title: Tunable recombinant protein expression in E. coli: promoter systems and genetic constraints.
abstract: Tuning of transcription is a promising strategy to overcome challenges associated with a non-suitable expression rate like outgrowth of segregants, inclusion body formation, metabolic burden and inefficient translocation. By adjusting the expression rate-even on line-to purposeful levels higher product titres and more cost-efficient production processes can be achieved by enabling culture long-term stability and constant product quality. Some tunable systems are registered for patents or already commercially available. Within this contribution, we discuss the induction mechanisms of various Escherichia coli inherent promoter systems with respect to their tunability and review studies using these systems for expression tuning. According to the current level of knowledge, some promoter systems were successfully used for expression tuning, and in some cases, analytical evidence on single-cell level is still pending. However, only a few studies using tunable strains apply a suitable process control strategy. So far, expression tuning has only gathered little attention, but we anticipate that expression tuning harbours great potential for enabling and optimizing the production of a broad spectrum of products in E. coli.
authors.affiliation: Institute of Chemical Engineering, Research Area Biochemical Engineering, Vienna University of Technology, Vienna, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Marschall
authors.affiliation: Exputec GmbH, Vienna, Austria.
authors.forename: Patrick
authors.initials: P
authors.lastname: Sagmeister
authors.affiliation: Institute of Chemical Engineering, Research Area Biochemical Engineering, Vienna University of Technology, Vienna, Austria. christoph.herwig@tuwien.ac.at.|Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Vienna University of Technology, Gumpendorferstrasse 1a/166-4, A-1060, Vienna, Austria. christoph.herwig@tuwien.ac.at.
authors.forename: Christoph
authors.initials: C
authors.lastname: Herwig
mesh_terms: D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000235:genetics*; D015533:Transcriptional Activation
chemical_list: D011994:Recombinant Proteins
keywords: All-or-none induction; E. coli; Promoter; Transcription; Tunable