Novel surface display system for heterogonous proteins on Lactobacillus plantarum

Abstract

To establish a novel cell surface display system that would enable the display of target proteins on Lactobacillus plantarum. BlastP analysis of the amino acids sequence data revealed that the N-terminus of the putative muropeptidase MurO from L. plantarum contained two putative lysin motif (LysM) repeat regions, implying that the MurO was involved in bacterial cell wall binding. To investigate the potential of MurO for surface display, green fluorescent protein (GFP) was fused to MurO at its C-terminus and the resulting fusion protein was expressed in Escherichia coli. After being mixed with L. plantarum cells in vitro, GFP was successfully displayed on the surfaces of L. plantarum cells. Increases in the fluorescence intensities of chemically pretreated L. plantarum cells compared to those of nonpretreated cells suggested that the peptidoglycan was the binding ligand for MurO. SDS sensitivity assay showed that the GFP fluorescence intensity was reduced after being treated with SDS. To demonstrate the applicability of the MurO-mediated surface display system, β-galactosidase from Bifidobacterium bifidium, in place of GFP, was functionally displayed on the surface of L. plantarum cells via MurO. The MurO was a novel anchor protein for constructing a surface display system for L. plantarum. The success in surface display of GFP and β-galactosidase opened up the feasibility of employing the cell wall anchor of MurO for surface display in L. plantarum.