AUTHOR=Allemann Marco N. , Shulse Christine N. , Allen Eric E. 

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

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.00702

DOI=10.3389/fmicb.2019.00702

ISSN=1664-302X

ABSTRACT=<p>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 <italic>pfaABCDE</italic>, encode the polyketide/fatty acid synthase necessary for production of these long-chain fatty acids. In addition to <italic>de novo</italic> 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 <italic>oleABCD</italic> hydrocarbon biosynthesis pathway. In this work, we demonstrate that OleA mediates the linkage between these two pathways <italic>in vivo</italic>. Co-expression of <italic>pfaA-E</italic> along with <italic>oleA</italic> from <italic>Shewanella pealeana</italic> in <italic>Escherichia coli</italic> 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 <italic>pfa</italic> and/or <italic>ole</italic> operons in diverse bacterial lineages, herein designated <italic>pfaT</italic>, plays a role in maintaining optimal production of Pfa synthase derived products in <italic>Photobacterium</italic> and <italic>Shewanella</italic> species.</p>