FEMS Microbiology Reviews, fuab023, 45, 2021, 1–19 https://doi.org/10.1093/femsre/fuab023 Advance Access Publication Date: 12 April 2021 Review Article REVIEW ARTICLE Thermoinducible expression system for producing recombinant proteins in Escherichia coli: advances and insights Sara Restrepo-Pineda 1 ,N´ estor O. P´ erez 2 , Norma A. Valdez-Cruz 1 and Mauricio A. Trujillo-Rold´ an 1, * 1 Unidad de Bioprocesos, Departamento de Biolog´ ıa Molecular y Biotecnolog´ ıa, Instituto de Investigaciones Biom ´ edicas, Universidad Nacional Aut ´ onoma de M ´ exico, CP 04510, Ciudad de M ´ exico, M ´ exico and 2 Probiomed S.A. de C.V. Planta Tenancingo, Cruce de Carreteras Acatzingo-Zumpahuacan SN, 52400 Tenancingo, Estado de M´ exico, M ´ exico ∗ Corresponding author: Unidad de Bioprocesos, Instituto de Investigaciones Biom´ edicas, Universidad Nacional Aut ´ onoma de M ´ exico, CP 04510, Ciudad de M ´ exico, M ´ exico. Tel: +52-5556229192; E-mail: maurotru@gmail.com, maurotru@biomedicas.unam.mx One sentence summary: 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. Editor: Grzegorz Wegrzyn ABSTRACT Recombinant protein (RP) production from Escherichia coli has been extensively studied to fnd 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. Keywords: E. coli; thermoinducible expression system; recombinant proteins; heat shock response; chaperones; inclusion bodies INTRODUCTION Escherichia coli is one of the best characterized models for sci- entifc research and has become the workhorse for producing different recombinant proteins (RPs) for industrial and phar- maceutical purposes (Chen 2012; Baeshen et al. 2015; Sanchez- Garc´ ıa et al. 2016). The reasons for the widespread use of E. coli include the high product yields, fast growth in economic sub- strates, possibility of performing high cell density cultures, vari- ety of mutant host strains and cloning vectors, ease of biopro- cess scale-up, and extensive knowledge regarding its genetics and metabolism (Baneyx 1999; Casali 2003; Huang, Lin and Yang 2012; Rosano, Morales and Ceccarelli 2019). Despite the inabil- ity to post-translationally modify proteins, and the tendency to Received: 6 February 2021; Accepted: 9 April 2021 C  The Author(s) 2021. Published by Oxford University Press on behalf of FEMS. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com 1 Downloaded from https://academic.oup.com/femsre/article/45/6/fuab023/6223457 by guest on 27 December 2023