Fig. 4
Effects of single folding factor overexpression on antibody secretion. A heatmap representing the change in specific product yield of each strain relative to the strain background. The colors and numbers in each cells represent the fold-change that the specific promoter gene combination had on the specific product yield. CPR5 overexpression yielded the most beneficial impact. The values are for wild-type yeast strains grown at 30 °C and for 0.5 % galactose induction (a) and Δopi1 strains in the same conditions (b). c Temperature and type of promoter affect the effect of CPR5 on the specific product yield in wild-type. UPR-controlled promoters, PKAR2 and PPDI1, show an increase in the positive impact on antibody secretion with increasing temperature, as displayed by the trend line. The specific product yield of wild-type is included as comparison. The values are from measurements with 0.5 % galactose induction. d Promoter strengths measured by qPCR of CPR5 mRNA levels at 2 and 10 h after induction with 2 % galactose at 30 °C. Relative normalized expression is calculated as setting the CPR5 mRNA levels from wt as control. The promoters show different characteristics, as the UPR-inducible promoters follow the wt levels and PGAL1, PGPD and PTEF have higher initial mRNA amount