Characterization of T7 specific RNA polymerase. III. Inhibition by derivatives of rifamycin SV

Abstract

Derivatives of rifamycin SV which contain a variety of substituents at C-4 of the napthoquinone ring are active inhibitors of T7 specific RNA polymerase. Several of the drugs appear to inhibit RNA chain initiation in preference to RNA chain elongation. Studies of the kinetics of T7 RNA synthesis in the presence of one such derivative suggest that there are several large transcription units of differing sizes in the late region of T7 DNA. Other rifamycin SV derivatives inhibit both chain initiation and chain elongation suggesting that there may be 2 sites on T7 RNA polymerase at which rifamycin derivatives can act.