MODE OF ACTION OF GR122222X, A NOVEL INHIBITOR OF BACTERIAL-DNA GYRASE

GR122222X is a potent inhibitor of the supercoiling reaction of bacter ial DNA gyrase. We show that this compound binds stoichiometrically to inactivate the ATPase activity of a 43-kDa N-terminal fragment of the B subunit and competitively inhibits the binding of a radiolabelled c oumarin drug to N-terminal fragments of GyrB. These and other data sug gest that GR122222X has a mode of action similar, but not identical, t o that of coumarin antibiotics.