Characterization of Both Polyunsaturated Fatty Acid Biosynthetic Pathways in <i>Schizochytrium</i> sp.

Lippmeier, J. Casey; Crawford, Kristine S.; Owen, Carole; Rivas, Angie A.; Metz, James G.; Apt, Kirk E.

doi:10.1007/s11745-009-3311-9

Cited by 129 publications

(83 citation statements)

References 25 publications

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“…ATCC 20888 failed to reveal the expected number and types of elongase and desaturase, whereas PKS-homologous sequences were well represented. In contrast, a recent study using radiolabeled precursor fatty acids revealed that this strain had several elongase and desaturase activities associated with the elongation/ desaturation pathway, but the pathway was incomplete for the synthesis of PUFAs from C16 or C18 fatty acids 21 . Although it is unclear why Δ5-elongase or Δ4-desaturase was not amplified from the genus Aurantiochytrium in this study, it could be due to a mismatch of the degenerated primers used or low sequence homology of these genes in Aurantiochytrium.…”

Section: Discussionmentioning

confidence: 63%

Detection of Genes Involved in Fatty Acid Elongation and Desaturation in Thraustochytrid Marine Eukaryotes

et al. 2011

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Section: Discussionmentioning

confidence: 63%

Detection of Genes Involved in Fatty Acid Elongation and Desaturation in Thraustochytrid Marine Eukaryotes

et al. 2011

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“…which is particularly interesting as it also has two alternative pathways for DHA synthesis and contains a polyketide pathway not requiring aerobic desaturases (33,34). However, as expected, the phylogenetic analysis showed that the S. canaliculatus Δ4 Fad was more closely related to other vertebrate Δ6 and Δ5 Fads than the algal and protozoan Δ4 desaturases (35).…”

Section: Discussionmentioning

confidence: 64%

Vertebrate fatty acyl desaturase with Δ4 activity

Monroig

Zhang

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

239

228

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Biosynthesis of the highly biologically active long-chain polyunsaturated fatty acids, arachidonic (ARA), eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids, in vertebrates requires the introduction of up to three double bonds catalyzed by fatty acyl desaturases (Fad). Synthesis of ARA is achieved by Δ6 desaturation of 18∶2n − 6 to produce 18∶3n − 6 that is elongated to 20∶3n − 6 followed by Δ5 desaturation. Synthesis of EPA from 18∶3n − 3 requires the same enzymes and pathway as for ARA, but DHA synthesis reportedly requires two further elongations, a second Δ6 desaturation and a peroxisomal chain shortening step. This paper describes cDNAs, fad1 and fad2, isolated from the herbivorous, marine teleost fish (Siganus canaliculatus) with high similarity to mammalian Fad proteins. Functional characterization of the cDNAs by heterologous expression in the yeast Saccharomyces cerevisiae showed that Fad1 was a bifunctional Δ6∕Δ5 Fad. Previously, functional dual specificity in vertebrates had been demonstrated for a zebrafish Danio rerio Fad and baboon Fad, so the present report suggests bifunctionality may be more widespread in vertebrates. However, Fad2 conferred on the yeast the ability to convert 22∶5n − 3 to DHA indicating that this S. canaliculatus gene encoded an enzyme having Δ4 Fad activity. This is a unique report of a Fad with Δ4 activity in any vertebrate species and indicates that there are two possible mechanisms for DHA biosynthesis, a direct route involving elongation of EPA to 22∶5n − 3 followed by Δ4 desaturation, as well as the more complicated pathway as described above.Δ4 desaturase | bifunctional Δ6/Δ5 desaturase | polyunsaturated fatty acid biosynthesis | Siganus canaliculatus | teleost

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“…Primary production of in Schizochytrium is via a PUFA synthase (Metz et al, 2001), a series of 3 genes similar to those found in LC-PUFAproducing marine bacteria (Yazawa, 1996;Morita et al, 2000). In addition, a series of aerobic PUFA desaturase and elongase genes are also present in Schizochytrium (Lippmeier et al, 2009). …”

Section: 23microalgaementioning

confidence: 90%

“…are particularly interesting as they appear to have two alternative pathways for n-3 LC-PUFA biosynthesis (Lippmeier et al, 2009). Primary production of in Schizochytrium is via a PUFA synthase (Metz et al, 2001), a series of 3 genes similar to those found in LC-PUFAproducing marine bacteria (Yazawa, 1996;Morita et al, 2000).…”

Section: 23microalgaementioning

confidence: 99%

Omega-3 long-chain polyunsaturated fatty acids and aquaculture in perspective

2015

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Abbreviations: ARA, arachidonic acid (20:4n-6); CVD, cardiovascular disease; DHA, docosahexaenoic acid (22:6n-3); DPA, docosapentaenoic acid (22:5n-3); EFA, essential fatty acid; Elovl, fatty acid elongase; EPA, eicosapentaenoic acid (20:5n-3); Fads, fatty acyl desaturase; FM, fishmeal; FO, fish oil; LC-PUFA, long-chain polyunsaturated fatty acids (≥ C20 ≥ 3 double bonds); LOA, linoleic acid (18:2n-6); LNA, linolenic acid (18:3n-3); PUFA, polyunsaturated fatty acid; TAG, triacylglycerol; VO, vegetable oil. ABSTRACTIn the 40 years since the essentiality of polyunsaturated fatty acids (PUFA) in fish was first established by determining quantitative requirements for 18:3n-3 and 18:2n-6 in rainbow trout, essential fatty acid (EFA) research has gone through distinct phases. For 20 years the focus was primarily on determining qualitative and quantitative EFA requirements of fish species. Nutritional and biochemical studies showed major differences between fish species based on whether C 18 PUFA or long-chain (LC)-PUFA were required to satisfy requirements. In contrast, in the last 20 years, research emphasis shifted to determining "optimal" levels of EFA to support growth of fish fed diets with increased lipid content and where growth expectations were much higher. This required greater knowledge of the roles and functions of EFA in metabolism and physiology, and how these impacted on fish health and disease. Requirement studies were more focused on early life stages, in particular larval marine fish, defining not only levels, but also balances between different EFA. Finally, a major driver in the last 10-15 years has been the unavoidable replacement of fish oil and fishmeal in feeds and the impacts that this can have on n-3 LC-PUFA contents of diets and farmed fish, and the human consumer. Thus, dietary n-3 in fish feeds can be defined by three levels.Firstly, the minimum level required to satisfy EFA requirements and thus prevent nutritional pathologies. This level is relatively small and easy to supply even with today's current high demand for fish oil. The second level is that required to sustain maximum growth and optimum health in fish being fed modern high-energy diets. The balance between different PUFA and LC-PUFA is important and defining them is more challenging, and so ideal levels and balances are still not well understood, particularly in relation to fish health. The third level is currently driving much research; how can we supply sufficient n-3 LC-PUFA to maintain the nutritional quality of farmed fish at the same level as 20 years ago, and similar or better than in wild fish? This level far exceeds the biological requirements of the fish itself and to satisfy it we require entirely new sources of n-3 LC-PUFA. We cannot rely on the finite and limited marine resources that we can sustainably harvest or 3 efficiently recycle. We need to produce n-3 LC-PUFA de novo and all possible options should be considered.Keywords: Fish oil; essential fatty acids; nutrition; health; metabolism; sustainability 4 Highl...

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Characterization of Both Polyunsaturated Fatty Acid Biosynthetic Pathways in Schizochytrium sp.

Cited by 129 publications

References 25 publications

Detection of Genes Involved in Fatty Acid Elongation and Desaturation in Thraustochytrid Marine Eukaryotes

Detection of Genes Involved in Fatty Acid Elongation and Desaturation in Thraustochytrid Marine Eukaryotes

Vertebrate fatty acyl desaturase with Δ4 activity

Omega-3 long-chain polyunsaturated fatty acids and aquaculture in perspective

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