Bacterial signal peptides: structure, optimization, and applications

Abstract

Bacterial signal peptides are N-terminal tags that direct proteins for export through one of various transport pathways. These signal peptides are highly important as they are the key determinants of transport, ensuring that the correct protein ends up at the correct pathway. While these peptides consist of three domains with well conserved biochemical properties, there still remains a large amount of diversity between the signal sequences for different proteins, transport pathways, and bacterial species. Recent advancements have allowed us to predict signal sequences and manipulate them in an attempt to optimize export efficiency. This knowledge can then be exploited in the field of recombinant protein production wherein bacterial species can be used to produce and secrete proteins of interest. By fusing the protein with an optimized signal peptide, the yield or rate of export can be improved. This review focuses on signal peptides for two primary transport pathways (Sec and Tat) in E. coli specifically, with an emphasis on applications and the production of recombinant proteins.