New Approach to Achieve High-Level Secretory Expression of Heterologous Proteins by Using Tat Signal Peptide

The twin-arginine translocation (Tat) pathway is an attractive route for secretory production of heterologous proteins in E. coli. In this study, we investigated the potential use of Tat signal peptide from S. coelicolor to improve secretory expression. The results showed that Tat signal peptide (ssDagA) could effectively secrete active Green fluorescent protein (GFP) to periplasm. When the rare codons of signal sequence were optimized, the expression and secretion yield of GFP improved by about 2-3 folds as detected qualitatively by western blotting and fluorescent analysis. The increase of translation rate could be explained by the unstability of mRNA secondary structure. In summary, our strategy could provide a new approach for high-level secretory expression of heterologous proteins in E. coli.