The phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS), a major carbohydrate active -transport system, catalyzes the phosphorylation of incoming sugar substrates concomitant with their translocation across the cell membrane. The EIIA domain is phosphorylated by phospho-HPr on a histidyl residue. Then, it transfers the phosphoryl group to the EIIB domain.