Improvement of the cellulolytic activity of Trichoderma reesei endoglucanase IV with an additional catalytic domain

The modular structure of the T. reesei endoglucanase IV (EGIV) was reconstructed by fusing EGIV with an additional catalytic module (EGIV-CM). The genes eg4 and eg4-cm were obtained through RT-PCR and gene fusion, and were respectively expressed in recombinant Pichia strains (P. pastoris EGIV1 and P. pastoris EGIV-CM1). The CMC activities of cultivation supernatant of P. pastoris EGIV1 and P. pastoris EGIV-CM1 were 2.4 U/ml and 4.3 U/ml, respectively. Modification of the EGIV structure with an additional catalytic module improved the specific activity about 4-fold.