Plasmid amplification in Escherichia coli after temperature upshift is impaired by induction of recombinant protein synthesis

Production of recombinant proteins often interferes with the physiology of the host organism by causing stress responses. In recombinant Escherichia coli, the cellular content of ColE1-derived plasmids and, consequently, the synthesis of the constitutively synthesized plasmid-encoded proteins generally increases after a temperature upshift. Simultaneous induction of inducible recombinant proteins that are synthesized at high levels and tend to form inclusion bodies, however, attenuates the plasmid amplification. This phenomenon was observed using temperature- as well as IPTG-inducible expression systems. Thus, high-level recombinant gene expression in connection with inclusion body formation does not only interfere with host cell but also with plasmid-related functions.