Design of Dynamic Pathways

Microbial production of chemicals has provided an attractive alternative to chemical synthesis. A key to make this technology economically viable is to improve titers, productivities, and strain robustness, all of which are often limited by metabolic imbalances. To overcome this problem, dynamic regulation is desired to adjust gene expression and metabolite concentrations to desirable levels, thus reducing cellular stress and avoiding waste of carbon and energy.This chapter will focus on current technologies used to design and build dynamic regulatory systems. This chapter starts from the basics of dynamic regulation to provide a general introduction and rationale of the technologies being used. Next, we will discuss current progress in experimental design of dynamic pathways using various design principles at transcriptional, translational, and posttranslational levels. Besides the experimental approaches, recent progress on mathematical models will also be covered. In addition, we will summarize available tools for the construction and fine-tuning of dynamic pathways, and available models for simulation, with the aim to provide a general guide to design dynamic pathways. Finally, we will discuss future directions in the field of dynamic regulation. With the development of more sophisticated synthetic biology tools and deeper understanding of metabolic dynamics, we expect dynamic regulated pathways to become mainstream in future metabolic engineering, improving productivities, yields, and robustness of the engineered microbial cell factories.