Cloning and characterization of a novel bifunctional acetyl xylan esterase with carbohydrate binding module from Phanerochaete chrysosporium

The cDNA of acetyl xylan esterase 2 (PcAxe2) gene containing a carbohydrate binding module (CBM) sequence from Phanerochaete chrysosporium was cloned and expressed in Pichia pastoris. The recombinant PcAxe2 protein (rPcAxe2) was efficiently produced, reaching a maximum of 1058 U l(-1) after 6 days of cultivation. Molecular mass of the rPcAxe2 on SDS-PAGE was approximately 63 kDa under hyperglycosylation. Optimal activity of the purified rPcAxe2 enzyme was observed at pH and temperature of 7.0 and 30-35 degrees C, respectively. In addition to acetyl xylan esterase activity, rPcAxe2 also exhibited a xylanase activity at an optimum pH and temperature of 5.0 and 80 degrees C, respectively. The synergistic action of rPcAxe2 with rPcXynC on birchwood xylan, beechwood xylan and wheat arabinoxylan enhanced the total reducing soluble sugar. (c) 2012, The Society for Biotechnology, Japan. All rights reserved.