Upstream strategies to minimize proteolytic degradation upon recombinant production in Escherichia coli.

Proteolytic degradation of recombinant proteins represents a major problem related to production of gene products in heterologous hosts. Recombinant DNA technology offers several alternative strategies for stabilization of expressed gene products. These strategies can often give dramatic stabilization effects and can be combined with strategies involving optimization of fermentation conditions or downstream processing schemes. In this review, various genetic approaches to improve the stability of recombinant proteins will be discussed, including (i) choice of host cell strain, (ii) product localization, (iii) use of gene fusion partners, and (iv) product engineering. In addition, the solubility of the gene product can be influenced by factors such as growth temperature, promoter strength, fusion partners, and site-directed changes. Altogether, a battery of approaches can be used to obtain stable gene products.