Metabolism of gentiobiose in Aerobacter aerogenes

Cleavage of gentiobiose in cell extracts of gentiobiose-grown Aerobacter aerogenes was dependent on the presence of adenosine 5'-triphosphate (ATP). The enzymes that participate in the overall reaction were shown to be a beta-glucoside kinase, which catalyzes the phosphorylation of gentiobiose with ATP to form gentiobiose monophosphate [6-O-phosphoryl-beta-d-glucopyranosyl-(1 --> 6)-d-glucose], and a phospho-beta-glucosidase, which catalyzes the hydrolytic cleavage of gentiobiose monophosphate to form equimolar amounts of d-glucose and d-glucose 6-phosphate. Although the beta-glucoside kinase was previously shown to catalyze the phosphorylation of many beta-glucosides that serve as growth substrates (i.e., gentiobiose, cellobiose, cellobiitol, salicin, arbutin, methyl beta-d-glucoside, and phenyl beta-d-glucoside), mutant analysis and induction studies indicate that it functions only in the metabolism of gentiobiose, cellobiose, and cellobiitol.