Dataset Information

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.

SUBMITTER: Allemann MN

PROVIDER: S-EPMC6463001 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Publications

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

Allemann Marco N MN Shulse Christine N CN Allen Eric E EE

Frontiers in microbiology 20190403

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 <i>pfaABCDE</i>, encode the polyketide/fatty acid synthase necessary for production of these long-chain fatty acids. In addition to <i>de novo</i> biosynthesis of EPA and DHA, the "Pfa synthase" is also involved with production of a long-chain polyunsaturated hydr ...[more]

PMID: 31024488

Similar Datasets

Project description:Docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (ARA, 20:4n-6) are the major long chain polyunsaturated fatty acids (LCPUFA) of the central nervous system. We examined the alterations in transcriptional profiles in neonate baboon cerebral cortex brain tissue using high-density Affymetrix oligonucleotide arrays ("U133 plus 2.0"). Twelve neonates were divided into 3 groups: Control (C, no DHA-ARA); 1× LCPUFA (L, 0.33%DHA-0.67%ARA); 3× LCPUFA (L3, 1.00%DHA-0.67%ARA). Significance analysis (P < 0.05) of a total of >54,000 probe sets (ps) identified changes in expression levels of 1108 ps, representing 2.05% of the total ps on the oligoarray, with most ps showing <2-fold change. Comparing L and C, 534 ps were upregulated with supplementation, and 574 ps were downregulated. For the L3/C comparisons, 666 ps were upregulated and 442 ps were downregulated. Characterization of differentially regulated genes by gene ontology assign them to diverse biological functions, notably lipid metabolism, ion channel and transport, G-protein and signal transduction, development, visual perception, membrane function, apoptosis, cytoskeleton, peptidases, cell cycle, stress response, kinases and phosphatases, transcription regulation, receptors, and ubiquitin, with about 400 transcripts having no defined function. Of differentially expressed genes involved in lipid metabolism, PLA2G6, a phospholipase recently associated with infantile neuroaxonal dystrophy, was downregulated in both LCPUFA groups. ELOVL5, a PUFA elongase, was the only enzyme in the LCPUFA biosynthetic pathway that was differentially expressed. Mitochondrial fatty acid carrier, CPT2, was among several genes associated with mitochondrial fatty acid oxidation to be downregulated, while the mitochondrial proton carrier, UCP2, was upregulated. PUFA-regulated receptor, Retinoic acid receptor alpha (RARA) was repressed in both groups, while HNF4A, a PUFA regulated factor, was downregulated in L3/C. Genes involved in neural development, TIMM8A, NRG1, SEMA3D and NUMB, were upregulated while HES1 and SIM1 showed decreased expression. LUM, EML2, TIMP3 and TTC8 which have roles in visual perception were upregulated and TIA1, a silencer of COX2 gene translation is upregulated in L3/C. Ingenuity network analysis identified a top network associated with nervous system development and function with EGFR as the outstanding interaction partner. In this network EGFR interacts with genes involved in neural or visual perception, TIMP3, NRG1, ADAM17, EDG7 and FGF7. Quantitative real time-PCR analysis on selected genes confirmed the array results. The L and L3 groups have DHA and ARA content within the ranges observed in human and baboon breastmilk, and thus these data indicate that LCPUFA concentrations within the normal range of human breastmilk induce global changes in gene expression across numerous functions including transcripts involved in neural development, visual perception, etc. Keywords: dietary dose response

Project description:BackgroundΔ6-Desaturase (Fads2) is widely regarded as rate-limiting in the conversion of dietary α-linolenic acid (18:3n-3; ALA) to the long-chain omega-3 polyunsaturated fatty acid docosahexaenoic acid (22:6n-3; DHA). However, increasing dietary ALA or the direct Fads2 product, stearidonic acid (18:4n-3; SDA), increases tissue levels of eicosapentaenoic acid (20:5n-3; EPA) and docosapentaenoic acid (22:5n-3; DPA), but not DHA. These observations suggest that one or more control points must exist beyond ALA metabolism by Fads2. One possible control point is a second reaction involving Fads2 itself, since this enzyme catalyses desaturation of 24:5n-3 to 24:6n-3, as well as ALA to SDA. However, metabolism of EPA and DPA both require elongation reactions. This study examined the activities of two elongase enzymes as well as the second reaction of Fads2 in order to concentrate on the metabolism of EPA to DHA.Methodology/principal findingsThe substrate selectivities, competitive substrate interactions and dose response curves of the rat elongases, Elovl2 and Elovl5 were determined after expression of the enzymes in yeast. The competitive substrate interactions for rat Fads2 were also examined. Rat Elovl2 was active with C(20) and C(22) polyunsaturated fatty acids and this single enzyme catalysed the sequential elongation reactions of EPA→DPA→24:5n-3. The second reaction DPA→24:5n-3 appeared to be saturated at substrate concentrations not saturating for the first reaction EPA→DPA. ALA dose-dependently inhibited Fads2 conversion of 24:5n-3 to 24:6n-3.ConclusionsThe competition between ALA and 24:5n-3 for Fads2 may explain the decrease in DHA levels observed after certain intakes of dietary ALA have been exceeded. In addition, the apparent saturation of the second Elovl2 reaction, DPA→24:5n-3, provides further explanations for the accumulation of DPA when ALA, SDA or EPA is provided in the diet. This study suggests that Elovl2 will be critical in understanding if DHA synthesis can be increased by dietary means.

Project description:Docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (ARA, 20:4n-6) are the major long chain polyunsaturated fatty acids (LCPUFA) of the central nervous system. We examined the alterations in transcriptional profiles in neonate baboon cerebral cortex brain tissue using high-density Affymetrix oligonucleotide arrays ("U133 plus 2.0"). Twelve neonates were divided into 3 groups: Control (C, no DHA-ARA); 1Ã LCPUFA (L, 0.33%DHA-0.67%ARA); 3Ã LCPUFA (L3, 1.00%DHA-0.67%ARA). Significance analysis (P < 0.05) of a total of >54,000 probe sets (ps) identified changes in expression levels of 1108 ps, representing 2.05% of the total ps on the oligoarray, with most ps showing <2-fold change. Comparing L and C, 534 ps were upregulated with supplementation, and 574 ps were downregulated. For the L3/C comparisons, 666 ps were upregulated and 442 ps were downregulated. Characterization of differentially regulated genes by gene ontology assign them to diverse biological functions, notably lipid metabolism, ion channel and transport, G-protein and signal transduction, development, visual perception, membrane function, apoptosis, cytoskeleton, peptidases, cell cycle, stress response, kinases and phosphatases, transcription regulation, receptors, and ubiquitin, with about 400 transcripts having no defined function. Of differentially expressed genes involved in lipid metabolism, PLA2G6, a phospholipase recently associated with infantile neuroaxonal dystrophy, was downregulated in both LCPUFA groups. ELOVL5, a PUFA elongase, was the only enzyme in the LCPUFA biosynthetic pathway that was differentially expressed. Mitochondrial fatty acid carrier, CPT2, was among several genes associated with mitochondrial fatty acid oxidation to be downregulated, while the mitochondrial proton carrier, UCP2, was upregulated. PUFA-regulated receptor, Retinoic acid receptor alpha (RARA) was repressed in both groups, while HNF4A, a PUFA regulated factor, was downregulated in L3/C. Genes involved in neural development, TIMM8A, NRG1, SEMA3D and NUMB, were upregulated while HES1 and SIM1 showed decreased expression. LUM, EML2, TIMP3 and TTC8 which have roles in visual perception were upregulated and TIA1, a silencer of COX2 gene translation is upregulated in L3/C. Ingenuity network analysis identified a top network associated with nervous system development and function with EGFR as the outstanding interaction partner. In this network EGFR interacts with genes involved in neural or visual perception, TIMP3, NRG1, ADAM17, EDG7 and FGF7. Quantitative real time-PCR analysis on selected genes confirmed the array results. The L and L3 groups have DHA and ARA content within the ranges observed in human and baboon breastmilk, and thus these data indicate that LCPUFA concentrations within the normal range of human breastmilk induce global changes in gene expression across numerous functions including transcripts involved in neural development, visual perception, etc. Experiment Overall Design: Twelve baboon neonates born spontaneously around 182 days gestation were randomized into 3 groups (n=4 per group). They were fed for 12 weeks on one of three formulas: C: Control (no DHA-ARA); L: 1Ã LCPUFA (0.33%DHA-0.67%ARA); L3: 3Ã LCPUFA (1.00%DHA-0.67%ARA).

Dataset Information

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

Publications

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

Similar Datasets

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