(725e) A Semi-Synthetic Regulatory Infrastructure Can Remodel Yeast Global Phenotypic State for Rapid Growth on Non-Native Nutrients of Choice

The yeast Saccharomyces cerevisiae is a popular platform organism for biosynthesis of biofuels and biochemicals. However, the range of carbon sources it can metabolize is very limited, which prevents valorization of many cheap and abundant substrates by this species. In the last several decades, significant effort has been expended on engineering yeast to metabolize non-native nutrients/substrates like xylose, arabinose, cellobiose, cellulose, etc. However, even after extensive engineering efforts, including a variety of rational and combinatorial methods, success has not been as significant as hoped and growth rates of strains on non-native nutrients have not matched those on native nutrients like glucose or galactose. In this talk we will discuss our recent work (Endalur Gopinarayan & Nair 2018 Nature Communications) where we demonstrated that by rationally remodelling the phenotypic state of yeast for fast growth using a semi-synthetic global regulatory infrastructure (i.e., regulon) we can achieve rapid growth on xylose. We also elucidate that underlying reason for our favorable outcome is due to activation of growth responsive genes like cell cycle progression genes, cell wall biosynthesis, etc. and downregulation of stress and starvation responses that are generally activated when yeast is grown on non-native nutrients. We will also discuss how this regulon engineering paradigm can be extended to alternate non-native nutrients like arabinose to achieve rapid growth. We also highlight that such this strategy requires minimal metabolic engineering and can provide fast growth rates even without any long-term adaptive evolution. Although, we also demonstrate that this strategy is compatible with most current strain engineering strategies like metabolic de-bottlenecking and pathway refactoring. Thus, we posit that our approach of applying synthetic biological circuits with metabolic engineering can be synergistically beneficial for developing strains that can metabolize a spectrum of desirable substrates. As such, this work highlights how the current paradigm of overexpression and adaptive evolution may be limiting maximum achievable growth rates and that regulon engineering may be a novel path forward for rapid engineering to expand the usable substrate range for this yeast.