Download MendeleyIdentification of difructose dianhydride I synthase/hydrolase from an oral bacterium establishes a novel glycoside hydrolase family.
Kashima, T., Okumura, K., Ishiwata, A., Kaieda, M., Terada, T., Arakawa, T., Yamada, C., Shimizu, K., Tanaka, K., Kitaoka, M., Ito, Y., Fujita, K., Fushinobu, S.(2021) J Biol Chem 297: 101324-101324
- PubMed: 34688653
- DOI: https://doi.org/10.1016/j.jbc.2021.101324
- Primary Citation of Related Structures:
7V1V, 7V1W, 7V1X - PubMed Abstract:
Fructooligosaccharides and their anhydrides are widely used as health-promoting foods and prebiotics. Various enzymes acting on β-D-fructofuranosyl linkages of natural fructan polymers have been used to produce functional compounds. However, enzymes that hydrolyze and form α-D-fructofuranosyl linkages have been less studied. Here, we identified the BBDE_2040 gene product from Bifidobacterium dentium (α-D-fructofuranosidase and difructose dianhydride I synthase/hydrolase from Bifidobacterium dentium [αFFase1]) as an enzyme with α-D-fructofuranosidase and α-D-arabinofuranosidase activities and an anomer-retaining manner. αFFase1 is not homologous with any known enzymes, suggesting that it is a member of a novel glycoside hydrolase family. When caramelized fructose sugar was incubated with αFFase1, conversions of β-D-Frup-(2→1)-α-D-Fruf to α-D-Fruf-1,2':2,1'-β-D-Frup (diheterolevulosan II) and β-D-Fruf-(2→1)-α-D-Fruf (inulobiose) to α-D-Fruf-1,2':2,1'-β-D-Fruf (difructose dianhydride I [DFA I]) were observed. The reaction equilibrium between inulobiose and DFA I was biased toward the latter (1:9) to promote the intramolecular dehydrating condensation reaction. Thus, we named this enzyme DFA I synthase/hydrolase. The crystal structures of αFFase1 in complex with β-D-Fruf and β-D-Araf were determined at the resolutions of up to 1.76??. Modeling of a DFA I?molecule in the active site and mutational analysis also identified critical residues for catalysis and substrate binding. The hexameric structure of αFFase1 revealed the connection of the catalytic pocket to a large internal cavity via a channel. Molecular dynamics analysis implied stable binding of DFA I?and inulobiose to the active site with surrounding water molecules. Taken together, these results establish DFA?I?synthase/hydrolase as a member of a new glycoside hydrolase family (GH172).
Organizational Affiliation:
Department of Biotechnology, The University of Tokyo, Tokyo, Japan.
