CELL-WALL ANCHORING OF THE STREPTOCOCCUS-PYOGENES M6 PROTEIN IN VARIOUS LACTIC-ACID BACTERIA

The M6 protein from Streptococcus pyogenes is the best-characterized m ember of a family of cell envelope-associated proteins. Based on the o bservation that the C-terminal sorting signals of these proteins can d rive cell wall anchoring of heterologous unanchored proteins, we have cloned and expressed the emm6 structural gene for the M6 protein in va rious lactic acid bacteria (LAB). The emm6 gene was successfully expre ssed from lactococcal promoters in several Lactococcus lactis strains, an animal-colonizing Lactobacillus fermentum strain, Lactobacillus sa ke, and Streptococcus salivarius subsp. thermophilus. The M6 protein w as efficiently anchored to the cell wall in all strains tested, In lac tobacilli, essentially all detectable MG protein was cell wall associa ted, These results suggest the feasibility of using the C-terminal anc hor moiety: of M6 for protein surface display in LAB.