Engineering the Effector Domain of the Artificial Transcription Factor to Improve Cellulase Production byTrichoderma reesei

Filamentous fungal strains ofTrichoderma reeseihave been widely used for cellulase production, and great effort has been devoted to enhancing their cellulase titers for the economic biorefinery of lignocellulosic biomass. In our previous studies, artificial zinc finger proteins (AZFPs) with the Gal4 effector domain were used to enhance cellulase biosynthesis inT. reesei, and it is of great interest to modify the AZFPs to further improve cellulase production. In this study, the endogenous activation domain from the transcription activator Xyr1 was used to replace the activation domain of Gal4 of the AZFP to explore impact on cellulase production. The cellulase producerT. reeseiTU-6 was used as a host strain, and the engineered strains containing the Xyr1 and the Gal4 activation domains were named asT. reeseiQS2 andT. reeseiQS1, respectively. Compared toT. reeseiQS1, activities of filter paper and endoglucanases in crude cellulase produced byT. reeseiQS2 increased 24.6 and 50.4%, respectively. Real-time qPCR analysis also revealed significant up-regulation of major genes encoding cellulase inT. reeseiQS2. Furthermore, the biomass hydrolytic performance of the cellulase was evaluated, and 83.8 and 97.9% more glucose was released during the hydrolysis of pretreated corn stover using crude enzyme produced byT. reeseiQS2, when compared to the hydrolysis with cellulase produced byT. reeseiQS1 and the parent strainT. reeseiTU-6. As a result, we proved that the effector domain in the AZFPs can be optimized to construct more effective artificial transcription factors for engineeringT. reeseito improve its cellulase production.