Figure 1.

Engineering synthetic receptors using the split-DBD principle (A) Overview of the LexA-based split-repressor system. LexA DBD was fused to VHH-Caffeine. The monomeric chimeric receptor is expressed in the cytosol upon IPTG induction. In the presence of caffeine, the chimeric receptor dimerizes and binds to the LexA operator, blocking expression of the reporter gene. (B) Response of cells harboring plasmids encoding LexA-VHH-Caffeine and LexA-VHH-Control to increasing concentrations of IPTG and caffeine. (C) Fold repression for the two LexA-VHH fusions in response to increasing concentrations of IPTG and caffeine. For each IPTG concentration, fold changes were calculated from (B) relatively to cells grown without caffeine (lower row).