The bacterial phosphotransferase system: new frontiers 30 years later.

In 1964, Kundig, Ghosh and Roseman reported the discovery of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). Thirty years later, we find that the PTS functions not only as a sugar-phosphorylating system, but also as a complex protein kinase system that regulates a wide variety of metabolic processes and controls the expression of numerous genes. As a result of recent operon- and genome-sequencing projects, novel PTS protein-encoding genes have been discovered, most of which have yet to be functionally defined. Some of them appear to be involved in cellular processes distinct from those recognized previously. Fundamental aspects of past and current PTS research are briefly reviewed, and recent advances are integrated into conceptual pictures that provide guides for future research.