A Fluoroquinolone Resistance Protein from Mycobacterium tuberculosis That Mimics DNA

Abstract
Fluoroquinolones are gaining increasing importance in the treatment of tuberculosis. The expression of MfpA, a member of the pentapeptide repeat family of proteins from Mycobacterium tuberculosis , causes resistance to ciprofloxacin and sparfloxacin. This protein binds to DNA gyrase and inhibits its activity. Its three-dimensional structure reveals a fold, which we have named the right-handed quadrilateral β helix, that exhibits size, shape, and electrostatic similarity to B-form DNA. This represents a form of DNA mimicry and explains both its inhibitory effect on DNA gyrase and fluoroquinolone resistance resulting from the protein's expression in vivo.