Engineering glucose metabolism of Escherichia coli under nitrogen starvation

Victor Chubukov; John James Desmarais; George Wang; Leanne Jade G Chan; Edward Ek Baidoo; Christopher J Petzold; Jay D Keasling; Aindrila Mukhopadhyay

doi:10.1038/npjsba.2016.35

Engineering glucose metabolism of Escherichia coli under nitrogen starvation

NPJ Syst Biol Appl. 2017 Jan 5:3:16035. doi: 10.1038/npjsba.2016.35. eCollection 2017.

Authors

Victor Chubukov^{1

2}, John James Desmarais^{1

2}, George Wang^{1

2}, Leanne Jade G Chan^{1

2}, Edward Ek Baidoo^{1

2}, Christopher J Petzold^{1

2}, Jay D Keasling^{1

2

3

4

5}, Aindrila Mukhopadhyay^{1

2}

Affiliations

¹ Joint BioEnergy Institute, Emeryville, CA, USA.
² Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
³ Department of Chemical & Biomolecular Engineering, University of California, Berkeley, CA, USA.
⁴ Department of Bioengineering, University of California, Berkeley, CA, USA.
⁵ Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark.

Abstract

A major aspect of microbial metabolic engineering is the development of chassis hosts that have favorable global metabolic phenotypes, and can be further engineered to produce a variety of compounds. In this work, we focus on the problem of decoupling growth and production in the model bacterium Escherichia coli, and in particular on the maintenance of active metabolism during nitrogen-limited stationary phase. We find that by overexpressing the enzyme PtsI, a component of the glucose uptake system that is inhibited by α-ketoglutarate during nitrogen limitation, we are able to achieve a fourfold increase in metabolic rates. Alternative systems were also tested: chimeric PtsI proteins hypothesized to be insensitive to α-ketoglutarate did not improve metabolic rates under the conditions tested, whereas systems based on the galactose permease GalP suffered from energy stress and extreme sensitivity to expression level. Overexpression of PtsI is likely to be a useful arrow in the metabolic engineer's quiver as productivity of engineered pathways becomes limited by central metabolic rates during stationary phase production processes.