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Liu Y, Han X, Chen Z, Yan Y, Chen Z. Selectively superior production of docosahexaenoic acid in Schizochytrium sp. through engineering the fatty acid biosynthetic pathways. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:75. [PMID: 38831337 PMCID: PMC11145866 DOI: 10.1186/s13068-024-02524-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 05/23/2024] [Indexed: 06/05/2024]
Abstract
BACKGROUND Schizochytrium sp. is commercially used for production of docosahexaenoic acid (DHA). Schizochytrium sp. utilizes the polyketide synthase complex (PKS) and a single type I fatty acid synthase (FAS) to synthesize polyunsaturated fatty acids and saturated fatty acids, respectively. The acyl carrier protein (ACP) domains of FAS or PKS are used to load acyl groups during fatty acids biosynthesis. Phosphopantetheinyl transferase (PPTase) transfers the pantetheine moiety from Coenzyme A to the conserved serine residue of an inactive ACP domain to produce its active form. RESULTS In this study, in order to improve production and content of DHA, we decreased the expression of fas, strengthened the expression of the PKS pathway, and enhanced the supply of active ACP in Schizochytrium sp. ATCC20888. Weakening the expression of fas or disruption of orfA both led to growth defect and reduction of lipid yields in the resulting strains WFAS and DPKSA, indicating that both FAS and PKS were indispensable for growth and lipid accumulation. Although WFAS had a higher DHA content in total fatty acids than the wild-type strain (WT), its growth defect and low DHA yield hinders its use for DHA production. Overexpression of the orfAB, orfC, orfC-DH (truncated orfC), or ppt promoted DHA and lipid production, respectively. The yields and contents of DHA were further increased by combined overexpression of these genes. Highest values of DHA yield (7.2 g/L) and DHA content (40.6%) were achieved in a recombinant OPKSABC-PPT, ⁓56.5% and 15.3% higher than the WT values, respectively. CONCLUSIONS This study demonstrates that genetic engineering of the fatty acid biosynthetic pathways provides a new strategy to enhance DHA production in Schizochytrium.
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Affiliation(s)
- Yana Liu
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xiao Han
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Zongcheng Chen
- College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China
| | - Yihan Yan
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Zhi Chen
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
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Guo P, Dong L, Wang F, Chen L, Zhang W. Deciphering and engineering the polyunsaturated fatty acid synthase pathway from eukaryotic microorganisms. Front Bioeng Biotechnol 2022; 10:1052785. [DOI: 10.3389/fbioe.2022.1052785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 11/02/2022] [Indexed: 11/16/2022] Open
Abstract
Polyunsaturated fatty acids (PUFAs) are important nutrients that play important roles in human health. In eukaryotes, PUFAs can be de novo synthesized through two independent biosynthetic pathways: the desaturase/elongase pathway and the PUFA synthase pathway. Among them, PUFAs synthesized through the PUFA synthase pathway typically have few byproducts and require fewer reduction equivalents. In the past 2 decades, numerous studies have been carried out to identify, analyze and engineer PUFA synthases from eukaryotes. These studies showed both similarities and differences between the eukaryotic PUFA synthase pathways and those well studied in prokaryotes. For example, eukaryotic PUFA synthases contain the same domain types as those in prokaryotic PUFA synthases, but the number and arrangement of several domains are different; the basic functions of same-type domains are similar, but the properties and catalytic activities of these domains are somewhat different. To further utilize the PUFA synthase pathway in microbial cell factories and improve the productivity of PUFAs, many challenges still need to be addressed, such as incompletely elucidated PUFA synthesis mechanisms and the difficult genetic manipulation of eukaryotic hosts. In this review, we provide an updated introduction to the eukaryotic PUFA synthase pathway, summarize the functions of domains and propose the possible mechanisms of the PUFA synthesis process, and then provide future research directions to further elucidate and engineer the eukaryotic PUFA synthase pathway for the maximal benefits of humans.
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Shuib S, Nazir MYM, Ibrahim I, Song Y, Ratledge C, Hamid AA. Co-existence of type I fatty acid synthase and polyketide synthase metabolons in Aurantiochytrium SW1 and their implications for lipid biosynthesis. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159224. [PMID: 36007759 DOI: 10.1016/j.bbalip.2022.159224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 08/16/2022] [Accepted: 08/16/2022] [Indexed: 11/26/2022]
Abstract
The key enzymes of lipid biosynthesis in oleaginous filamentous fungi exist as metabolons. However, the existence of a similar organization in other groups of oleaginous microorganisms is still unknown. In this study, we confirmed the occurrence of two separate and distinct lipogenic metabolons in a thraustochytrid, Aurantiochytrium SW1. These involve the Type I Fatty Acid Synthase (FAS) pathway, consisting of six enzymes: fatty acid synthase, malic enzyme (ME), ATP: citrate lyase (ACL), acetyl-CoA carboxylase (ACC), malate dehydrogenase (MD) and pyruvate carboxylase (PC), and the Polyketide Synthase-like (PKS) pathway, consisting of PKS subunits a, b, c, glucose-6-phosphate dehydrogenase (G6PDH) 6-phosphogluconate dehydrogenase (6PGDH), ACL and ACC. This suggests that the NADPH requirement for the FAS pathway is primarily generated and channelled by ME whereas G6PDH and 6PGDH fulfil this role for the PKS pathway. Diminished biosynthesis of palmitic acid (16:0), docosahexaenoic acid (22:6 n-3, DHA) and docosapentaenoic acid (22:5 n-6, DPA) correlated with the dissociation of their respective metabolons thereby suggesting that regulation of the pathways is achieved through the formation and dissociation of the metabolons.
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Affiliation(s)
- Shuwahida Shuib
- Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia; Autoimmune Unit, Allergy and Immunology Research Centre, Institute for Medical Research (IMR), National Institute of Health (NIH) Malaysia, No. 1, Jalan Setia Murni U13/52, Bandar Setia Alam, 40170 Shah Alam, Selangor, Malaysia
| | - Mohamed Yusuf Mohamed Nazir
- Department of Food Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia; Innovation Centre for Confectionery Technology (MANIS), Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
| | - Izyanti Ibrahim
- Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
| | - Yuanda Song
- Colin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Sciences, Shandong University of Technology, 266 Xincun Rd., Zibo, Shandong, PR China
| | - Colin Ratledge
- Department of Biological Sciences, University of Hull, Kingston upon Hull HU6 7RX, United Kingdom
| | - Aidil Abdul Hamid
- Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia.
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Functional Analysis of an Acyltransferase-Like Domain from Polyunsaturated Fatty Acid Synthase in Thraustochytrium. Microorganisms 2021; 9:microorganisms9030626. [PMID: 33803061 PMCID: PMC8003026 DOI: 10.3390/microorganisms9030626] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/15/2021] [Accepted: 03/15/2021] [Indexed: 12/19/2022] Open
Abstract
Biosynthesis of very long chain polyunsaturated fatty acids (VLCPUFA) such as docosahexaenoic acid (DHA, 22:6-4,7,10,13,16,19) and docosapentaenoic acid (DPA, 22:5-4,7,10,13,16) in protist Thraustochytrium is catalyzed by a polyunsaturated fatty acids (PUFA) synthase comprising three large subunits, each with multiple catalytic domains. This study used complementation test, in vitro assays, and functional expression to characterize an acyltransferase (AT)-like domain in Subunit-B of a PUFA synthase from Thraustochytrium. Complementation test in Escherichia coli showed that the AT-like domain could not restore the growth phenotype of a temperature-sensitive mutant (∆fabDts) defective in malonyl-CoA:ACP transacylase activity. In vitro assays showed that the AT-like domain possessed thioesterase activity towards a few acyl-CoAs tested where docosahexaenoyl-CoA (DHA-CoA) was the preferred substrate. Expression of this domain in an E. coli mutant (∆fadD) defective in acyl-CoA synthetase activity resulted in the increased accumulation of free fatty acids. Site-directed mutagenesis showed that the substitution of two putative active site residues, serine at 96 (S96) and histidine at 220 (H220), in the AT-like domain significantly reduced its activity towards DHA-CoA and accumulation of free fatty acids in the ∆fadD mutant. These results indicate that the AT-like domain of the PUFA synthase does not function as a malonyl-CoA:ACP transacylase, rather it functions as a thioesterase. It might catalyze the last step of the VLCPUFA biosynthesis by releasing freshly synthesized VLCPUFAs attached to ACP domains of the PUFA synthase in Thraustochytrium.
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Du F, Wang YZ, Xu YS, Shi TQ, Liu WZ, Sun XM, Huang H. Biotechnological production of lipid and terpenoid from thraustochytrids. Biotechnol Adv 2021; 48:107725. [PMID: 33727145 DOI: 10.1016/j.biotechadv.2021.107725] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/15/2021] [Accepted: 02/25/2021] [Indexed: 12/21/2022]
Abstract
As fungus-like protists, thraustochytrids have been increasingly studied for their faster growth rates and high lipid content. In the 1990s, thraustochytrids were used as docosahexaenoic acid (DHA) producers for the first time. Thraustochytrids genera, such as Thraustochytrium, Schizochytrium, and Aurantiochytrium have been developed and patented as industrial strains for DHA production. The high DHA yield is attributed to its unique and efficient polyketide-like synthase (PKS) pathway. Moreover, thraustochytrids possess a completed mevalonate (MVA) pathway, so it can be used as host for terpenoid production. In order to improve strain performance, the metabolic engineering strategies have been applied to promote or disrupt intracellular metabolic pathways, such as genetic engineering and addition of chemical activators. However, it is difficult to realize industrialization only by improving strain performance. Various operation strategies were developed to enlarge the production quantities from the laboratory-scale, including two-stage cultivation strategies, scale-up technologies and bioreactor design. Moreover, an economical and effective downstream process is also an important consideration for the industrial application of thraustochytrids. Downstream costs accounts for 20-60% of the overall process costs, which represents an attractive target for increasing the cost-competitiveness of thraustochytrids, including how to improve the efficiency of lipid extraction and the further application of biomass residues. This review aims to overview the whole lipid biotechnology of thraustochytrids to provide the background information for researchers.
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Affiliation(s)
- Fei Du
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2 Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - Yu-Zhou Wang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2 Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - Ying-Shuang Xu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2 Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - Tian-Qiong Shi
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2 Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - Wen-Zheng Liu
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2 Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - Xiao-Man Sun
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2 Xuelin Road, Qixia District, Nanjing, People's Republic of China.
| | - He Huang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2 Xuelin Road, Qixia District, Nanjing, People's Republic of China; College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing, People's Republic of China
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Xie X, Sun K, Meesapyodsuk D, Miao Y, Qiu X. Distinct functions of two FabA-like dehydratase domains of polyunsaturated fatty acid synthase in the biosynthesis of very long-chain polyunsaturated fatty acids. Environ Microbiol 2020; 22:3772-3783. [PMID: 32618113 DOI: 10.1111/1462-2920.15149] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 06/06/2020] [Accepted: 06/29/2020] [Indexed: 11/29/2022]
Abstract
Thraustochytrium is a unicellular marine protist for the commercial production of very long-chain polyunsaturated fatty acids (VLCPUFAs). Biosynthesis of these VLCPUFAs in the protist is catalysed by a PUFA synthase comprising three subunits, each with multiple catalytic domains. Among these domains, two tandem FabA-like dehydratase domains (DH1 and DH2) in subunit-C together are responsible for introducing double bonds in VLCPUFAs. Domain swapping analysis in yeast showed that the defective phenotype of a Scfas1 mutant could be complemented by expressing an engineered ScFAS1 gene in which the DH domain was replaced by a single DH1 or mutated DH2 of the two. Heterologous expression of the PUFA synthase in E. coli showed that the mutation of DH1 of the two or deletion of DH1 or substitution of DH1 with DH2 resulted in the complete loss of activity in the biosynthesis of VLCPUFAs. Mutation of DH2 of the two or deletion of the DH2 domain produced a small amount of DPA, but not docosahexaenoic acid (DHA). These results indicate that each of the two FabA-like domains of the PUFA synthase possesses distinct function. DH1 domain is essential for the biosynthesis of VLCPUFAs, but DH2 domain is required for the biosynthesis of DHA.
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Affiliation(s)
- Xi Xie
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5A8, Canada.,College of Light Industry and Food, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China
| | - Kaiwen Sun
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5A8, Canada
| | - Dauenpen Meesapyodsuk
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5A8, Canada.,National Research Council of Canada, Saskatoon, Saskatchewan, S7N 0W9, Canada
| | - Yu Miao
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5A8, Canada
| | - Xiao Qiu
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5A8, Canada
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Molecular mechanisms for biosynthesis and assembly of nutritionally important very long chain polyunsaturated fatty acids in microorganisms. Prog Lipid Res 2020; 79:101047. [DOI: 10.1016/j.plipres.2020.101047] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/29/2020] [Accepted: 06/09/2020] [Indexed: 12/23/2022]
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Recent advances in functional analysis of polyunsaturated fatty acid synthases. Curr Opin Chem Biol 2020; 59:30-36. [PMID: 32442859 DOI: 10.1016/j.cbpa.2020.04.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/12/2020] [Accepted: 04/16/2020] [Indexed: 01/23/2023]
Abstract
Polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid, eicosapentaenoic acid, and arachidonic acid are essential fatty acids for humans. PUFAs are biosynthesized by either desaturases/elongases from oleic acid or PUFA synthases from acetyl units. PUFA synthases are composed of three or four subunits, and each creates a specific PUFA even though the multiple catalytic domains in each subunit are very similar. We recently dissected these PUFA synthases by in vivo and in vitro experiments and elucidated how the enzymes control PUFA profiles. Moreover, for the first time, we converted a practical microalgal docosahexaenoic acid synthase into an eicosapentaenoic acid synthase based on the results.
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Xie X, Meesapyodsuk D, Qiu X. Enhancing oil production in Arabidopsis through expression of a ketoacyl-ACP synthase domain of the PUFA synthase from Thraustochytrium. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:172. [PMID: 31297160 PMCID: PMC6599236 DOI: 10.1186/s13068-019-1514-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 06/21/2019] [Indexed: 06/01/2023]
Abstract
BACKGROUND Plant seed oil is an important bioresource for human food and animal feed, as well as industrial bioproducts. Therefore, increasing oil content in seeds has been one of the primary targets in the breeding programs of oilseed crops. Thraustochytrium is a marine protist that can produce a high level of very long-chain polyunsaturated fatty acids (VLCPUFAs) using a PUFA synthase, a polyketide synthase-like fatty acid synthase with multiple catalytic domains. Our previous study showed that a KS domain from the synthase could complement an Escherichia coli mutant defective in β-ketoacyl-ACP synthase I (FabB) and increase the total fatty acid production. In this study, this KS domain from the PUFA synthase was further functionally analyzed in Arabidopsis thaliana for the capacity of oil production. RESULTS The plastidial expression of the KS domain could complement the defective phenotypes of a KASI knockout mutant generated by CRISPR/Cas9. Seed-specific expression of the domain in wild-type Arabidopsis significantly increased seed weight and seed oil, and altered the unsaturation level of fatty acids in seeds, as well as promoted seed germination and early seedling growth. CONCLUSIONS The condensation process of fatty acid biosynthesis in plants is a limiting step, and overexpression of the KS domain from a PUFA synthase of microbial origin offers a new strategy to increase oil production in oilseed plants.
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Affiliation(s)
- Xi Xie
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8 Canada
| | - Dauenpen Meesapyodsuk
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8 Canada
| | - Xiao Qiu
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8 Canada
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Sun XM, Ren LJ, Zhao QY, Ji XJ, Huang H. Enhancement of lipid accumulation in microalgae by metabolic engineering. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:552-566. [DOI: 10.1016/j.bbalip.2018.10.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 07/30/2018] [Accepted: 10/05/2018] [Indexed: 01/08/2023]
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Sun XM, Ren LJ, Bi ZQ, Ji XJ, Zhao QY, Huang H. Adaptive evolution of microalgae Schizochytrium sp. under high salinity stress to alleviate oxidative damage and improve lipid biosynthesis. BIORESOURCE TECHNOLOGY 2018; 267:438-444. [PMID: 30032058 DOI: 10.1016/j.biortech.2018.07.079] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 07/13/2018] [Accepted: 07/14/2018] [Indexed: 05/09/2023]
Abstract
Lipid accumulation of Schizochytrium sp. can be induced by stress condition, but this stress-induction usually reduce cell growth and cause oxidative damage, which can eventually lower the lipid yield. Here, adaptive laboratory evolution (ALE) combined high salinity was performed to enhance the antioxidant system and lipid accumulation. The final strain ALE150, which was obtained after 150 days, showed a maximal cell dry weight (CDW) of 134.5 g/L and lipid yield of 80.14 g/L, representing a 32.7 and 53.31% increase over the starting strain, respectively. Moreover, ALE150 exhibited an overall higher total antioxidant capacity (T-AOC) and lower reactive oxygen species (ROS) levels than the starting strain. Furthermore, the regulatory mechanisms responsible for the improved performance of ALE150 were analyzed by transcriptomic analysis. Genes related to the antioxidant enzymes and central carbon metabolism were up-regulation. Moreover, the metabolic fluxes towards the fatty acid synthase (FAS) and polyketide synthase (PKS) pathways were also changed.
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Affiliation(s)
- Xiao-Man Sun
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| | - Lu-Jing Ren
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), People's Republic of China.
| | - Zhi-Qian Bi
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| | - Xiao-Jun Ji
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), People's Republic of China
| | - Quan-Yu Zhao
- School of Pharmaceutical Sciences, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China
| | - He Huang
- School of Pharmaceutical Sciences, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing 211816, People's Republic of China; State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5 Xinmofan Road, Nanjing 210009, People's Republic of China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), People's Republic of China
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Xie X, Meesapyodsuk D, Qiu X. Functional analysis of the dehydratase domains of a PUFA synthase from Thraustochytrium in Escherichia coli. Appl Microbiol Biotechnol 2017; 102:847-856. [PMID: 29177940 DOI: 10.1007/s00253-017-8635-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 10/23/2017] [Accepted: 11/07/2017] [Indexed: 01/03/2023]
Abstract
Thraustochytrium sp. 26185, a unicellular marine protist, synthesizes docosahexaenoic acid, an omega-3 very long chain polyunsaturated fatty acid (VLC-PUFAs), by a polyunsaturated fatty acid (PUFA) synthase comprising three large subunits with multiple catalytic dehydratase (DH) domains critical for introducing double bonds at the specific position of fatty acids. To investigate functions of these DH domains, one DH domain from subunit-A and two DH domains from subunit-C of the PUFA synthase were dissected and expressed as stand-alone enzymes in Escherichia coli. The results showed that all these DH domains could complement the defective phenotype of a E. coli FabA temperature sensitive mutant, despite they have only modest sequence similarity with FabA, indicating they can function as 3-hydroxyacyl-ACP dehydratase for the biosynthesis of unsaturated fatty acids in E. coli. Site-directed mutagenesis analysis confirmed the authenticity of active site residues in these domains. In addition, overexpression of the three domains in a wild type E. coli strain resulted in the substantial alteration of fatty acid profiles including productions and ratio of unsaturated to saturated fatty acids. A combination of evidences from sequence comparison, functional expression, and mutagenesis analysis suggest that the DH domain from subunit-A is similar to DH domains from polyketide synthases, while the DH domains from subunit-C are more comparable to E. coli FabA in catalytic functions. Successful complementation and functional expression of the embedded DH domains from the PUFA synthase in E. coli is an important step towards for elucidating the molecular mechanism in the biosynthesis of VLC-PUFAs in Thraustochytrium.
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Affiliation(s)
- Xi Xie
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5A8, Canada
| | - Dauenpen Meesapyodsuk
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5A8, Canada
| | - Xiao Qiu
- Department of Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5A8, Canada.
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