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°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°C, respectively. The synergistic action of rPcAxe2 with rPcXynC on birchwood xylan, beechwood xylan and wheat arabinoxylan enhanced the total reducing soluble sugar.