Glucose transport in Escherichia coli

J.J. Different mechanisms of glucose transport and their distribution Glucose plays a special role among sugars because it can directly enter the glycolytic pathway. For many eucaryotic cells glucose is the only useful energy source. Bacteria can utilize a much greater variety of sugars, but given a choice prefer glucose. The presence in many bacteria of two different glucose permeases and the influence of glucose on metabolic regulation further corroborate its predominant role. In cells growing in the presence of glucose, the synthesis of enzymes that process nutrients less readily metabolizable than glucose is strongly reduced (glucose effect, catabolite repression, diauxic growth [1,2]). Escherichia coli make use of a mechanism for glucose uptake which characteristically couples sugar transport with sugar phosphorylation. It depends on phosphoenolpyruvate as the phosphoryl donor, a requirement which establishes a direct link between the uptake and the glycolysis of the sugars. Such a mechanism which couples transport of a substrate with its chemical modification is termed group translocation. P-enolpyruvate dependent sugar transport is found in most faculta-