title: Disrupted short chain specific β-oxidation and improved synthase expression increase synthesis of short chain fatty acids in Saccharomyces cerevisiae.
abstract: Biologically derived fatty acids have gained tremendous interest as an alternative to petroleum-derived fuels and chemical precursors. We previously demonstrated the synthesis of short chain fatty acids in Saccharomyces cerevisiae by introduction of the Homo sapiens fatty acid synthase (hFAS) with heterologous phosphopantetheine transferases and heterologous thioesterases. In this study, short chain fatty acid production was improved by combining a variety of novel enzyme and metabolic engineering strategies. The use of a H. sapiens-derived thioesterase and phosphopantetheine transferase were evaluated. In addition, strains were engineered to disrupt either the full β-oxidation (by deleting FAA2, PXA1, and POX1) or short chain-specific β-oxidation (by deleting FAA2, ANT1, and PEX11) pathways. Prohibiting full β-oxidation increased hexanoic and octanoic acid levels by 8- and 79-fold relative to the parent strain expressing hFAS. However, by targeting only short chain β-oxidation, hexanoic and octanoic acid levels increased further to 31- and 140-fold over the parent. In addition, an optimized hFAS gene increased hexanoic, octanoic, decanoic and total short chain fatty acid levels by 2.9-, 2.0-, 2.3-, and 2.2-fold, respectively, relative to the non-optimized counterpart. By combining these unique enzyme and metabolic engineering strategies, octanoic acid was increased more than 181-fold over the parent strain expressing hFAS.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Irvine, 92697-2575, California.
authors.forename: Christopher
authors.initials: C
authors.lastname: Leber
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Irvine, 92697-2575, California.
authors.forename: Jin Wook
authors.initials: JW
authors.lastname: Choi
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Irvine, 92697-2575, California.
authors.forename: Brian
authors.initials: B
authors.lastname: Polson
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Irvine, 92697-2575, California. ndasilva@uci.edu.
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Da Silva
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D017353:Gene Deletion; D006801:Humans; D060847:Metabolic Engineering / Q000379:methods*; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D010084:Oxidation-Reduction; D010170:Palmitoyl-CoA Hydrolase / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism; D019076:Transgenes
chemical_list: D001426:Bacterial Proteins; D005232:Fatty Acids, Volatile; C082662:phosphopantetheinyl transferase; D017855:Transferases (Other Substituted Phosphate Groups); D010170:Palmitoyl-CoA Hydrolase
keywords: Homo sapiens fatty acid synthase; Saccharomyces cerevisiae; biorenewable chemicals; short chain fatty acids; β-oxidation