P130: Production of precursors of isooctane in E. coli by type I polyketide synthase

Engineered biosynthesis and synthetic biology has opened the way to develop practical platforms to produce biofuels.  One major route is to reengineer an industrially tractable organism that can produce biofuels, such as E. coli, to utilize electricity and CO₂ as its energy and carbon sources, respectively.  We propose to engineer E. coli to serve as an “electrofuels chassis” for producing a central metabolic building block (acetyl-CoA) from electricity, H₂O, and CO₂.   Then, a novel metabolic pathway is inserted into this chassis that will convert acetyl-CoA to isooctane precursors via a polyketide biosynthetic pathway.  Although polyketide synthases vary greatly in size and structure, they share a mechanism of biosynthesis - a programmed, stepwise process that leads to the generation of molecules of unique and predictable structure.  In nature, the polyketide synthase systems are composed of large multifunctional proteins that are responsible for the production of thousands of bioactive compounds.  Our proposed chimeric PKS proteins will catalyze the condensation of methylmalonyl-CoA with either isobutyryl-CoA or pivaloyl-CoA to form isooctanoate, a precursor to isooctane. None of these building blocks are typical E. coli metabolites, so we have devised a number of engineered pathways to produce these molecules in this host.