Engineering of Surface Display Systems in E. coli for Recombinant Protein Production.

Isolation of various groups of protein preparations is a crucial task in many areas of biochemical research. Creating an effective, simple and economically feasible system for recombinant protein production is highly valuable for both basic research and applied biotechnology. Most laboratory studies focus on bacterial systems for heterologous gene expression. However, such systems can encounter major difficulties with target proteins that have specific properties. Some proteins can aggregate, form insoluble inclusion bodies or undergo proteolytic cleavage during overproduction. Moreover, they can be toxic, and thus adversely affect the host cell when overproduced. These issues can be circumvented by using cellular secretion systems to export the target protein from the cell during production. The present study compares three established systems for exporting target proteins to the bacterial cell surface. Three model proteins were selected: the cytokine IL-17A, the catalytic domain of TEV protease, and the calcium-binding domain of nucleobindin 1. Three protein export systems were used: the first was based on the E. coli outer membrane OmpA protein, the second on the E. coli Ag43 autotransporter of the AIDA-I family, and the third on the INP of Pseudomonas syringae. Recombinant proteins were cleaved by site-directed chemical proteolysis.