Listeria monocytogenes Scott A transports glucose by high-affinity and low-affinity glucose transport systems

Listeria monocytogenes transported glucose by a high-affinity phosphoenolpyruvate-dependent phosphotransferase system and a low-affinity proton motive force-mediated system. The low-affinity system (Km = 2.9 mM) was inhibited by 2-deoxyglucose and 6-deoxyglucose, whereas the high-affinity system (Km = 0.11 mM) was inhibited by 2-deoxyglucose and mannose but not 6-deoxyglucose. Cells and vesicles artificially energized with valinomycin transported glucose or 2-deoxyglucose at rates greater than those of de-energized cells, indicating that a membrane potential could drive uptake by the low-affinity system.