LISTERIA-MONOCYTOGENES SCOTT-A TRANSPORTS GLUCOSE BY HIGH-AFFINITY AND LOW-AFFINITY GLUCOSE-TRANSPORT SYSTEMS

Listeria monocytogenes transported glucose by a high-affinity phosphoe nolpyruvate-dependent phosphotransferase system and a low-affinity pro ton motive force-mediated system. The low-affinity system (K-m = 2.9 m M) was inhibited by 2-deoxyglucose and 6-deoxyglucose, whereas the hig h-affinity system (K-m = 0.11 mM) was inhibited by 2-deoxyglucose and mannose but not 6-deoxyglucose. Cells and vesicles artificially energi zed,vith valinomycin transported glucose or 2-deoxyglucose at rates gr eater than those of de-energized cells, indicating that a membrane pot ential could drive uptake by the low-affinity system.