Reductive biotransformation pathways in recombinant microorganisms regularly shift cellular homeostasis and intracellular redox ratios, requiring the further expression of exogenous enzymes or cautious fine-tuning of fluxes and cofactor specificities for optimum productivity and growth. To minimize these challenges to the cell, we worked to develop a functional, third redox cofactor pool in Saccharomyces cerevisiae to be used for the production of renewable products. To develop this system, we engineered S. cerevisiae to overproduce the noncanonical redox cofactor nicotinamide mononucleotide, NMN+, at intracellular levels similar to the native cofactors, NAD(P)+, by screening novel pathways to produce NMN+ from smaller precursors. Then, as a proof-of-concept, we established an NMN(H)-dependent cycling system using an engineering glucose dehydrogenase and the oxidoreductase XenA to utilize the intracellular NMN(H) pool to drive the production of levodione, a flavor and fragrance precursor. We envision this system can be applied to supply orthogonal reducing power across diverse substrate classes in reductive biotransformation in S. cerevisiae.

Engineering Saccharomyces cerevisiae for the utilization of a nicotinamide mononucleotide-mediated biotransformation system

ACS Spring 2022

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