Construction of a bacterial surface display system using split green fluorescent protein (GFP) in Escherichia coli.

The cell surface display system employs carrier proteins to present target proteins on the outer membrane of cells. This system enables functional proteins to be exposed on the exterior of living cells without cell lysis, allowing direct interaction with the surrounding environment. A major limitation of conventional approaches is the difficulty in displaying large-sized enzymes or antibodies, despite their critical roles in applications requiring functional domains that must remain intact, such as catalytic or antigen-binding sites. To address this challenge, we developed a novel system that enables the surface presentation of target proteins in Escherichia coli by integrating the cell surface display system with the self-assembly of split green fluorescent proteins (GFPs). In this system, GFP11M3 was fused to the carrier protein Lpp-OmpA and displayed on the bacterial surface. The surface-localized Lpp-OmpA-GFP11M3 subsequently assembled with GFP1-10opt, forming a functional GFP complex. By conjugating other target proteins, such as enzymes or antibodies, to GFP1-10opt, these biomolecules can be efficiently displayed on the cell surface. This approach not only facilitates the presentation of large biomolecules but also enables real-time visualization of protein localization through fluorescence detection.