FIG. 1.
Modified LexA-based system for investigating protein-protein interactions. The LexA-based system was based on that of Dmitrova et al. (6). A homodimerizing fusion expressed from one of the wild-type (wt) LexA DBD::MCS plasmids (pSR658, pSR660, or pSR662) will bind to the wild-type LexA operator and repress expression of lacZ in the chromosome of the reporter strain SU101. A heterodimerizing fusion, one subunit expressed from one of the wild-type LexA DBD::MCS plasmids and the other from one of the mutated (mut) LexA DBD::MCS plasmids (pSR659, pSR661, or pSR663), will bind to the hybrid LexA operator and repress expression of lacZ in the chromosome of the reporter strain SU202. The choice of plasmid MCS (A, B, or C) is made according to the reading frame of the desired fusion. Wild-type and mutated DBD correspond to LexA1–87WT and LexA1–87408, respectively (6).