Tetracycline-controlled transactivator (tTAV) is a synthetic
protein coding sequence based on a fusion of sequences from
Escherichia coli and Herpes simplex virus (VP16 transcriptional
tTAV is under the control of its own binding site, tetO. In the
absence of tetracycline, tTAV binds to tetO and drives expression
of more tTAV, in a positive feedback loop. In the presence of
tetracycline, tTAV binds tetracycline; this tetracycline-bound form
does not bind tetO and so does not lead to expression of more tTAV.
Consequently, this construct gives very high levels of expression
of tTAV in the absence of tetracycline, but only low, basal
expression in the presence of tetracycline.
tTAV encodes a dominant trait that, when introduced into certain
insects, causes death of the insect unless the antibiotic
tetracycline is supplied.