中国生物工程杂志

The methylotrophic yeast, Pichia pastoris, has been one of most widely used expression system for heterologous proteins production in the past decades. In this review, we mainly focus on the influences of methanol utilization phenotypes (i.e Mut+, MutS and Mut-) and gene dosage on recombinant protein expression in genetically engineered Pichia pastoris. Strains with different phenotype not only exhibit different methanol utilization rate and growth rate, but also differ in terms of foreign protein production and byproducts production. Gene dosage has a complex impact on heterologous protein expression. Foreign gene copy number could positively correlate to protein production, whereas the negative correlation often occurs especially when gene dosage goes high. The latter might be related with post-translational processing of target protein like disulfide bond formation, folding, etc and some studies show that protein production yield can be enhanced by co-expression of proteins with chaperon activity, like PDI(protein disulfide isomerise). Physiologic profiles of strains with different gene dosage were also compared.