ENHANCEMENT OF HETEROLOGOUS PROTEIN EXPRESSION IN ESCHERICHIA COLI BY CO-EXPRESSION OF NONSPECIFIC DNA-BINDING STRESS PROTEIN, DPS

Abstract

The over-expression of foreign proteins imposes metabolic burden on host strains that may lead to reduced cell growth and even yield of target heterologous protein. We investigated the effect of co-expression of nonspecific DNA-binding protein, Dps, one of the many stress proteins against oxidative damage and nutrient starvation, on the over-expression of heterologous protein in Escherichia coli expression system. It was observed that the co-expression of recombinant Dps reduced the growth rate in minimal M9 medium. On the contrary, Dps had a positive effect on cell growth in rich LB medium. It was also observed that Dps was capable of enhancing the specific production of insoluble target foreign protein, baculoviral polyhedrin (Polh) and green fluorescent protein (GFP) fusion in both media, demonstrating that the co-expression of Dps has general positive effects on foreign protein production regardless of medium types. Even though the mechanism of Dps on foreign protein production remains unclear, the ability for significant enhancement of target protein production (about 46% of target protein fraction in total cellular proteins and about 2.5-fold increase in product yield) may be successfully applied in practical culture process. (C) 2003 Elsevier Inc. All rights reserved.