Exploiting dynamics and cell-to-cell variation in metabolic engineering

Trustees Of Boston University, Boston

Investigators

Abstract

Cells can be engineered to produce products ranging from fuels to pharmaceuticals. However, the pathways that produce these products often reduce cell yields and increase costs. Turning these pathways on and off in some pattern might simultaneously reduce the burden and increase production. Conceptually, this approach is similar to a work week and weekend. It is based on the idea that a combination of work and time off can result in higher overall productivity than sustained, constant effort. The research is complemented by educational and training opportunities for high school students and undergraduates. These students will be prepared to participate in a high-technology workforce. Gene expression is noisy, leading to variation between cells in the absence of genetic diversity. Cells exploit that variability to optimize resource use. This calls into question whether introducing dynamics and noise in expression of genes could be beneficial. This project focuses on efflux pumps that export the monoterpene pinene. Pumps export toxic substrates and improve biosynthetic yields, but overexpressing them burdens the cell. Diversifying pump levels may allow populations to exploit these benefits and costs. The project is organized around two objectives: (1) to quantify single-cell differences in efflux and the duration of variability, and (2) to compare pinene production in strains with dynamic versus static pump expression. Time lapse microscopy coupled with microfluidics and quantitative image processing will be used to characterize pump variability. Pinene yields between strains with different approaches to pump expression will also be measured. Stochastic mathematical modeling to predict the impact of pump expression dynamics will complement the experiments. Overall, this project will test whether it is possible to exploit cell-to-cell variation in metabolic engineering to enhance production. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.