CELL-SURFACE DISPLAY OF RECOMBINANT PROTEINS ON STAPHYLOCOCCUS-CARNOSUS

A novel expression system for surface display of heterologous proteins on Staphylococcus carnosus cells has been developed. Taking advantage of the promoter and secretion signals, including a propeptide region, from the lipase gene of Staphylococcus hyicus and the cell wall-spann ing and membrane-binding region of protein A from Staphylococcus aureu s, efficient surface display of an 80-amino-acid peptide from a malari a blood stage antigen could be achieved. A serum albumin binding prote in from streptococcal protein G was used both as a general reporter mo lecule and to increase the accessibility of the surface-displayed prot eins. Immunoblotting, immunogold staining, and immunofluorescence on i ntact recombinant S. carnosus cells verified the presence of the prope ptide, the malaria antigen, and the albumin-binding reporter protein o n the bacterial surface. For the first time, fluorescence-activated ce ll sorting was used to analyze the presence of surface-displayed hybri d receptors on gram-positive bacteria.