A Two-Layer Gene Circuit for Decoupling Cell Growth from Metabolite Production

• Published in: Cell systems Vol. 3; no. 2; pp. 133 - 143
• Main Authors: Lo, Tat-Ming, Chng, Si Hui, Teo, Wei Suong, Cho, Han-Saem, Chang, Matthew Wook
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 24.08.2016
• Subjects: autonomous regulation; Escherichia coli; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Gene Regulatory Networks; genetic controllers; genetic sensors; Glucose; Growth; Metabolic Engineering; Metabolic Networks and Pathways; synthetic biology; genetic sensors; synthetic biology; autonomous regulation; genetic controllers
• ISSN: 2405-4712; 2405-4720
• DOI: 10.1016/j.cels.2016.07.012

We present a synthetic gene circuit for decoupling cell growth from metabolite production through autonomous regulation of enzymatic pathways by integrated modules that sense nutrient and substrate. The two-layer circuit allows Escherichia coli to selectively utilize target substrates in a mixed pool; channel metabolic resources to growth by delaying enzymatic conversion until nutrient depletion; and activate, terminate, and re-activate conversion upon substrate availability. We developed two versions of controller, both of which have glucose nutrient sensors but differ in their substrate-sensing modules. One controller is specific for hydroxycinnamic acid and the other for oleic acid. Our hydroxycinnamic acid controller lowered metabolic stress 2-fold and increased the growth rate 2-fold and productivity 5-fold, whereas our oleic acid controller lowered metabolic stress 2-fold and increased the growth rate 1.3-fold and productivity 2.4-fold. These results demonstrate the potential for engineering strategies that decouple growth and production to make bio-based production more economical and sustainable. [Display omitted] •Novel modular genetic sensor controllers decouple cell growth and production•The controllers interconnect substrate- and nutrient-sensing genetic modules•The controllers eliminate the need for inducers and separation of substrate mixtures•The controllers lower metabolic stress and increase growth and productivity Lo et al. present an engineering biology strategy of autonomously decoupling growth and production through modular genetic sensor controllers to improve economics and sustainability in microbial cell factories. The genetic controllers eliminate the need for costly inducers and the separation of substrate mixtures significantly alleviate metabolic stress, and improve host growth and production rates.