Molecular dynamics simulation and experimental study of the surface-display of SPA protein via Lpp-OmpA system for screening of IgG

Staphylococcal protein A (SpA) is a major virulence factor of Staphylococcus aureus . S. aureus is able to escape detection by the immune system by the surface display of protein A. The SpA protein is broadly used to purify immunoglobulin G (IgG) antibodies. This study investigates the fusion ability of Lpp’-OmpA (46−159) to anchor and display five replicate domains of protein A with 295 residues length (SpA295) of S. aureus on the surface of Escherichia coli to develop a novel bioadsorbent.First, the binding between Lpp’-OmpA-SPA295 and IgGFc and the three-dimensional structure was investigated using molecular dynamics simulation. Then high IgG recovery from human serum by the surface-displayed system of Lpp’-OmpA-SPA295 performed experimentally. In silico analysiswas demonstrated the binding potential of SPA295 to IgG after expression on LPP-OmpA surface. Surface-engineered E. coli displaying SpA protein and IgG-binding assay with SDS-PAGE analysis exhibited high potential of the expressed complex on the E. coli surface for IgG capture from human serum which is applicable to conventional immune precipitation.