Expression of mptC of Listeria monocytogenes induces sensitivity to class IIa bacteriocins in Lactococcus lactis.

Sensitivity to class IIa bacteriocins from lactic acid bacteria was recently associated with the mannose phosphotransferase system (PTS) permease, in Listeria monocytogenes. To assess the involvement of this protein complex in class IIa bacteriocin activity, the mptACD operon, encoding, was heterologously expressed in an insensitive species, namely Lactococcus lactis, using the NICE double plasmid system. Upon induction of the cloned operon, the recombinant Lc. lactis became sensitive to leucocin A. Pediocin PA-1 and enterocin A also showed inhibitory activity against Lc. lactis cultures expressing mptACD. Furthermore, the role of the three genes of the mptACD operon was investigated. Derivative plasmids containing various combinations of these three genes were made from the parental mptACD plasmid by divergent PCR. The results showed that expression of mptC alone is sufficient to confer sensitivity to class IIa bacteriocins in Lc. lactis.