Comparison of the Efficiency of Phage Coat Proteins Displaying Exogenous Proteins

Abstract Background: Filamentous phage display has emerged as a common method for protein engineering, including the manipulation of antibody fragments. Various capsid proteins, such as gene III protein P3 (P3), truncated P3 (TP3), VIII protein P8, and IX protein P9, have been employed to display foreign proteins. Despite their widespread use, comprehensive comparative analyses of their display performances remain scarce. Methods: Six foreign proteins, ranging from 8 to 520 residues in length, were fused to phagemid-borne proteins P3, TP3, P8, and P9. Phage titers of the phage supernatants were quantified to estimate phage yields. Phage ELISA experiments were conducted to detect the Flag signals of the displayed proteins and assess their display ability. Additionally, phage ELISA experiments were performed to evaluate the binding ability of the fusion proteins. Both helper phages M13KO7 and DeltaPhage were investigated for the P9 system to compare their effects on the display efficiency of foreign proteins. Results: Among the four phage display systems, the P3 system demonstrated efficient display of foreign proteins of varying lengths without altering their binding properties. The TP3 system efficiently displayed small foreign proteins but showed a slight reduction in their binding properties. The P8 system exhibited characteristics similar to the TP3 system, albeit with a significantly lower phage titer. The P9 system, when associated with M13KO7, displayed small proteins effectively, while DeltaPhage enhanced the display efficiency of foreign proteins fused with this system. Conclusions: These findings not only highlight the superiority of the P3 system among the tested display systems but also contribute to our understanding of selecting appropriate display systems for showcasing different proteins.