Development of a Highly Efficient Protein-Secreting System in RecombinantLactobacillus casei

摘要

The available techniques for heterologous protein secretionin Lactobacillus strains are limited. The aim of the presentstudy was to develop an efficient protein-secretion systemusing recombinant lactobacilli for various applicationssuch as live delivery of biotherapeutics. For the constructionof expression vectors, the Lactobacillus brevis slpA promoter,Lactobacillus casei prtP signal sequence, and mouse IL-10sequences were used as a model system. Interestingly, theslpA promoter exhibited strong activity in L. casei, contraryto previous observations. In order to stabilize replicationof the plasmid in E. coli, a removable terminator sequencewas built into the promoter region. For the improvementof secretion efficiency, a DTNSD oligopeptide was addedto the cleavage site of signal peptidase. The resultingplasmids provided remarkably efficient IL-10 secretion.Accumulation of the protein in the culture supernatantvaried widely according to the pH conditions. By analysisof the secreted protein, formation of homodimers, andbiological activity, IL-10 was confirmed to be functional.The presently constructed plasmids could be useful toolsfor heterologous protein secretion in L. casei.