High-level expression of a novel multifunctional GH3 family β-xylosidase/α-arabinosidase/β-glucosidase from Dictyoglomus turgidum in Escherichia coli

A novel beta-xylosidase Dt-2286 from Dictyoglomus turgidum was cloned and overexpressed in Escherichia coli BL21 (DE3). Dt-2286 belonging to glycoside hydrolase (GH) family 3 encodes a polypeptide with 762 amino acid residues with a molecular weight of 85.1 kDa. By optimization of the growth and induction conditions, the activity of beta-xylosidase reached 273 U/mL, which is the highest yield reported to date from E. coli in a shakeflask. The optimal activities of the purified Dt-2286 were found at pH 5.0 and 98 degrees C. It also shows excellent thermostable/haloduric/organic solvent-tolerance. Dt-2286 was revealed to be a multifunctional enzyme with beta-xylosidase, alpha-arabinofuranoside, alpha-arabinopyranoside and beta-glucosidase activities, and Kcat/Km was 5245.316 mM(-1) s(-1), 2077.353 mM(-1) s(-1), 1626.454 mM(-1) s(-1), and 470.432 mM(-1) s(-1) respectively. Dt-2286 showed significant synergistic effects on the degradation of xylans, releasing more reduced sugars (up to 15.08 fold) by simultaneous addition with endoxylanase. Moreover, this enzyme has good activity in the hydrolysis of epimedium B, demonstrating its versatility in practical applications.

Automated summary

The novel beta-xylosidase Dt-2286 from Dictyoglomus turgidum showed high yield and excellent thermostability, as well as multifunctionality and good synergistic effects, making it suitable for various practical applications.