Biotransformation of docosahexaenoic acid into 10R,17S-dihydroxydocosahexaenoic acid as protectin DX 10-epimer by serial reactions of arachidonate 8R- and 15S-lipoxygenases

Abstract

Protectins,10,, are belonged to specialized proresolving mediators (SPMs). Protectins are generated by polymorphonuclear leukocytes in humans and resolve in ammation and infection in trace amounts. However, the quantitative production of protectin Dx 10-epimer (10-epi PDX, 10R,17S-4Z,7Z,11E,13Z,15E,19Z-DiHDHA) has been not attempted to date. In this study, 10-epi PDX was quantitatively produced from docosahexaenoic acid (DHA) by serial wholecell biotransformation of Escherichia coli expressing arachidonate (ARA) 8R-lipoxygenase (8R-LOX) from the coral Plexaura homomalla and E. coli expressing ARA 15S-LOX from the bacterium Archangium violaceum. The optimal bioconversion conditions to produce 10R-hydroxydocosahexaenoic acid (10R-HDHA) and 10-epi PDX were pH 8.0, 30°C, 2.0 mM DHA, and 4.0 g/L cells; and pH 8.5, 20°C, 1.4 mM 10R-HDHA, and 1.0 g/L cells, respectively. Under these optimized conditions, 2.0 mM (657 mg/L) DHA was converted into 1.2 mM (433 mg/L) 10-epi PDX via 1.4 mM (482 mg/L) 10R-HDHA by the serial whole-cell biotransformation within 90 min, with a molar conversion of 60% and volumetric productivity of 0.8 mM/h (288 mg/L/h). To the best of our knowledge, this is the rst quantitative production of 10-epi PDX. Our results contribute to the e cient biocatalytic synthesis of SPMs.