Stepwise Optimization of Inducible Expression System for the Functional Secretion of Horseradish Peroxidase in Saccharomyces cerevisiae

Horseradish peroxidase (HRP) is a plant-derived glycoprotein
that
can be developed as a food additive to cross-link proteins or biopolymers.
Although Saccharomyces cerevisiae has
advantages in the production of food-grade HRP, the low expressional
level and inefficient secretion hindered its application values. After
comparing the effects of constitutive and inducible expression on
cell growth, the strength of HRP expression was roughly tuned by replacing
core regions of the promoter in the GAL80-knockout
strain and further finely tuned by terminator screening. Additionally,
the most suitable signal peptide was selected, and the pre-peptide
with pro-peptides was modified to balance the transport of HRP in
the endoplasmic reticulum. The extracellular HRP activity of the best
strain reached 13 506 U/L at the fermenter level, 330-fold
higher than the previous result of 41 U/L in S. cerevisiae. The strategy can be applied to alleviate the inhibition of cell
growth caused by the expression of toxic proteins and improve their
secretion.