Heterologous Expression of Proteins in Trichoderma

The main constituents for expressing heterologous gene products in Trichoderma reesei are the strong inducible cellobiohydrolase 1 (cbh1) promoter, high protein-secreting mutant strains and the heterologous protein typically fused to an endogenous well-secreted carrier protein. Despite of several variations to the tools of the trade, surprisingly little progress has been made over the last 20 years in terms of the yields of heterologous gene products produced in fungi. While recent approaches, including genome sequencing and transcriptional and proteomic studies, have provided some leads for further development, there seems to be additional physiological factors that would need to be addressed in order to better understand and overcome the bottlenecks of production of heterologous proteins in T. reesei. Here we discuss the various approaches and recent advancements into protein expression in this industrially exploited production host.