Method for quantitatively controlling plasmid copy number in antibiotic-free plasmid maintenance system

Abstract

The present invention relates to a gene expression cassette including a synthetic 5′ untranslated region (5′ UTR), a promoter, and a regulatory gene; a recombinant vector including a replication origin and the gene expression cassette; a recombinant microorganism which has the recombinant vector introduced thereinto and shows alleviated segregational instability and; a method for preparing a recombinant microorganism having alleviated segregational instability by introducing the recombinant vector thereinto; and a method for quantitatively controlling a plasmid copy number in a recombinant microorganism. According to the present invention, removal of infA and efp, which are genes indispensable for cells, encoding respectively for a translation initiation factor and a protein elongation factor (EF-P), from a microbial chromosome and introduction of the gene expression cassette including the regulatory gene with Escherichia coli serving as a host allow the stable maintenance of plasmids in an antibiotic-free medium without causing intercellular intrinsic variations. In addition, the precise control of expression levels of infA and efp in the recombinant microorganism by means of a promoter can lead to the quantitative control of PCN at high yield as well. Therefore, the present invention can find a broad spectrum of applications in a variety of industries producing recombinant proteins.

Dependencies are inferred from the claim text.