Expression system in microorganism and its use for expressing heterologous and homologous proteins

摘要

The present invention concerns the discovery of a new regulatory mechanism for gene expression in lactic acid bacteria (LAB), especially Lactobacillus sake LTH673 or Lactobacillus plantarium C11, that includes previously unrecognized strongly regulable promoter elements. The essential finding is that the expression of genes under the control of a promoter element dependent on the expression of the IF-K-R gene cluster. The expression of the IF-K-R gene cluster is autoinduced by the secreted peptide encoded by IF, thus providing a regulable expression system for a desired protein. The invention further comprises the purified IF protein.