Crystal structure of a β-fructofuranosidase with high transfructosylation activity from Aspergillus kawachii

Abstract

β-Fructofuranosidases belonging to glycoside hydrolase family (GH) 32 are enzymes that hydrolyze sucrose. Some GH32 enzymes also catalyze transfructosylation to produce fructooligosaccharides. We found that Aspergillus kawachii IFO 4308 β-fructofuranosidase (AkFFase) produces fructooligosaccharides, mainly 1-kestose, from sucrose. We determined the crystal structure of AkFFase. AkFFase is composed of an N-terminal small component, a β-propeller catalytic domain, an α-helical linker, and a C-terminal β-sandwich, similar to other GH32 enzymes. AkFFase forms a dimer, and the dimerization pattern is different from those of other oligomeric GH32 enzymes. The complex structure of AkFFase with fructose unexpectedly showed that fructose binds both subsites -1 and +1, despite the fact that the catalytic residues were not mutated. Fructose at subsite +1 interacts with Ile146 and Glu296 of AkFFase via direct hydrogen bonds.

Structural insights into polysaccharide recognition by Flavobacterium johnsoniae dextranase, a member of glycoside hydrolase family 31

“…It is unclear whether the two α‐glucose molecules were independently present at both subsites −2 and −1 or whether isomaltose was present as a contaminant in the glucose solution. Similar observations have been reported on GH6 cellobiohydrolases in complex with cellobiose (modeled as cellotriose and cellotetraose) and a GH32 β‐fructofuranosidase in complex with fructose (modeled as fructosylfructose) . GH31 enzymes are retaining glycosidases, and a pair of Asp residues have been identified to be catalytic residues .…”

Highly porous core–shell chitosan beads with superb immobilization efficiency forLactobacillus reuteri121 inulosucrase and production of inulin-type fructooligosaccharides

“…Aspergillus aculeatus, 8,9 Aspergillus awamori, 10 Aspergillus kawachii, 11 and Aspergillus oryzae. 12 Nonetheless, the use of fungal enzymes had been shown to have some limitations because they prefer hydrolysis to transfructosylation, and most of the fungal enzymes specically synthesize only a short chain of IFOS with a degree of polymerization (DP) in the range of 2-4.…”

Purification and characterization of an invertase and a transfructosylase from Aspergillus terreus

“…This enzyme was seen to be composed of an N‐terminal small component, a β‐propeller catalytic domain, an α‐helical linker, and a C‐terminal β‐sandwich. Besides, it was observed that the enzyme, like invertase 2 from A. terreus , forms a dimer (Nagaya et al, ).…”