GENERAL MICROBIOLOGY - T.P. Pyrog - 2004

11. FUNDAMENTAL MECHANISMS OF METABOLISM AND ENERGY CONVERSION IN MICROORGANISMS

11.7. SUBSTRATE UPTAKE MECHANISMS

11.7.4. Group Translocation

This process differs from Active Transport in that the substrate appears inside The Cell in a chemically modified form, typically as a phosphate ester. In many microorganisms, sugars are transported precisely in this manner. The energy source in this case is phosphoenolpyruvate (The energy released during The conversion of PEP into Pyruvate is utilized to drive the transport processes).

Transport processes coupled with the conversion of a substrate (such as glucose) into substrate derivatives (glucose-6-phosphate) are referred to as translocation processes. In E. coli, glucose, fructose, mannose, and mannitol are transported in this way, whereas in Staphylococcus aureus, lactose and other Disaccharides are handled similarly. However, the phosphotransferase sugar transport system is not characteristic of all Bacteria. Many of them (primarily aerobes) utilize an active transport system for glucose uptake. The phosphotransferase system Functions predominantly in facultative and strict anaerobes. For anaerobes, this system is of great importance as it allows them to conserve ATP.

There is evidence that purine and pyrimidine bases are also transported via group translocation.