Bacterial phosphotransferase system (PTS) in carbohydrate uptake and control of carbon metabolism

More than 20 carbohydrates may be transported into the bacterial cell by the phosphoenopyruvate:carbohydrate phosphotransferase system (PTS) that is widely spread among bacteria. The PTS consists of two cytoplasmic energy-coupling proteins (Enzyme I and HPr) and a range of carbohydrate-specific Enzymes II, which catalyze concomitant carbohydrate translocation and phosphorylation. The phosphorylation status of PTS components reflects the availability of carbohydrates and the energy conditions of the cell. In many bacteria, PTS and the associated proteins convert this information to signals, which transduced through different mechanisms lead to phenomena of catabolite repression, inducer control or chemotaxis. These features of PTS provide bacteria with an integrated system, which assures optimal utilization of carbohydrates in complex environments. Furthemore, some bacteria evolved parallel systems that serve a regulatory functions, but apparently do not catalyze the carbohydrate transport. Here we review the findings that recently advanced the understanding of various aspects of PTS-dependent carbohydrate transport and regulation of bacterial catabolism.