Characterization of a new beta(1-3)-glucan branching activity of Aspergillus fumigatus

J Biol Chem. 2010 Jan 22;285(4):2386-96. doi: 10.1074/jbc.M109.077545. Epub 2009 Nov 30.


A new HPLC method was developed to separate linear from beta(1-6)-branched beta(1-3)-glucooligosaccharides. This methodology has permitted the isolation of the first fungal beta(1-6)/beta(1-3)-glucan branching transglycosidase using a cell wall autolysate of Aspergillus fumigatus (Af). The encoding gene, AfBGT2 is an ortholog of AfBGT1, another transglycosidase of A. fumigatus previously analyzed (Mouyna, I., Hartland, R. P., Fontaine, T., Diaquin, M., Simenel, C., Delepierre, M., Henrissat, B., and Latgé, J. P. (1998) Microbiology 144, 3171-3180). Both enzymes release laminaribiose from the reducing end of a beta(1-3)-linked oligosaccharide and transfer the remaining chain to another molecule of the original substrate. The AfBgt1p transfer occurs at C-6 of the non-reducing end group of the acceptor, creating a kinked beta(1-3;1-6) linear molecule. The AfBgt2p transfer takes place at the C-6 of an internal group of the acceptor, resulting in a beta(1-3)-linked product with a beta(1-6)-linked side branch. The single Afbgt2 mutant and the double Afbgt1/Afbgt2 mutant in A. fumigatus did not display any cell wall phenotype showing that these activities were not responsible for the construction of the branched beta(1-3)-glucans of the cell wall.

MeSH terms

  • Aspergillus fumigatus / enzymology*
  • Aspergillus fumigatus / genetics
  • Blotting, Western
  • Cell Wall / enzymology
  • Cellulases / metabolism
  • Chromatography, High Pressure Liquid / methods
  • Electrophoresis, Polyacrylamide Gel
  • Fungal Proteins / genetics
  • Fungal Proteins / isolation & purification
  • Fungal Proteins / metabolism
  • Gas Chromatography-Mass Spectrometry
  • Glucan Endo-1,3-beta-D-Glucosidase / genetics
  • Glucan Endo-1,3-beta-D-Glucosidase / isolation & purification*
  • Glucan Endo-1,3-beta-D-Glucosidase / metabolism*
  • Glycosylation
  • Mutation
  • Nuclear Magnetic Resonance, Biomolecular
  • Phenotype
  • beta-Glucans / isolation & purification*
  • beta-Glucans / metabolism*


  • Fungal Proteins
  • beta-Glucans
  • Cellulases
  • Glucan Endo-1,3-beta-D-Glucosidase