Metabolism of sucrose and its five linkage-isomeric alpha-D-glucosyl-D-fructoses by Klebsiella pneumoniae. Participation and properties of sucrose-6-phosphate hydrolase and phospho-alpha-glucosidase

J Biol Chem. 2001 Oct 5;276(40):37415-25. doi: 10.1074/jbc.M106504200. Epub 2001 Jul 25.


Klebsiella pneumoniae is presently unique among bacterial species in its ability to metabolize not only sucrose but also its five linkage-isomeric alpha-d-glucosyl-d-fructoses: trehalulose, turanose, maltulose, leucrose, and palatinose. Growth on the isomeric compounds induced a protein of molecular mass approximately 50 kDa that was not present in sucrose-grown cells and which we have identified as an NAD(+) and metal ion-dependent 6-phospho-alpha-glucosidase (AglB). The aglB gene has been cloned and sequenced, and AglB (M(r) = 49,256) has been purified from a high expression system using the chromogenic p-nitrophenyl alpha-glucopyranoside 6-phosphate as substrate. Phospho-alpha-glucosidase catalyzed the hydrolysis of a wide variety of 6-phospho-alpha-glucosides including maltose-6'-phosphate, maltitol-6-phosphate, isomaltose-6'-phosphate, and all five 6'-phosphorylated isomers of sucrose (K(m) approximately 1-5 mm) yet did not hydrolyze sucrose-6-phosphate. By contrast, purified sucrose-6-phosphate hydrolase (M(r) approximately 53,000) hydrolyzed only sucrose-6-phosphate (K(m) approximately 80 microm). Differences in molecular shape and lipophilicity potential between sucrose and its isomers may be important determinants for substrate discrimination by the two phosphoglucosyl hydrolases. Phospho-alpha-glucosidase and sucrose-6-phosphate hydrolase exhibit no significant homology, and by sequence-based alignment, the two enzymes are assigned to Families 4 and 32, respectively, of the glycosyl hydrolase superfamily. The phospho-alpha-glucosidase gene (aglB) lies adjacent to a second gene (aglA), which encodes an EII(CB) component of the phosphoenolpyruvate-dependent sugar:phosphotransferase system. We suggest that the products of the two genes facilitate the phosphorylative translocation and subsequent hydrolysis of the five alpha-d-glucosyl-d-fructoses by K. pneumoniae.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / isolation & purification
  • Base Sequence
  • Biological Transport
  • Cloning, Molecular
  • DNA, Bacterial / analysis
  • Escherichia coli / enzymology
  • Fructose / chemistry
  • Glycoside Hydrolases / metabolism*
  • Hydrolysis
  • Klebsiella pneumoniae / enzymology
  • Klebsiella pneumoniae / genetics
  • Klebsiella pneumoniae / metabolism*
  • Metals / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Isoforms / metabolism
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Substrate Specificity
  • Sucrose / metabolism*
  • alpha-Glucosidases / genetics*
  • alpha-Glucosidases / isolation & purification
  • alpha-Glucosidases / metabolism
  • beta-Fructofuranosidase


  • Bacterial Proteins
  • DNA, Bacterial
  • Metals
  • Protein Isoforms
  • Fructose
  • Sucrose
  • Glycoside Hydrolases
  • maltose-6'-phosphate glucosidase
  • alpha-Glucosidases
  • beta-Fructofuranosidase

Associated data

  • GENBANK/AF377881