LamB as a carrier molecule for the functional exposition of IgG-binding domains of the Staphylococcus aureus Protein A at the surface of Escherichia coli K12

One, two or four IgG-binding domains of the Staphylococcus aureus Protein A (SPA) were inserted into the LamB protein which was expressed under control of the tac promoter. The chimeric proteins were shown to be exposed at the cell surface by analysis of isolated outer membranes and also by testing their functional interaction with IgG molecules. We hereby show that the LamB protein can accept as many as 232 amino acids (four SPA domains) and still be incorporated into the Escherichia coli outer membrane, while maintaining the functional conformation of the inserted SPA polypeptides.