Novobiocin inhibits Xenopus transcription factor IIIA-DNA interactions

Novobiocin and coumermycin, inhibitors of the B subunit of Escherichia coli DNA gyrase, inhibit the binding of Xenopus transcription factor IIIA (TFIIIA) to the 5 S RNA gene. Nalidixic acid and oxolinic acid, inhibitors of the A subunit of DNA gyrase, have no effect on the TFIIIA-5 S RNA gene interaction. Novobiocin and coumermycin inhibit TFIIIA-dependent DNA renaturation. Novobiocin dissociates TFIIIA.5 S RNA gene complexes and TFIIIA.5 S RNA complexes (7 S particles). Novobiocin induces TFIIIA aggregation, a phenomenon likely to be responsible for the inhibition of TFIIIA-DNA interactions. Novobiocin inhibition of TFIIIA can be reversed by dilution.