Figure 6.

Overview of biological process overrepresented in Aspergillus nidulans recombinant strains. Heterologous protein production remains a complex process with some bottlenecks. Generally, the recombinant gene contains strong promoter for high level expression of the target mRNA. Large quantities of mRNAs overload the translational pathway, which increase misfolded proteins amounts in ER, inducing an ER stress (1). The homeostasis maintenance is achieved by UPR that induces genes coding to chaperones, amino acid metabolism, ribosome biogenesis, translation, among others (2). Furthermore, energy demand required for heterologous protein production increased (3), resulting in high levels of reactive oxygen species in the cell (4). The secretome analysis of recombinant strains showed the downregulation of biomass‐degrading enzymes and their genes, suggesting the presence of the RESS mechanism. Associated with the overload of misfolded proteins in the ER, this mechanism downregulates transcriptional activators, such as amyR and xlnR that regulates expression of several amylases and CAZymes respectively (5). The heat maps (at the bottom) represent the protein abundance in the recombinant (Anid_AbfA; Anid_Cbhl) and control strains (Anid_pEXPYR) in each biological process categorized by MIPS FunCat. The scale indicates the number of proteins found in each category.