Microbial Synthesis of Therapeutic Bile Acids

ABSTRACT This Phase STTR Phase I proposal aims to engineer a synthetic metabolic pathway in a microbial host to produce UDCA and related compounds. The proposed work has high intellectual merit for the following reasons: (i) UDCA biosynthesis does not occur in any organism whose cultivation can be scaled to meet global demand, (ii) UDCA requires a multi-organism biosynthetic pathway (animal cholic acids converted to UDCA by the gut microbiome) that will have to be reconstituted in a single cell, and (iii) the anticipated scale and complexity of this engineering effort (combining more than a dozen genes from four organisms) are on the edge of what is feasible. Technical hurdles involve the discovery of new enzymes that convert ergosterol to cholesterol (a process known to exist in brine shrimp), achieving proper localization and enzymatic activity for fifteen recombinant gene products in yeast, and balancing the expression levels of each gene to support high-titer production of UDCA in yeast. The combined Metselex/University of Minnesota team will overcome these hurdles using their platform for multi-gene pathway refactoring and high-throughput DNA assembly and analytical methods. Experience with these tools/approaches and success in engineering similar synthetic metabolic pathways qualifies this team conduct these studies and will enable them to accomplish their Phase I goals.PROJECT NARRATIVE Metselex has succeeded in producing safe and effective ursodeoxycholic acid (UDCA) derivatives for treating neurodegenerative disease. However, the supply-chain of UDCA is limited and is driven by either (i) the inhumane/illegal harvesting of bile acids from bears, or (ii) semi-synthesis from starting materials isolated from animal gall bladders. The research proposed here will give Metselex an economical and sustainable source for UDCA via a synthetic metabolic pathway in yeast. Metselex is developing new first-line drugs to combat neurodegenerative diseases. Acute and chronic neurodegenerative diseases are the leading causes of death and disability in the USA and world. The economic burden on society that results from treatment costs and lost productivity is substantial. Current estimates of the cost of care are $262B per year for chronic neurodegenerative patients and $66B for acute neurodegenerative patients in the US, growing to $1T by 2050. The research proposed here will enable the large-scale production of new UDCA-derived therapeutics for these diseases that will result in better patient outcomes. Success of Metselex’s drug development pipeline depends on an economical source of UDCA, which will be produced on this effort. Lastly, the tools and techniques developed to overcome technical hurdles in this project will be broadly useful in the design and construction of other synthetic metabolic pathways to support a bio-based chemical production industry.