BACTERIOCINS INHIBIT GLUCOSE PEP-PTS ACTIVITY IN LISTERIA-MONOCYTOGENES BY INDUCED EFFLUX OF INTRACELLULAR METABOLITES

Glucose transport by the phosphoenolpyruvate (PEP)-dependent phosphotr ansferase system (PTS) of Listeria monocytogenes is inhibited by the b acteriocins nisin, pediocin JD and leuconocin S. To investigate the me chanism of inhibition, PTS activity assays were performed with permeab ilized, bacteriocin-treated L. monocytogenes Scott. A cells. In the pr esence of exogenous PEP, nisin stimulated the PTS while both pediocin JD and leuconocin S partially inhibited its activity. These results su ggested that PTS enzymes were still active in bacteriocin-treated cell s and that bacteriocin-induced PEP efflux may be a mechanism for inhib ition of the PTS. To verify that PEP did efflux from bacteriocin-treat ed L. monocytogenes Scott A cells, intracellular and extracellular PEP were measured by HPLC. All three bacteriocins induced efflux of PEP. Nisin, pediocin ID and leuconocin S also induced efflux of AMP, ADP an d ATP. These studies indicate that bacteriocin inhibition of the gluco se PEP:PTS in L. monocytogenes is due to efflux of intracellular metab olites, particularly PEP.