Improved fatty acid production using acyl-ACP thioesterase I mutants in Escherichia coli

Abstract

Recently, microbial fatty acid-based chemicals such as biofuels, cosmetics, and pharmaceutical drugs have a high potential to replace the petroleum-based chemicals. Although many researches have focused on the production of fatty acid, little information such as unknown global network regulators, secretion pumps, and optimal enzymatic activity is available on metabolic pathways. Previously, the expression of acyl-ACP thioesterase in vivo and in vitro showed maximal production of free fatty acid and cell growth when it was expressed at the medium level. While engineering of Escherichia coli thioesterase I (TesA) for high activity has a potential, its activity should be carefully optimized to enhance the fatty acid production. In this study, we created TesA mutants to provide the optimal enzymatic activity. Mutations of amino acid residues involved in substrate interaction and loop switch showed increased production of fatty acid. This is the first work to construct TesA mutant with optimal activity for increasing fatty acid production. Given that E. coli harboring the TesA mutant produces higher fatty acid, optimizing activity or expression level of enzymes involved in fatty acid biosynthesis enables microbes to further increase the production of oleochemicals.