants of Borrelia burgdorferi that are resistant to the antibiotic coumermycin A1, which targets the B subunit of DNA gyrase. Mutants had either 100- or 300-fold higher resistance to coumermycin A1 than wild-type B. burgdorferi. In each case, a single point mutation in the gyrB gene converted Arg-133 to Gly or Ile. Mutations in the homologous Arg residue of Escherichia coli DNA gyrase are also associated with resistance to coumarin antimicrobial agents. Lyme disease in North America is caused by the spirochete Borrelia burgdorferi (4, 38). B. burgdorferi has an unusual eubacterial genome composed of mostly linear DNA mole