Phosphorylation of Intracellular Fructose in Bacillus subtilis Mediated by Phosphoenolpyruvate‐l‐Fructose Phosphotransferase

Abstract

Intracellular fructose provided by the sorbitol pathway in B. subtilis is phosphorylated by the phosphoenolpyruvate-1-fructose phosphotransferase which is known to mediate a vectorial metabolism. The fate of this intracellular fructose was studied using mutants lacking the fructose 1-phosphate pathway or the fructose 6-phosphate pathway. It was shown that the phosphoenolpyruvate-dependent phosphorylation needs a prior exit of the sugar into the medium, this exit being probably catalyzed by a transport system. A low affinity intracellular phosphoenolpyruvate phosphotransferase system was found, which may be devoid of a physiological role.