Bicistronic design as recombinant expression enhancer: characteristics, applications, and structural optimization

The bicistronic design (BCD) is characterized by a short fore-cistron sequence and a second Shine-Dalgarno (SD2) sequence upstream of the target gene. The outstanding performance of this expression cassette in promoting recombinant protein production has attracted attention. Recently, the application of the BCD has been further extended to gene expression control, protein translation monitoring, and membrane protein production. In this review, we summarize the characteristics, molecular mechanisms, applications, and structural optimization of the BCD expression cassette. We also specifically discuss the challenges that the BCD system still faces. This is the first review of the BCD expression strategy, and it is believed that an in-depth understanding of the BCD will help researchers to better utilize and develop it. KEY POINTS: • Summary of the characteristics and molecular mechanisms of the BCD system. • Review of the actual applications of the BCD expression cassette. • Summary of the structural optimization of the BCD system.