Bi-directional gene switching with the tetracycline repressor and a novel tetracycline antagonist.

We have screened a panel of tetracycline (tc)-like compounds for their potential use with tc-repressor (tetR) based gene switches. The interaction between tc and tetR appears quite specific, as only tc itself and its close homologues anhydro-tc and doxycycline strongly inhibited DNA binding. However, a single tc-like compound, GR33076X, increased DNA binding of the tetR-VP16 fusion protein, both in eukaryotic cells and in bacteria. We provide evidence that this antagonist of tetracycline is potentially useful for accelerated gene switching, especially in whole animals.