ABSTRACT
It is important to understand the metabolism and its regulation for the proper design of the cell systems for the efficient production of biofuels and biochemicals. Here, the brief explanation is given for transport of carbohydrates and carbon catabolite repression (CCR). Various carbohydrates are transported through outer membrane porin proteins, where the two-component signal transduction system composed of sensor protein and the response regulator plays important roles. The typical porins are OmpC and OmpF in Escherichia coli, and the porin genes are typically controlled by such two-component system as EnvZ-OmpR. The carbohydrates transported into the periplasm are internalized into the cytosol by various transport mechanisms, where the typical group translocation is made by the phosphotransferase system (PTS) in bacteria and some archaea. The PTS is related to the catabolite repression for the selective assimilation of carbohydrates.
