Improved vectors for nisin-controlled expression in gram-positive bacteria

A set of shuttle vectors, able to replicate in Escherichia coli and in gram-positive bacteria, containing a nisin-inducible promoter (PnisA) and genes encoding NisR and NisK, the two-component signaling mechanism for activating transcription from PnisA in the presence of nisin, was constructed. To test these vectors, Enterococcus faecalis pCF10 plasmid genes prgX, prgY, and prgZ, which respectively encode cytosolic, integral membrane, and cell surface proteins, were cloned downstream of PnisA. Increased protein expression, in the presence of nisin, was demonstrated by Western blot analysis.