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

Abstract

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

Bacterial Diversity of Breast Milk in Healthy Spanish Women: Evolution from Birth to Five Years Postpartum

“…The levels of DHA were influenced by lactation time as well ( Table 6 ), and by dietary factors as nuts ( r = 0.284, p = 0.014) and cereal ( r = 0.318, p = 0.006) intake, but no association between Proteobacteria and these dietary factors was detected. Thus, Proteobacteria could be other factor that influences the levels of DHA in breast milk, as it has been demonstrated that some groups of Proteobacteria can synthetize omega-3 polyunsaturated fatty acids such as EPA (eicosapentaenoic) and DHA [ 70 , 71 ]. The genus Staphylococcus was positively correlated with C18:2 (n-6) 9,12 t ( r = 0.309, p = 0.035) and C18:2 (n-6) 10 t , 12 ( r = 0.301, p = 0.040) isomers [ 72 ].…”

Global analysis of adenylate-forming enzymes reveals β-lactone biosynthesis pathway in pathogenic Nocardia

“…Our findings suggest microbes might also use β-lactones as intermediates since we detected a number of β-lactone synthetase hits in gene clusters known to make natural products without final βlactone moieties such as polyunsaturated fatty acids. Indeed, β-lactone synthetases in oleABCD gene clusters were recently linked to production of the final alkene moiety in the biosynthesis of a C31 polyunsaturated hydrocarbon product (43). Such cases, if more widespread, may have also escaped detection because most of the predicted gene clusters with β-lactone synthetases were not detected by tools like antiSMASH until recently (23), prohibiting the discovery of such biosynthetic pathways through genome mining approaches.…”

Global analysis of adenylate-forming enzymes reveals β-lactone biosynthesis pathway in pathogenicNocardia

“…Our findings suggest microbes might also use β-lactones as intermediates since we detected a number of β-lactone synthetase hits in gene clusters known to make natural products without final βlactone moieties such as polyunsaturated fatty acids. Indeed, β-lactone synthetases in oleABCD gene clusters were recently linked to production of the final alkene moiety in the biosynthesis of a C31 polyunsaturated hydrocarbon product (40). Such cases, if more widespread, may have also escaped detection because most of the predicted gene clusters with β-lactone synthetases were not detected by tools like antiSMASH (20) until recently, prohibiting the discovery of such biosynthetic pathways through genome mining approaches.…”