Abstract
英文摘要 The development of protein secretion systems suitable for use in innocuous lactic acid bacteria could enable these microorganisms to be used for the production by secretion of a number of heterologous proteins. Provided that suitable methods for protein recovery are available, higher initial levels of purity can be obtained when a product is secreted. Staphylococcal nuclease (Nuc protein) is a small, stable, biochemically well-characterized enzyme secreted by numerous gram-positive bacteria.Plasmid pNuc10 encoding LEISSTCDA-NucT is a gram-positive bacteria-cloning vector. The secretion efficiency of proteins fused to the Nuc signal peptide can be improved by the presence of the LEISSTCDA propeptide. In this study, the VP1 peptide of enterovirus 71 was fused with glutathione S-transferase as a heterologous protein. Before introducing of VP1-GST gene into pNuc10, we construct a shuttle vector pBN by fusing vector pBluescript with pNuc10, thus cloning of VP1-GST gene into the site between LEISSTCDA-NucT could be established in E.coli. The VP1-GST expression plasmid is then transferred to the Lactococcus lactis expression strain by electroporation. We hope that the L. lactis transformed with this vector can be used as a life vaccine system.