title: Novel, versatile, and tightly regulated expression system for Escherichia coli strains.
abstract: A novel tightly regulated gene expression system was developed for Escherichia coli by applying the regulatory elements of the Pseudomonas putida F1 cym and cmt operons to control target gene expression at the transcriptional level by using p-isopropylbenzoate (cumate) as an inducer. This novel expression system, referred to as the cumate gene switch, includes a specific expression vector, pNEW, that contains a partial T5 phage promoter combined with the Pseudomonas-based synthetic operator and the cymR repressor protein-encoding gene designed to express constitutively in the host strain. The induction of transcription relies on the addition of the exogenous inducer (cumate), which is nontoxic to the culture, water soluble, and inexpensive. The characteristics and potential of the expression system were determined. Using flow cytometry and fed-batch fermentations, we have shown that, with the newly developed cumate-regulated system, (i) higher recombinant product yields can be obtained than with the pET (isopropyl-beta-D-thiogalactopyranoside [IPTG])-induced expression system, (ii) expression is tightly regulated, (iii) addition of cumate quickly results in a fully induced and homogenous protein-expressing population in contrast to the bimodal expression profile of an IPTG-induced population, (iv) expression can be modulated by varying the cumate concentration, and (v) the cumate-induced population remains induced and fully expressing even at 8 h following induction, resulting in high yields of the target protein Furthermore, the cumate gene switch described in this article is applicable to a wide range of E. coli strains.
authors.affiliation: Microbial and Enzymatic Technology Group, Bioprocess Centre, Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Ave., Montreal, Quebec H4P 2R2, Canada.
authors.forename: Young J
authors.initials: YJ
authors.lastname: Choi
authors.forename: Lyne
authors.initials: L
authors.lastname: Morel
authors.forename: Teffanie
authors.initials: T
authors.lastname: Le François
authors.forename: Denis
authors.initials: D
authors.lastname: Bourque
authors.forename: Lucie
authors.initials: L
authors.lastname: Bourget
authors.forename: Denis
authors.initials: D
authors.lastname: Groleau
authors.forename: Bernard
authors.initials: B
authors.lastname: Massie
authors.forename: Carlos B
authors.initials: CB
authors.lastname: Míguez
mesh_terms: D001565:Benzoates / Q000378:metabolism; D003001:Cloning, Molecular / Q000379:methods*; D004926:Escherichia coli / Q000235:genetics*; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005818:Genetic Engineering / Q000379:methods*; D005822:Genetic Vectors; D011549:Pseudomonas; D016958:Pseudomonas putida / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000235:genetics; D015533:Transcriptional Activation
chemical_list: D001565:Benzoates; D011994:Recombinant Proteins; C055607:cumic acid