TetR

Tetracycline (tc) is a broad family of antibiotics to which bacteria have evolved resistance. The expression of tc resistance genes is regulated by Tet Repressor Protein, called TetR.

TetR is used in artificially engineered gene regulatory networks because of its capacity for fine regulation. In the absence of tc, basal expression of TetR is very low, but expression rises sharply in the presence of even a minute quantity of tc through a positive feedback mechanism.