Phosphorylation and metabolism of sucrose and its five linkage-isomeric α- d-glucosyl- d-fructoses by Klebsiella pneumoniae

Abstract

Not only sucrose but the five isomeric α- d-glucosyl- d-fructoses trehalulose, turanose, maltulose, leucrose, and palatinose are utilized by Klebsiella pneumoniae as energy sources for growth, thereby undergoing phosphorylation by a phosphoenolpyruvate-dependent phosphotransferase system uniformly at O-6 of the glucosyl moiety. Similarly, maltose, isomaltose, and maltitol, when exposed to these conditions, are phosphorylated regiospecifically at O-6 of their non-reducing glucose portion. The structures of these novel compounds have been established unequivocally by enzymatic analysis, acid hydrolysis, FAB negative-ion spectrometry, and 1H and 13C NMR spectroscopy. In cells of K. pneumoniae, hydrolysis of sucrose 6-phosphate is catalyzed by sucrose 6-phosphate hydrolase from Family 32 of the glycosylhydrolase superfamily. The five 6′-O-phosphorylated α- d-glucosyl-fructoses are hydrolyzed by an inducible (∼49–50 Kda) phospho-α-glucosidase from Family 4 of the glycosylhydrolase superfamily.