Fungal β-Glycosidase Belonging to Subfamily 4 of Glycoside Hydrolase Family 30 with Transglycosylation Activity.

Fomitopsis palustris, a prominent wood decayer, is known to produce a variety of glycoside hydrolases (GHs). In this study, we characterized a fungal β-glycosidase belonging to subfamily 4 of GH family 30 (GH30). The recombinant protein (FpGH30) showed the highest hydrolytic activity toward p-nitrophenyl-β-d-fucopyranoside (pNPβFuc), followed by p-nitrophenyl-α-l-arabinopyranoside (pNPαAra) and p-nitrophenyl-β-d-galactopyranoside (pNPβGal). FpGH30 also exhibited transglycosylation activities, which catalyzed the transfer of glycosyl moieties to different glycosides and alkyl alcohols. When pNPβFuc, pNPβGal, and pNPαAra were used as substrates, self-condensation reactions occurred, leading to the production of the corresponding transglycosylated products with yields of 21, 26, and 25%, respectively. The enzyme was also able to catalyze the transfucosylation of pNP derivatives of β-d-glucose, β-d-mannose, and β-d-xylose and alkyl alcohols (C1-C6), producing the corresponding transfucosylated products and alkyl fucosides. Our study indicates that FpGH30 is the first characterized fungal β-glycosidase belonging to subfamily 4 of GH30 with transglycosylation activities.