Altering 15-Lipoxygenases to 18-Lipoxygenases and Their Application to the Production of 5,18-Dihydroxyeicosapentaenoic Acids

Abstract

Resolvin E2 (RvE2), 5S,18R-dihydroxyeicosapentaenoic acid (5S,18R-DiHEPE), and 18S-RvE2 (5S,18S-DiHEPE) are specialized pro-resolving mediators that function in the resolution of inflammation. These SPMs have been produced in trace amounts from eicosapentaenoic acid (EPA) using acetylated cyclooxygenase-2 or cytochrome P450 and 5-lipoxygenase (5-LOX) via 18R- and 18S-hydroxyeicosapentaenoic acid (18R- and 18S-HEPE) intermediates. In this study, we engineered 15R-LOX from Sorangium cellulosum and 15S-LOX from Archangium violaceum into 18R-LOX (L423W/L424M/L568M variant of 15R-LOX) and 18S-LOX (L429W/L430M/L575M variant of 15S-LOX), respectively, via structure-guided enzyme engineering. The engineered 18R-LOX converted EPA into 72.5% 18R-HEPE and 27.5% 15R-HEPE, while the engineered 18S-LOX formed 81.8% 18S-HEPE and 18.2% 15S-HEPE. Escherichia coli expressing the engineered 18R- or 18S-LOX converted 4.0 or 3.0 mM EPA into 2.0 mM (641 mg/L) 18R-HEPE or 1.8 mM (577 mg/L) 18S-HEPE in 20 min, respectively, achieving concentrations that were > 10⁵-fold higher than those reported previously. Furthermore, 5S-LOX from Danio rerio (zebrafish) converted a concentration of 0.5 mM of the prepared 18R- or 18S-HEPE into 0.24 mM (81 mg/L) RvE2 or 0.22 mM (74 mg/L) 18S-RvE2 in 30 min, respectively. To the best of our knowledge, this represents the first identification of 18-LOXs and first qualitative production of RvE2 and 18S-RvE2.