Escherichia coli phosphorylates 1,5-Anhydroglucitol and releases 1,5-Anhydroglucitol 6-phosphate when glucose is absent in the medium.

The cyclic polyol 1,5-anhydro-D-glucitol (AG) is detected in most organisms, but little is known about its metabolism and physiological roles. Our previous study demonstrated that Escherichia coli C600 synthesizes AG when glucose is exhausted in the medium and that it temporarily releases AG into and then takes it back from the medium, thus forming a sharp peak in AG concentration in the medium a few hours after reaching stationary growth phase. The present study demonstrates that when glucose is absent in the culture medium, E. coli C600 takes up and phosphorylates AG and releases a large portion of it back into the medium in the form of a phosphate ester. [U-13C]AG was added to the medium after the exhaustion of glucose and the resulting [U-13C]AG phosphate was partially purified by several steps of anion exchange chromatography and identified as AG 6-phosphate by 13C-NMR. The identity of the phosphate ester was also confirmed by GC-MS analysis after further purification.