Reconfiguring\nthe Escherichia coli Electron Transport\nChain to Enhance <i>trans</i>-2-Decenoic\nAcid Production

<i>trans</i>-2-Decenoic acid is a pivotal α,β-medium-chain\nunsaturated fatty acid that serves as an essential intermediary in\nthe synthesis of 10-hydroxy-2-decenoic acid and various pharmaceutical\ncompounds. Biosynthesis yield of <i>trans</i>-2-decenoic\nacid by decanoic acid has significantly improved in recent years;\nhowever, the oxidative stress of Escherichia coli at high fatty acid concentrations restricts the conversion rate.\nHere, we introduced a combination of rational design and metabolic\nrewiring of the E. coli electron transport\nchain (ETC) to improve <i>trans</i>-2-decenoic acid production.\nOverexpressing ubiquinone (UbQ) biosynthesis genes enhanced the expression\nof ETC complex III: UbQ to reduce reactive oxygen species (ROS) accumulation.\nFurthermore, applying rotenone to inhibit ETC complex I improved the\nelectron transfer efficiency of complex II. The integration of Vitamin\nB<sub>5</sub> and B<sub>2</sub> into the fermentation process increased\nthe activities of fatty acyl-CoA synthetase (<sup><i>Ma</i></sup><i>MACS</i>) and fatty acyl-CoA dehydrogenase (<sup><i>Pp</i></sup><i>fadE</i>). Finally, the constructed E. coli BL21(DE3)(Δ<i>fadBJR</i>/pCDFDuet-1-<sup><i>Pp</i></sup><i>fadE</i>-<sup><i>Ma</i></sup><i>MACS</i>/pRSFDuet-1-sumo-<sup><i>Ct</i></sup><i>ydiI</i>-<i>ubiI</i>) strain exhibited\na 51.50% decrease in ROS and a 93.33% enhancement in <i>trans</i>-2-decenoic acid yield, reaching 1.45 g/L after 66 h, which is the\nhighest yield reported for flask fermentation. This study reports\nthe feasibility of rewiring the ETC regulation and energy metabolism\nto improve α,β-UCA biosynthesis efficiency.