The inducible LEXSY enables tight control of protein expression analogous to the well-known bacterial T7 RNA polymerase/TET repressor architecture. Expression is switched on by addition of an inducer (tetracycline) and thereby alleviates potential toxicity issues of an expressed protein. Further, it was shown for a number of intracellular proteins that inducible expression achieves 5 - 10-fold higher yields than constitutive expression. Selection is performed with the antibiotics LEXSY Neo or LEXSY Bleo. Expression vectors with both alternative markers can be introduced into the same cell for co-expression of two proteins.
The 3rd generation of genome-integrated inducible LEXSY now allows convenient co-expression of the protein of interest with BleCherry conferring both, antibiotic resistance for selection with the antibiotic LEXSY Bleo as well as visible fluorescence under daylight as a direct read out for protein production.