The phosphoenolpyruvate phosphotransferase system regulates cell length and width through semi-independent pathways

It has been known for over 80 years that bacterial cell size is affected by growth conditions. Cells grown in a nutrient-rich medium are larger and wider than those grown in a nutrient-poor medium. Yet even after decades of research, it is still not fully known how metabolism and cell size are coregulated. In this work, we describe a new source of metabolic control over Escherichia coli cell size, the phosphoenolpyruvate phosphotransferase system (PTS). The PTS is used to phosphorylate sugars upon entry into the cell. We found that mutations in this system result in both shorter and thinner cells and that the regulation of both dimensions of cell size appears to come from two separate mechanisms. The first mechanism regulates cell length through the production of cAMP, while the second mechanism regulates cell width through control of the levels of PEP or pyruvate in the cell.