The bacterial tetracycline transcription regulation system mediated by the tetracycline repressor (TetR) is widely used to study gene expression in prokaryotes and eukaryotes. To study multiple genes in parallel, a triple mutant TetR(K 64 L 135 I 138 ) has been engineered that is selectively induced by the synthetic tetracycline derivative 4-de-dimethylamino-anhydrotetracy-cline (4-ddma-atc) and no longer by tetracycline, the inducer of wild-type TetR. In the present study
