Development of a novel expression platform for heterologous protein production via deleting the p53-like regulator Vib1 in Trichoderma reesei

Trichoderma reesei is widely used as a protein production host due to its high natural capacity to secrete enzymes. Nonetheless, the complexity and abundance of secretome limit its extensive application in heterologous protein production. Here, a novel heterologous protein expression system with remarkable reduction of undesired background proteins was developed by deletion of the p53-like transcriptional factor Vib1. The vib1-deletion strain (Avib1) exhibited a dramatic decrease in cellulase and protease secretion, whereas the growth of Avib1 was comparable to that of the parental strain QM53, indicating that Avib1 possesses a great potential for heterologous protein production. Therefore, the Aspergillus niger fi-glucosidase-coding gene bglA was expressed in Avib1 and QM53 to demonstrate the feasibility of Avib1 as the protein production host. The bglA-expression strains QVB-1 (Avib1:bglA) and Q53B-1 (QM53:bglA) produced approximately 17.2 IU/mg and 14.7 IU/mg of fi-glucosidase activity, respectively. In addition, the fi-glucosidase activity in the supernatant of QVB-1 remained constant after 4-week incubation whereas that of Q53B-1 decreased by more than 60%. Furthermore, transcription levels of the genes involved in the unfolded protein response were relatively decreased in Avib1 compared with that in QM53, indicating the increased protein folding capacity of the endoplasmic reticulum in Avib1. These results demonstrate the feasibility of using T. reesei Avib1 as the host for heterologous protein production.