Thermoinducible expression system for producing recombinant proteins in Escherichia coli: advances and insights

ABSTRACT Recombinant protein (RP) production from Escherichia coli has been extensively studied to find strategies for increasing product yields. The thermoinducible expression system is commonly employed at the industrial level to produce various RPs, which avoids the addition of chemical inducers, thus minimizing contamination risks. Multiple aspects of the molecular origin and biotechnological uses of its regulatory elements (pL/pR promoters and cI857 thermolabile repressor) derived from bacteriophage λ provide knowledge to improve the bioprocesses using this system. Here, we discuss the main aspects of the potential use of the λpL/pR-cI857 thermoinducible system for RP production in E. coli, focusing on the approaches of investigations that have contributed to the advancement of this expression system. Metabolic and physiological changes that occur in the host cells caused by heat stress and RP overproduction are also described. Therefore, the current scenario and the future applications of systems that use heat to induce RP production are discussed to understand the relationship between the activation of the bacterial heat shock response, RP accumulation and its possible aggregation to form inclusion bodies. This review highlights the use of Escherichia coli thermoinducible system for recombinant protein production, and the relationship between the heat shock response, the concomitant expression of chaperones and formation of inclusion bodies.