Characterization of a recombinant multifunctional glycoside hydrolase family 3 β-xylosidase/α-l-arabinofuranosidase/β-glucosidase from Cellulosimicrobium cellulans sp. 21

• A new GH3 gene ccxyl3a was cloned from C. cellulans sp. 21 and heterologously expressed in E. coli.
• Enzyme CcXyl3A was a multifunctional enzyme with β-xylosidase/α-l-arabinofuranosidase/β-glucosidase activities.
• CcXyl3A synergistically acted with Thermomyces lanuginosus xylanase in beechwood xylan degradation.

A multifunctional β-xylosidase/α-l-arabinofuranosidase/β-glucosidase gene (ccxyl3a) belonging to glycoside hydrolase family 3 (GH3) was cloned from Cellulosimicrobium cellulans sp. 21 and expressed in Escherichia coli BL21 (DE3). The molecular mass of recombinant CcXyl3A was estimated to be approximately 95 kDa. With p-nitrophenyl-β-d-xyloside (pNPβXyl) as a substrate, the purified protein presented an optimal pH of 8.5 and an optimal temperature of 45 °C. Moreover, CcXyl3A was activated in the presence of the metals K+ and Na+. Purified CcXyl3A demonstrated multifunctional activities on pNPβXyl, p-nitrophenyl-β-d-glucoside (pNPβGlc), and p-nitrophenyl-α-l-arabinofuranoside (pNPαAraf). The greatest catalytic activity were found on pNPβXyl followed by pNPαAraf and pNPβGlc, respectively. Using xylooligosaccharides as substrate, CcXyl3A completely hydrolyzed xylobiose, xylotriose, xylotetraose and xylohexaose, xylose was the sole product. In addition, CcXyl3A synergistically acted with Thermomyces lanuginosus xylanase in the degradation of beechwood xylan, released xyloses from intermediate xylooligosaccharides produced by T. lanuginosus xylanase. To date, this is the first report to demonstrate the cloning and characterization of a multifunctional GH3 enzyme in C. cellulans that may have applications in hemicellulose degradation.

Figure optionsDownload as PowerPoint slide