UC Berkeley

Fatty acid biosynthesis creates highly-reduced hydrocarbons dubbed nature's petroleum. The pathway is responsible for products mostly used to build the lipid-bilayer of cell membranes, but also are implicated in cell signaling, brain function, and energy storage. As a source of natural hydrocarbons, we sought to exploit fatty acid biosynthesis for microbial production of a number of molecules including butanol, higher chain fatty alcohols, fatty acid ethyl esters (biodiesel), wax esters and long chain diacids. We attempted to exploit the two main forms of fatty acid biosynthesis, type I and II, which are characterized by single polypeptides that encode multiple reactions or single polypeptides that encode single reactions, respectively. The different types of fatty acid biosynthesis are found in comparing prokaryotes and eukaryotes, thus we engineered both Escherichia coli and Saccharomyces cerevisiae. Our strategy for building and engineering a pathway is broadly applicable and consists of identifying requisite reactions and the enzymes that encode those reactions, expressing those enzymes in a single host, analyzing production levels of metabolites related to the pathway, generating a hypothesis that explains the system's behavior and re-perturbing it to test the hypothesis in an effort to more efficiently produce a molecule of interest. With this strategy we successfully constructed and engineered fatty acid pathways in E. coli and S. cerevisiae.