Linkage of Marine Bacterial Polyunsaturated Fatty Acid and Long-Chain Hydrocarbon Biosynthesis.

Various marine gamma-proteobacteria produce omega-3 polyunsaturated fatty acids, such as eicosapentaenoic acid (20:5, EPA) and docosahexaenoic acid (22:6, DHA), which are incorporated into membrane phospholipids. Five genes, designated , encode the polyketide/fatty acid synthase necessary for production of these long-chain fatty acids. In addition to biosynthesis of EPA and DHA, the "Pfa synthase" is also involved with production of a long-chain polyunsaturated hydrocarbon product (31:9, PUHC) in conjunction with the hydrocarbon biosynthesis pathway. In this work, we demonstrate that OleA mediates the linkage between these two pathways . Co-expression of along with from in yielded the expected product, a 31:8 ketone along with a dramatic ∼10-fold reduction in EPA content. The decrease in EPA content was independent of 31:8 ketone production as co-expression of an OleA active site mutant also led to identical decreases in EPA content. We also demonstrate that a gene linked with either and/or operons in diverse bacterial lineages, herein designated , plays a role in maintaining optimal production of Pfa synthase derived products in and species.