Biotechnology and Bioengineering, Vol.115, No.5, 1321-1330, 2018
Development of a temperature-responsive yeast cell factory using engineered Gal4 as a protein switch
Conflict between cell growth and product accumulation is frequently encountered in biosynthesis of secondary metabolites. Herein, a temperature-dependent dynamic control strategy was developed by modifying the GAL regulation system to facilitate two-stage fermentation in yeast. A temperature-sensitive Gal4 mutant Gal4M9 was created by directed evolution, and used as a protein switch in Delta GAL80 yeast. After EGFP-reported validation of its temperature-responsive induction capability, the sensitivity and stringency of this system in multi-gene pathway regulation was tested, using lycopene as an example product. When Gal4M9 was used to control the expression of P-GAL-driven pathway genes, growth and production was successfully decoupled upon temperature shift during fermentation, accumulating 44% higher biomass and 177% more lycopene than the control strain with wild-type Gal4. This is the first example of adopting temperature as an input signal for metabolic pathway regulation in yeast cell factories.
Keywords:directed evolution;Gal4;lycopene;protein switch;temperature-dependent dynamic control;two-stage fermentation