The Lac-Tet inducible AND gate expression module is a set of three genetic constructs that encodes expression in the presence of both IPTG and aTc.
The three genetic constructs are as follows:
The pT7-tetO-lacO-plamGFP construct constitutively express plamGFP. The construct is MoClo compatible and plamGFP can be easily swapped for any gene of interest.
Addition of Tet repressor protein (TetR, shown in orange) and Lac repressor protein (LacI, shown in blue) to the system, whether as a purified protein or via constitutive expression of the pT7-TetR construct and pT7-LacI constructs, inhibits expression of the pT7-tetO-lacO-plamGFP construct. The mechanism of action is steric inhibition of the promoter site via Tet repressor binding to the tetO operator site and Lac repressor binding to the lacO operator site:
Addition of aTc (solid blue) and IPTG (solid orange) to the repressed system leads to recovery of expression of the pT7-tetO-lacO-plamGFP construct. The mechanism of action is allosteric binding of aTc to Tet repressor causing weakened binding and release of Tet repressor from the tetO site & likewise for IPTG binding to Lac repressor.
A variant of the pT7-tetO-lacO-plamGFP construct is available in which the two operator sites are swapped: pT7-lacO-tetO-plamGFP .