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Muthan B, Wang J, Welti R, Kosma DK, Yu L, Deo B, Khatiwada S, Vulavala VKR, Childs KL, Xu C, Durrett TP, Sanjaya SA. Mechanisms of Spirodela polyrhiza tolerance to FGD wastewater-induced heavy-metal stress: Lipidomics, transcriptomics, and functional validation. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:133951. [PMID: 38492385 DOI: 10.1016/j.jhazmat.2024.133951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 02/28/2024] [Accepted: 03/01/2024] [Indexed: 03/18/2024]
Abstract
Unlike terrestrial angiosperm plants, the freshwater aquatic angiosperm duckweed (Spirodela polyrhiza) grows directly in water and has distinct responses to heavy-metal stress. Plantlets accumulate metabolites, including lipids and carbohydrates, under heavy-metal stress, but how they balance metabolite levels is unclear, and the gene networks that mediate heavy-metal stress responses remain unknown. Here, we show that heavy-metal stress induced by flue gas desulfurization (FGD) wastewater reduces chlorophyll contents, inhibits growth, reduces membrane lipid biosynthesis, and stimulates membrane lipid degradation in S. polyrhiza, leading to triacylglycerol and carbohydrate accumulation. In FGD wastewater-treated plantlets, the degraded products of monogalactosyldiacylglycerol, primarily polyunsaturated fatty acids (18:3), were incorporated into triacylglycerols. Genes involved in early fatty acid biosynthesis, β-oxidation, and lipid degradation were upregulated while genes involved in cuticular wax biosynthesis were downregulated by treatment. The transcription factor gene WRINKLED3 (SpWRI3) was upregulated in FGD wastewater-treated plantlets, and its ectopic expression increased tolerance to FGD wastewater in transgenic Arabidopsis (Arabidopsis thaliana). Transgenic Arabidopsis plants showed enhanced glutathione and lower malondialdehyde contents under stress, suggesting that SpWRI3 functions in S. polyrhiza tolerance of FGD wastewater-induced heavy-metal stress. These results provide a basis for improving heavy metal-stress tolerance in plants for industrial applications.
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Affiliation(s)
- Bagyalakshmi Muthan
- Agricultural and Environmental Research Station and Energy and Environmental Science Institute, West Virginia State University, Institute, WV 25112-1000, USA
| | - Jie Wang
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Ruth Welti
- Division of Biology, Kansas State University, Manhattan, KS 66506-4901, USA
| | - Dylan K Kosma
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA
| | - Linhui Yu
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA; State Key Laboratory of Crop Stress Biology for Arid Areas and Institute of Future Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Bikash Deo
- Department of Biology, Agricultural and Environmental Research Station and Energy and Environmental Science Institute, West Virginia State University, Institute, WV 25112-1000, USA
| | - Subhiksha Khatiwada
- Department of Biology, Agricultural and Environmental Research Station and Energy and Environmental Science Institute, West Virginia State University, Institute, WV 25112-1000, USA
| | - Vijaya K R Vulavala
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA
| | - Kevin L Childs
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Changcheng Xu
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Timothy P Durrett
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Sanju A Sanjaya
- Department of Biology, Agricultural and Environmental Research Station and Energy and Environmental Science Institute, West Virginia State University, Institute, WV 25112-1000, USA.
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Cao VD, Luo G, Korynta S, Liu H, Liang Y, Shanklin J, Altpeter F. Intron-mediated enhancement of DIACYLGLYCEROL ACYLTRANSFERASE1 expression in energycane promotes a step change for lipid accumulation in vegetative tissues. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:153. [PMID: 37838699 PMCID: PMC10576891 DOI: 10.1186/s13068-023-02393-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 09/09/2023] [Indexed: 10/16/2023]
Abstract
BACKGROUND Metabolic engineering for hyperaccumulation of lipids in vegetative tissues is a novel strategy for enhancing energy density and biofuel production from biomass crops. Energycane is a prime feedstock for this approach due to its high biomass production and resilience under marginal conditions. DIACYLGLYCEROL ACYLTRANSFERASE (DGAT) catalyzes the last and only committed step in the biosynthesis of triacylglycerol (TAG) and can be a rate-limiting enzyme for the production of TAG. RESULTS In this study, we explored the effect of intron-mediated enhancement (IME) on the expression of DGAT1 and resulting accumulation of TAG and total fatty acid (TFA) in leaf and stem tissues of energycane. To maximize lipid accumulation these evaluations were carried out by co-expressing the lipogenic transcription factor WRINKLED1 (WRI1) and the TAG protect factor oleosin (OLE1). Including an intron in the codon-optimized TmDGAT1 elevated the accumulation of its transcript in leaves by seven times on average based on 5 transgenic lines for each construct. Plants with WRI1 (W), DGAT1 with intron (Di), and OLE1 (O) expression (WDiO) accumulated TAG up to a 3.85% of leaf dry weight (DW), a 192-fold increase compared to non-modified energycane (WT) and a 3.8-fold increase compared to the highest accumulation under the intron-less gene combination (WDO). This corresponded to TFA accumulation of up to 8.4% of leaf dry weight, a 2.8-fold or 6.1-fold increase compared to WDO or WT, respectively. Co-expression of WDiO resulted in stem accumulations of TAG up to 1.14% of DW or TFA up to 2.08% of DW that exceeded WT by 57-fold or 12-fold and WDO more than twofold, respectively. Constitutive expression of these lipogenic "push pull and protect" factors correlated with biomass reduction. CONCLUSIONS Intron-mediated enhancement (IME) of the expression of DGAT resulted in a step change in lipid accumulation of energycane and confirmed that under our experimental conditions it is rate limiting for lipid accumulation. IME should be applied to other lipogenic factors and metabolic engineering strategies. The findings from this study may be valuable in developing a high biomass feedstock for commercial production of lipids and advanced biofuels.
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Affiliation(s)
- Viet Dang Cao
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Gainesville, FL, USA
| | - Guangbin Luo
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Gainesville, FL, USA
| | - Shelby Korynta
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Gainesville, FL, USA
| | - Hui Liu
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Upton, NY, USA
| | - Yuanxue Liang
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Upton, NY, USA
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA.
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Upton, NY, USA.
- Biosciences Department, Brookhaven National Laboratory, Upton, NY, USA.
| | - Fredy Altpeter
- Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA.
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, Gainesville, FL, USA.
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Dharmateja P, Yadav R, Kumar M, Babu P, Jain N, Mandal PK, Pandey R, Shrivastava M, Gaikwad KB, Bainsla NK, Tomar V, Sugumar S, Saifi N, Ranjan R. Genome-wide association studies reveal putative QTLs for physiological traits under contrasting phosphorous conditions in wheat (Triticum aestivum L.). Front Genet 2022; 13:984720. [DOI: 10.3389/fgene.2022.984720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 10/17/2022] [Indexed: 11/13/2022] Open
Abstract
A Genome-wide association (GWAS) study was conducted for phosphorous (P)-use responsive physiological traits in bread wheat at the seedling stage under contrasting P regimes. A panel of 158 diverse advanced breeding lines and released varieties, and a set of 10,800 filtered single nucleotide polymorphism (SNP) markers were used to study marker-trait associations over the eight shoot traits. Principle component analysis separated the two environments (P regimes) because of the differential response of the traits indicating the essentiality of the separate breeding programmes for each environment. Significant variations for genotypic, environmental, and genotype × environment (GEI) effects were observed for all the traits in the combined analysis of variance with moderately high broad sense heritability traits (0.50–0.73). With the different algorithms of association mapping viz., BLINK, FarmCPU, and MLM, 38 unique QTLs under non-limiting P (NLP) and 45 QTLs for limiting P (LP) conditions for various shoot traits were identified. Some of these QTLs were captured by all three algorithms. Interestingly, a Q.iari.dt.sdw.1 on chromosome 1D was found to explain the significant variations in three important physiological traits under non-limiting phosphorus (NLP) conditions. We identified the putative candidate genes for QTLs namely Q.iari.dt.chl.1, Q.iari.dt.sdw.16, Q.iari.dt.sdw.9 and Q.iari.dt.tpc.1 which are potentially involved in the mechanism regulating phosphorus use efficiency through improved P absorption due to improved root architectural traits and better mobilization such as sulfotransferase involved in postembryonic root development, WALLS ARE THIN1 (WAT1), a plant-specific protein that facilitates auxin export; lectin receptor-like kinase essentially involved in plant development, stress response during germination and lateral root development and F-box component of the SKP-Cullin-F box E3 ubiquitin ligase complex and strigolactone signal perception. Expression profiling of putative genes located in identified genomic regions against the wheat expression atlas revealed their significance based on the expression of these genes for stress response and growth development processes in wheat. Our results thus provide an important insight into understanding the genetic basis for improving PUE under phosphorus stress conditions and can shape the future breeding programme by developing and integrating molecular markers for these difficult-to-score important traits.
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Luo G, Cao VD, Kannan B, Liu H, Shanklin J, Altpeter F. Metabolic engineering of energycane to hyperaccumulate lipids in vegetative biomass. BMC Biotechnol 2022; 22:24. [PMID: 36042455 PMCID: PMC9425976 DOI: 10.1186/s12896-022-00753-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 08/18/2022] [Indexed: 11/24/2022] Open
Abstract
Background The metabolic engineering of high-biomass crops for lipid production in their vegetative biomass has recently been proposed as a strategy to elevate energy density and lipid yields for biodiesel production. Energycane and sugarcane are highly polyploid, interspecific hybrids between Saccharum officinarum and Saccharum spontaneum that differ in the amount of ancestral contribution to their genomes. This results in greater biomass yield and persistence in energycane, which makes it the preferred target crop for biofuel production. Results Here, we report on the hyperaccumulation of triacylglycerol (TAG) in energycane following the overexpression of the lipogenic factors Diacylglycerol acyltransferase1-2 (DGAT1-2) and Oleosin1 (OLE1) in combination with RNAi suppression of SUGAR-DEPENDENT1 (SDP1) and Trigalactosyl diacylglycerol1 (TGD1). TAG accumulated up to 1.52% of leaf dry weight (DW,) a rate that was 30-fold that of non-modified energycane, in addition to almost doubling the total fatty acid content in leaves to 4.42% of its DW. Pearson’s correlation analysis showed that the accumulation of TAG had the highest correlation with the expression level of ZmDGAT1-2, followed by the level of RNAi suppression for SDP1. Conclusions This is the first report on the metabolic engineering of energycane and demonstrates that this resilient, high-biomass crop is an excellent target for the further optimization of the production of lipids from vegetative tissues. Supplementary Information The online version contains supplementary material available at 10.1186/s12896-022-00753-7.
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Affiliation(s)
- Guangbin Luo
- Plant Molecular and Cellular Biology Program, Agronomy Department, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
| | - Viet Dang Cao
- Plant Molecular and Cellular Biology Program, Agronomy Department, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
| | - Baskaran Kannan
- Plant Molecular and Cellular Biology Program, Agronomy Department, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA
| | - Hui Liu
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA.
| | - Fredy Altpeter
- Plant Molecular and Cellular Biology Program, Agronomy Department, Genetics Institute, University of Florida, IFAS, Gainesville, FL, USA.
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Chen G, Harwood JL, Lemieux MJ, Stone SJ, Weselake RJ. Acyl-CoA:diacylglycerol acyltransferase: Properties, physiological roles, metabolic engineering and intentional control. Prog Lipid Res 2022; 88:101181. [PMID: 35820474 DOI: 10.1016/j.plipres.2022.101181] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/31/2022] [Accepted: 07/04/2022] [Indexed: 12/15/2022]
Abstract
Acyl-CoA:diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) catalyzes the last reaction in the acyl-CoA-dependent biosynthesis of triacylglycerol (TAG). DGAT activity resides mainly in membrane-bound DGAT1 and DGAT2 in eukaryotes and bifunctional wax ester synthase-diacylglycerol acyltransferase (WSD) in bacteria, which are all membrane-bound proteins but exhibit no sequence homology to each other. Recent studies also identified other DGAT enzymes such as the soluble DGAT3 and diacylglycerol acetyltransferase (EaDAcT), as well as enzymes with DGAT activities including defective in cuticular ridges (DCR) and steryl and phytyl ester synthases (PESs). This review comprehensively discusses research advances on DGATs in prokaryotes and eukaryotes with a focus on their biochemical properties, physiological roles, and biotechnological and therapeutic applications. The review begins with a discussion of DGAT assay methods, followed by a systematic discussion of TAG biosynthesis and the properties and physiological role of DGATs. Thereafter, the review discusses the three-dimensional structure and insights into mechanism of action of human DGAT1, and the modeled DGAT1 from Brassica napus. The review then examines metabolic engineering strategies involving manipulation of DGAT, followed by a discussion of its therapeutic applications. DGAT in relation to improvement of livestock traits is also discussed along with DGATs in various other eukaryotic organisms.
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Affiliation(s)
- Guanqun Chen
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada.
| | - John L Harwood
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Membrane Protein Disease Research Group, Edmonton T6G 2H7, Canada
| | - Scot J Stone
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
| | - Randall J Weselake
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6H 2P5, Canada
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Hatanaka T, Tomita Y, Matsuoka D, Sasayama D, Fukayama H, Azuma T, Soltani Gishini MF, Hildebrand D. Different acyl-CoA:diacylglycerol acyltransferases vary widely in function, and a targeted amino acid substitution enhances oil accumulation. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:3030-3043. [PMID: 35560190 DOI: 10.1093/jxb/erac084] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 03/02/2022] [Indexed: 06/15/2023]
Abstract
Triacylglycerols (TAGs) are the major component of plant storage lipids such as oils. Acyl-CoA:diacylglycerol acyltransferase (DGAT) catalyzes the final step of the Kennedy pathway, and is mainly responsible for plant oil accumulation. We previously found that the activity of Vernonia DGAT1 was distinctively higher than that of Arabidopsis and soybean DGAT1 in a yeast microsome assay. In this study, the DGAT1 cDNAs of Arabidopsis, Vernonia, soybean, and castor bean were introduced into Arabidopsis. All Vernonia DGAT1-expressing lines showed a significantly higher oil content (49% mean increase compared with the wild-type) followed by soybean and castor bean. Most Arabidopsis DGAT1-overexpressing lines did not show a significant increase. In addition to these four DGAT1 genes, sunflower, Jatropha, and sesame DGAT1 genes were introduced into a TAG biosynthesis-defective yeast mutant. In the yeast expression culture, DGAT1s from Arabidopsis, castor bean, and soybean only slightly increased the TAG content; however, DGAT1s from Vernonia, sunflower, Jatropha, and sesame increased TAG content >10-fold more than the former three DGAT1s. Three amino acid residues were characteristically common in the latter four DGAT1s. Using soybean DGAT1, these amino acid substitutions were created by site-directed mutagenesis and substantially increased the TAG content.
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Affiliation(s)
- Tomoko Hatanaka
- Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Yoshiki Tomita
- Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Daisuke Matsuoka
- Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Daisuke Sasayama
- Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Hiroshi Fukayama
- Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Tetsushi Azuma
- Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Mohammad Fazel Soltani Gishini
- Department of Production Engineering and Plant Genetics, Faculty of Sciences and Agricultural Engineering, Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran
| | - David Hildebrand
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
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7
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Panda S, Kazachkova Y, Aharoni A. Catch-22 in specialized metabolism: balancing defense and growth. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:6027-6041. [PMID: 34293097 DOI: 10.1093/jxb/erab348] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 07/21/2021] [Indexed: 05/25/2023]
Abstract
Plants are unsurpassed biochemists that synthesize a plethora of molecules in response to an ever-changing environment. The majority of these molecules, considered as specialized metabolites, effectively protect the plant against pathogens and herbivores. However, this defense most probably comes at a great expense, leading to reduction of growth (known as the 'growth-defense trade-off'). Plants employ several strategies to reduce the high metabolic costs associated with chemical defense. Production of specialized metabolites is tightly regulated by a network of transcription factors facilitating its fine-tuning in time and space. Multifunctionality of specialized metabolites-their effective recycling system by re-using carbon, nitrogen, and sulfur, thus re-introducing them back to the primary metabolite pool-allows further cost reduction. Spatial separation of biosynthetic enzymes and their substrates, and sequestration of potentially toxic substances and conversion to less toxic metabolite forms are the plant's solutions to avoid the detrimental effects of metabolites they produce as well as to reduce production costs. Constant fitness pressure from herbivores, pathogens, and abiotic stressors leads to honing of specialized metabolite biosynthesis reactions to be timely, efficient, and metabolically cost-effective. In this review, we assess the costs of production of specialized metabolites for chemical defense and the different plant mechanisms to reduce the cost of such metabolic activity in terms of self-toxicity and growth.
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Affiliation(s)
- Sayantan Panda
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
- Gilat Research Center, Agricultural Research Organization, Negev, Israel
| | - Yana Kazachkova
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Asaph Aharoni
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
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Zhang Y, Ye Y, Bai F, Liu J. The oleaginous astaxanthin-producing alga Chromochloris zofingiensis: potential from production to an emerging model for studying lipid metabolism and carotenogenesis. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:119. [PMID: 33992124 PMCID: PMC8126118 DOI: 10.1186/s13068-021-01969-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/07/2021] [Indexed: 05/05/2023]
Abstract
The algal lipids-based biodiesel, albeit having advantages over plant oils, still remains high in the production cost. Co-production of value-added products with lipids has the potential to add benefits and is thus believed to be a promising strategy to improve the production economics of algal biodiesel. Chromochloris zofingiensis, a unicellular green alga, has been considered as a promising feedstock for biodiesel production because of its robust growth and ability of accumulating high levels of triacylglycerol under multiple trophic conditions. This alga is also able to synthesize high-value keto-carotenoids and has been cited as a candidate producer of astaxanthin, the strongest antioxidant found in nature. The concurrent accumulation of triacylglycerol and astaxanthin enables C. zofingiensis an ideal cell factory for integrated production of the two compounds and has potential to improve algae-based production economics. Furthermore, with the advent of chromosome-level whole genome sequence and genetic tools, C. zofingiensis becomes an emerging model for studying lipid metabolism and carotenogenesis. In this review, we summarize recent progress on the production of triacylglycerol and astaxanthin by C. zofingiensis. We also update our understanding in the distinctive molecular mechanisms underlying lipid metabolism and carotenogenesis, with an emphasis on triacylglycerol and astaxanthin biosynthesis and crosstalk between the two pathways. Furthermore, strategies for trait improvements are discussed regarding triacylglycerol and astaxanthin synthesis in C. zofingiensis.
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Affiliation(s)
- Yu Zhang
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Ying Ye
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Fan Bai
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Jin Liu
- Laboratory for Algae Biotechnology and Innovation, College of Engineering, Peking University, Beijing, 100871, China.
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Xu C, Fan J, Shanklin J. Metabolic and functional connections between cytoplasmic and chloroplast triacylglycerol storage. Prog Lipid Res 2020; 80:101069. [DOI: 10.1016/j.plipres.2020.101069] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 10/23/2020] [Accepted: 10/24/2020] [Indexed: 12/14/2022]
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10
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Yin Y, Guo Z, Chen K, Tian T, Tan J, Chen X, Chen J, Yang B, Tang S, Peng K, Liu S, Liang Y, Zhang K, Yu L, Li M. Ultra-high α-linolenic acid accumulating developmental defective embryo was rescued by lysophosphatidic acid acyltransferase 2. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:2151-2167. [PMID: 32573846 DOI: 10.1111/tpj.14889] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 06/01/2020] [Accepted: 06/05/2020] [Indexed: 05/20/2023]
Abstract
For decades, genetic engineering approaches to produce unusual fatty acids (UFAs) in crops has reached a bottleneck, including reduced seed oil production and seed vigor. Currently, plant models in the field of research are primarily used to investigate defects in oil production and seedling development, while the role of UFAs in embryonic developmental defects remains unknown. In this study, we developed a transgenic Arabidopsis plant model, in which the embryo exhibits severely wrinkled appearance owing to α-linolenic acid (ALA) accumulation. RNA-sequencing analysis in the defective embryo suggested that brassinosteroid synthesis, FA synthesis and photosynthesis were inhibited, while FA degradation, endoplasmic reticulum stress and oxidative stress were activated. Lipidomics analysis showed that ultra-accumulated ALA is released from phosphatidylcholine as a free FA in cells, inducing severe endoplasmic reticulum and oxidative stress. Furthermore, we identified that overexpression of lysophosphatidic acid acyltransferase 2 rescued the defective phenotype. In the rescue line, the pool capacity of the Kennedy pathway was increased, and the esterification of ALA indirectly to triacylglycerol was enhanced to avoid stress. This study provides a plant model that aids in understanding the molecular mechanism of embryonic developmental defects and generates strategies to produce higher levels of UFAs.
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Affiliation(s)
- Yongtai Yin
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
- Hubei Key Laboratory of Economic Forest Germplasm Improvement and Resource Comprehensive Utilization, Hubei Collaborative Innovation Center for the Characteristic Resources Exploitation of Dabie Mountains, Huanggang Normal University, Huanggang, 438000, China
| | - Zhenyi Guo
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Kang Chen
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Tian Tian
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jiajun Tan
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Xinfeng Chen
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jing Chen
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Bing Yang
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Shuyan Tang
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Kangfu Peng
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Si Liu
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yu Liang
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Kai Zhang
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Longjiang Yu
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Maoteng Li
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
- Hubei Key Laboratory of Economic Forest Germplasm Improvement and Resource Comprehensive Utilization, Hubei Collaborative Innovation Center for the Characteristic Resources Exploitation of Dabie Mountains, Huanggang Normal University, Huanggang, 438000, China
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Pfaff J, Denton AK, Usadel B, Pfaff C. Phosphate starvation causes different stress responses in the lipid metabolism of tomato leaves and roots. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158763. [DOI: 10.1016/j.bbalip.2020.158763] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 06/15/2020] [Accepted: 07/03/2020] [Indexed: 12/17/2022]
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12
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Correa SM, Fernie AR, Nikoloski Z, Brotman Y. Towards model-driven characterization and manipulation of plant lipid metabolism. Prog Lipid Res 2020; 80:101051. [PMID: 32640289 DOI: 10.1016/j.plipres.2020.101051] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 06/20/2020] [Accepted: 06/21/2020] [Indexed: 01/09/2023]
Abstract
Plant lipids have versatile applications and provide essential fatty acids in human diet. Therefore, there has been a growing interest to better characterize the genetic basis, regulatory networks, and metabolic pathways that shape lipid quantity and composition. Addressing these issues is challenging due to context-specificity of lipid metabolism integrating environmental, developmental, and tissue-specific cues. Here we systematically review the known metabolic pathways and regulatory interactions that modulate the levels of storage lipids in oilseeds. We argue that the current understanding of lipid metabolism provides the basis for its study in the context of genome-wide plant metabolic networks with the help of approaches from constraint-based modeling and metabolic flux analysis. The focus is on providing a comprehensive summary of the state-of-the-art of modeling plant lipid metabolic pathways, which we then contrast with the existing modeling efforts in yeast and microalgae. We then point out the gaps in knowledge of lipid metabolism, and enumerate the recent advances of using genome-wide association and quantitative trait loci mapping studies to unravel the genetic regulations of lipid metabolism. Finally, we offer a perspective on how advances in the constraint-based modeling framework can propel further characterization of plant lipid metabolism and its rational manipulation.
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Affiliation(s)
- Sandra M Correa
- Genetics of Metabolic Traits Group, Max Planck Institute for Molecular Plant Physiology, Potsdam 14476, Germany; Department of Life Sciences, Ben-Gurion University of the Negev, 8410501 Beer-Sheva, Israel; Departamento de Ciencias Exactas y Naturales, Universidad de Antioquia, Medellín 050010, Colombia.
| | - Alisdair R Fernie
- Central Metabolism Group, Max Planck Institute for Molecular Plant Physiology, Potsdam 14476, Germany; Center of Plant Systems Biology and Biotechnology, Plovdiv, Bulgaria
| | - Zoran Nikoloski
- Center of Plant Systems Biology and Biotechnology, Plovdiv, Bulgaria; Bioinformatics, Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany; Systems Biology and Mathematical Modelling Group, Max Planck Institute for Molecular Plant Physiology, Potsdam-Golm 14476, Germany.
| | - Yariv Brotman
- Genetics of Metabolic Traits Group, Max Planck Institute for Molecular Plant Physiology, Potsdam 14476, Germany; Department of Life Sciences, Ben-Gurion University of the Negev, 8410501 Beer-Sheva, Israel
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13
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Zienkiewicz K, Zienkiewicz A. Degradation of Lipid Droplets in Plants and Algae-Right Time, Many Paths, One Goal. FRONTIERS IN PLANT SCIENCE 2020; 11:579019. [PMID: 33014002 PMCID: PMC7509404 DOI: 10.3389/fpls.2020.579019] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/24/2020] [Indexed: 05/05/2023]
Abstract
In eukaryotic cells, lipids in the form of triacylglycerols (TAGs) are the major reservoir of cellular carbon and energy. These TAGs are packed into specialized organelles called lipid droplets (LDs). They can be found in most, if not all, types of cells, from bacteria to human. Recent data suggest that rather than being simple storage organelles, LDs are very dynamic structures at the center of cellular metabolism. This is also true in plants and algae, where LDs have been implicated in many processes including energy supply; membrane structure, function, trafficking; and signal transduction. Plant and algal LDs also play a vital role in human life, providing multiple sources of food and fuel. Thus, a lot of attention has been paid to metabolism and function of these organelles in recent years. This review summarizes the most recent advances on LDs degradation as a key process for TAGs release. While the initial knowledge on this process came from studies in oilseeds, the findings of the last decade revealed high complexity and specific mechanisms of LDs degradation in plants and algae. This includes identification of numerous novel proteins associated with LDs as well as a prominent role for autophagy in this process. This review outlines, systemizes, and discusses the most current data on LDs catabolism in plants and algae.
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14
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Haslam RP, Hamilton ML, Economou CK, Smith R, Hassall KL, Napier JA, Sayanova O. Overexpression of an endogenous type 2 diacylglycerol acyltransferase in the marine diatom Phaeodactylum tricornutum enhances lipid production and omega-3 long-chain polyunsaturated fatty acid content. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:87. [PMID: 32467729 PMCID: PMC7227059 DOI: 10.1186/s13068-020-01726-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 05/08/2020] [Indexed: 05/03/2023]
Abstract
BACKGROUND Oleaginous microalgae represent a valuable resource for the production of high-value molecules. Considering the importance of omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs) for human health and nutrition the yields of high-value eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) require significant improvement to meet demand; however, the current cost of production remains high. A promising approach is to metabolically engineer strains with enhanced levels of triacylglycerols (TAGs) enriched in EPA and DHA. RESULTS Recently, we have engineered the marine diatom Phaeodactylum tricornutum to accumulate enhanced levels of DHA in TAG. To further improve the incorporation of omega-3 LC-PUFAs in TAG, we focused our effort on the identification of a type 2 acyl-CoA:diacylglycerol acyltransferase (DGAT) capable of improving lipid production and the incorporation of DHA in TAG. DGAT is a key enzyme in lipid synthesis. Following a diatom based in vivo screen of candidate DGATs, a native P. tricornutum DGAT2B was taken forward for detailed characterisation. Overexpression of the endogenous P. tricornutum DGAT2B was confirmed by qRT-PCR and the transgenic strain grew successfully in comparison to wildtype. PtDGAT2B has broad substrate specificity with preferences for C16 and LC-PUFAs acyl groups. Moreover, the overexpression of an endogenous DGAT2B resulted in higher lipid yields and enhanced levels of DHA in TAG. Furthermore, a combined overexpression of the endogenous DGAT2B and ectopic expression of a Δ5-elongase showed how iterative metabolic engineering can be used to increase DHA and TAG content, irrespective of nitrogen treatment. CONCLUSION This study provides further insight into lipid metabolism in P. tricornutum and suggests a metabolic engineering approach for the efficient production of EPA and DHA in microalgae.
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Affiliation(s)
- Richard P. Haslam
- Department of Plant Sciences, Rothamsted Research, Harpenden, Herts AL5 2JQ UK
| | - Mary L. Hamilton
- Department of Plant Sciences, Rothamsted Research, Harpenden, Herts AL5 2JQ UK
- St Albans Girls School, St Albans, Hertfordshire, AL3 6DB UK
| | - Chloe K. Economou
- Department of Plant Sciences, Rothamsted Research, Harpenden, Herts AL5 2JQ UK
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
| | - Richard Smith
- Department of Plant Sciences, Rothamsted Research, Harpenden, Herts AL5 2JQ UK
- Algenuity, Eden Laboratory, Broadmead Road, Stewartby, BEDS, Bedford, MK43 9ND UK
| | - Kirsty L. Hassall
- Department of Computational and Analytical Sciences, Rothamsted Research, Harpenden, Herts AL5 2JQ UK
| | - Johnathan A. Napier
- Department of Plant Sciences, Rothamsted Research, Harpenden, Herts AL5 2JQ UK
| | - Olga Sayanova
- Department of Plant Sciences, Rothamsted Research, Harpenden, Herts AL5 2JQ UK
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15
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Nguyen T, Xu Y, Abdel-Hameed M, Sorensen JL, Singer SD, Chen G. Characterization of a Type-2 Diacylglycerol Acyltransferase from Haematococcus pluvialis Reveals Possible Allostery of the Recombinant Enzyme. Lipids 2019; 55:425-433. [PMID: 31879987 DOI: 10.1002/lipd.12210] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 12/09/2019] [Accepted: 12/13/2019] [Indexed: 12/24/2022]
Abstract
Haematococcus pluvialis is a green microalga used in the algal biotechnology industry that can accumulate considerable amounts of storage triacylglycerol (TAG) and astaxanthin, which is a high-value carotenoid with strong antioxidant activity, under stress conditions. Diacylglycerol acyltransferase (DGAT) catalyzes the last step of the acyl-CoA-dependent TAG biosynthesis and appears to represent a bottleneck in algal TAG formation. In this study, putative H. pluvialis DGAT2 cDNA (HpDGAT2A, B, D and E) were identified from a transcriptome database and were subjected to sequence-based in silico analyses. The coding sequences of HpDGAT2B, D, and E were then isolated and characterized through heterologous expression in a TAG-deficient Saccharomyces cerevisiae strain H1246. The expression of HpDGAT2D allowed the recovery of TAG biosynthesis in this yeast mutant, and further in vitro enzymatic assays confirmed that the recombinant HpDGAT2D possessed strong DGAT activity. Interestingly, the recombinant HpDGAT2D displayed sigmoidal kinetics in response to increasing acyl-CoA concentrations, which has not been reported in plant or algal DGAT2 in previous studies.
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Affiliation(s)
- Trinh Nguyen
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.,Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Yang Xu
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada
| | - Mona Abdel-Hameed
- Department of Chemistry, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - John L Sorensen
- Department of Chemistry, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Stacy D Singer
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB, T1J 4B1, Canada
| | - Guanqun Chen
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.,Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
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16
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Yang SU, Kim J, Kim H, Suh MC. Functional Characterization of Physcomitrella patens Glycerol-3-Phosphate Acyltransferase 9 and an Increase in Seed Oil Content in Arabidopsis by Its Ectopic Expression. PLANTS (BASEL, SWITZERLAND) 2019; 8:E284. [PMID: 31412690 PMCID: PMC6724121 DOI: 10.3390/plants8080284] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 08/12/2019] [Accepted: 08/12/2019] [Indexed: 02/04/2023]
Abstract
Since vegetable oils (usually triacylglycerol [TAG]) are extensively used as food and raw materials, an increase in storage oil content and production of valuable polyunsaturated fatty acids (PUFAs) in transgenic plants is desirable. In this study, a gene encoding glycerol-3-phosphate acyltransferase 9 (GPAT9), which catalyzes the synthesis of lysophosphatidic acid (LPA) from a glycerol-3-phosphate and acyl-CoA, was isolated from Physcomitrella patens, which produces high levels of very-long-chain PUFAs in protonema and gametophores. P. patens GPAT9 shares approximately 50%, 60%, and 70% amino acid similarity with GPAT9 from Chlamydomonas reinhardtii, Klebsormidium nitens, and Arabidopsis thaliana, respectively. PpGPAT9 transcripts were detected in both the protonema and gametophores. Fluorescent signals from the eYFP:PpGPAT9 construct were observed in the ER of Nicotiana benthamiana leaf epidermal cells. Ectopic expression of PpGPAT9 increased the seed oil content by approximately 10% in Arabidopsis. The levels of PUFAs (18:2, 18:3, and 20:2) and saturated FAs (16:0, 18:0, and 20:0) increased by 60% and 43%, respectively, in the storage oil of the transgenic seeds when compared with the wild type. The transgenic embryos with increased oil content contained larger embryonic cells than the wild type. Thus, PpGPAT9 may be a novel genetic resource to enhance storage oil yields from oilseed crops.
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Affiliation(s)
- Sun Ui Yang
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju 61186, Korea
| | - Juyoung Kim
- Department of Bioenergy Science and Technology, Chonnam National University, Gwangju 61186, Korea
| | - Hyojin Kim
- Department of Life Science, Sogang University, Seoul 04107, Korea
| | - Mi Chung Suh
- Department of Life Science, Sogang University, Seoul 04107, Korea.
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17
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Liu J, Sun Z, Mao X, Gerken H, Wang X, Yang W. Multiomics analysis reveals a distinct mechanism of oleaginousness in the emerging model alga Chromochloris zofingiensis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 98:1060-1077. [PMID: 30828893 DOI: 10.1111/tpj.14302] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 02/15/2019] [Accepted: 02/19/2019] [Indexed: 06/09/2023]
Abstract
Chromochloris zofingiensis, featured due to its capability to simultaneously synthesize triacylglycerol (TAG) and astaxanthin, is emerging as a leading candidate alga for production uses. To better understand the oleaginous mechanism of this alga, we conducted a multiomics analysis by systematically integrating time-resolved transcriptomes, lipidomes and metabolomes in response to nitrogen deprivation. The data analysis unraveled the distinct mechanism of TAG accumulation, which involved coordinated stimulation of multiple biological processes including supply of energy and reductants, carbon reallocation from protein and starch, and 'pushing' and 'pulling' carbon to TAG synthesis. Unlike the model alga Chlamydomonas, de novo fatty acid synthesis in C. zofingiensis was promoted, together with enhanced turnover of both glycolipids and phospholipids, supporting the drastic need of acyls for TAG assembly. Moreover, genomewide analysis identified many key functional enzymes and transcription factors that had engineering potential for TAG modulation. Two genes encoding glycerol-3-phosphate acyltransferase (GPAT), the first committed enzyme for TAG assembly, were found in the C. zofingiensis genome; in vivo functional characterization revealed that extrachloroplastic GPAT instead of chloroplastic GPAT played a central role in TAG synthesis. These findings illuminate distinct oleaginousness mechanisms in C. zofingiensis and pave the way towards rational manipulation of this alga to becone an emerging model for trait improvements.
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Affiliation(s)
- Jin Liu
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Zheng Sun
- International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, 201306, China
| | - Xuemei Mao
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Henri Gerken
- School of Sustainable Engineering and the Built Environment, Arizona State University Polytechnic campus, Mesa, AZ, 85212, USA
| | - Xiaofei Wang
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871, China
| | - Wenqiang Yang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
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18
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Xin Y, Shen C, She Y, Chen H, Wang C, Wei L, Yoon K, Han D, Hu Q, Xu J. Biosynthesis of Triacylglycerol Molecules with a Tailored PUFA Profile in Industrial Microalgae. MOLECULAR PLANT 2019; 12:474-488. [PMID: 30580039 DOI: 10.1016/j.molp.2018.12.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 11/29/2018] [Accepted: 12/13/2018] [Indexed: 05/06/2023]
Abstract
The composition of polyunsaturated fatty acids (PUFAs) in triacylglycerols (TAGs) is key to health benefits and for oil applications, yet the underlying genetic mechanism remains poorly understood. In this study, by in silico, ex vivo, and in vivo profiling of type-2 diacylglycerol acyltransferases (DGAT2s) in Nannochloropsis oceanica we revealed two novel PUFA-preferring enzymes that discriminate individual PUFA species in TAG assembly, with NoDGAT2J for linoleic acid (LA) and NoDGAT2K for eicosapentaenoic acid (EPA). The LA and EPA composition of TAG molecules is mediated in vivo via the functional partitioning between NoDGAT2J and 2K, both of which are localized in the chloroplast envelope. By modulating transcript abundance of the DGAT2s, an N. oceanica strain bank was created, where proportions of LA and EPA in TAG vary by 18.7-fold (between 0.21% and 3.92% dry weight) and 34.7-fold (between 0.09% and 3.12% dry weight), respectively. These findings lay the foundation for producing designer TAG molecules with tailored health benefits or for biofuel applications in industrial microalgae and higher-plant crops.
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Affiliation(s)
- Yi Xin
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chen Shen
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yiting She
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong Chen
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Cong Wang
- Core Laboratory, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Li Wei
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kangsup Yoon
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Danxiang Han
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Qiang Hu
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China
| | - Jian Xu
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong 266237, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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19
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Vanhercke T, Dyer JM, Mullen RT, Kilaru A, Rahman MM, Petrie JR, Green AG, Yurchenko O, Singh SP. Metabolic engineering for enhanced oil in biomass. Prog Lipid Res 2019; 74:103-129. [PMID: 30822461 DOI: 10.1016/j.plipres.2019.02.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/21/2019] [Accepted: 02/21/2019] [Indexed: 02/06/2023]
Abstract
The world is hungry for energy. Plant oils in the form of triacylglycerol (TAG) are one of the most reduced storage forms of carbon found in nature and hence represent an excellent source of energy. The myriad of applications for plant oils range across foods, feeds, biofuels, and chemical feedstocks as a unique substitute for petroleum derivatives. Traditionally, plant oils are sourced either from oilseeds or tissues surrounding the seed (mesocarp). Most vegetative tissues, such as leaves and stems, however, accumulate relatively low levels of TAG. Since non-seed tissues constitute the majority of the plant biomass, metabolic engineering to improve their low-intrinsic TAG-biosynthetic capacity has recently attracted significant attention as a novel, sustainable and potentially high-yielding oil production platform. While initial attempts predominantly targeted single genes, recent combinatorial metabolic engineering strategies have focused on the simultaneous optimization of oil synthesis, packaging and degradation pathways (i.e., 'push, pull, package and protect'). This holistic approach has resulted in dramatic, seed-like TAG levels in vegetative tissues. With the first proof of concept hurdle addressed, new challenges and opportunities emerge, including engineering fatty acid profile, translation into agronomic crops, extraction, and downstream processing to deliver accessible and sustainable bioenergy.
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Affiliation(s)
- Thomas Vanhercke
- CSIRO Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia.
| | - John M Dyer
- USDA-ARS, US Arid-Land Agricultural Research Center, Maricopa, AZ, USA
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, ON, Canada
| | - Aruna Kilaru
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, USA
| | - Md Mahbubur Rahman
- Department of Biological Sciences, East Tennessee State University, Johnson City, TN, USA
| | - James R Petrie
- CSIRO Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia; Folear, Goulburn, NSW, Australia
| | - Allan G Green
- CSIRO Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia
| | - Olga Yurchenko
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Surinder P Singh
- CSIRO Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT, Australia
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20
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Mao X, Wu T, Kou Y, Shi Y, Zhang Y, Liu J. Characterization of type I and type II diacylglycerol acyltransferases from the emerging model alga Chlorella zofingiensis reveals their functional complementarity and engineering potential. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:28. [PMID: 30792816 PMCID: PMC6371474 DOI: 10.1186/s13068-019-1366-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/30/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND The green alga Chlorella zofingiensis has been recognized as an industrially relevant strain because of its robust growth under multiple trophic conditions and the potential for simultaneous production of triacylglycerol (TAG) and the high-value keto-carotenoid astaxanthin. Nevertheless, the mechanism of TAG synthesis remains poorly understood in C. zofingiensis. Diacylglycerol acyltransferase (DGAT) is thought to catalyze the committed step of TAG assembly in the Kennedy pathway. C. zofingiensis genome is predicted to possess eleven putative DGAT-encoding genes, the greatest number ever found in green algae, pointing to the complexity of TAG assembly in the alga. RESULTS The transcription start site of C. zofingiensis DGATs was determined by 5'-rapid amplification of cDNA ends (RACE), and their coding sequences were cloned and verified by sequencing, which identified ten DGAT genes (two type I DGATs designated as CzDGAT1A and CzDGAT1B, and eight type II DGATs designated as CzDGTT1 through CzDGTT8) and revealed that the previous gene models of seven DGATs were incorrect. Function complementation in the TAG-deficient yeast strain confirmed the functionality of most DGATs, with CzDGAT1A and CzDGTT5 having the highest activity. In vitro DGAT assay revealed that CzDGAT1A and CzDGTT5 preferred eukaryotic and prokaryotic diacylglycerols (DAGs), respectively, and had overlapping yet distinctive substrate specificity for acyl-CoAs. Subcellular co-localization experiment in tobacco leaves indicated that both CzDGAT1A and CzDGTT5 were localized at endoplasmic reticulum (ER). Upon nitrogen deprivation, TAG was drastically induced in C. zofingiensis, accompanied by a considerable up-regulation of CzDGAT1A and CzDGTT5. These two genes were probably regulated by the transcription factors (TFs) bZIP3 and MYB1, as suggested by the yeast one-hybrid assay and expression correlation. Moreover, heterologous expression of CzDGAT1A and CzDGTT5 promoted TAG accumulation and TAG yield in different hosts including yeast and oleaginous alga. CONCLUSIONS Our study represents a pioneering work on the characterization of both type I and type II C. zofingiensis DGATs by systematically integrating functional complementation, in vitro enzymatic assay, subcellular localization, yeast one-hybrid assay and overexpression in yeast and oleaginous alga. These results (1) update the gene models of C. zofingiensis DGATs, (2) shed light on the mechanism of oleaginousness in which CzDGAT1A and CzDGTT5, have functional complementarity and probably work in collaboration at ER contributing to the abundance and complexity of TAG, and (3) provide engineering targets for future trait improvement via rational manipulation of this alga as well as other industrially relevant ones.
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Affiliation(s)
- Xuemei Mao
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Tao Wu
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
- BIC-ESAT, College of Engineering, Peking University, Beijing, 100871 China
| | - Yaping Kou
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
| | - Ying Shi
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
| | - Yu Zhang
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
| | - Jin Liu
- Laboratory for Algae Biotechnology & Innovation, College of Engineering, Peking University, Beijing, 100871 China
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21
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Jia B, Xie X, Wu M, Lin Z, Yin J, lou S, Huang Y, Hu Z. Understanding the functions of endogenous DOF transcript factor in Chlamydomonas reinhardtii. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:67. [PMID: 30972144 PMCID: PMC6436238 DOI: 10.1186/s13068-019-1403-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 03/11/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND The regulation of genes related to lipid metabolism by genetic engineering is an important way to increase the accumulation of lipids in microalgae. DNA binding with one finger (DOF) is a plant-specific transcription factor in higher plants, where it regulates carbon and nitrogen metabolic pathways by regulating key genes involved in these pathways. Overexpression of DOF can increase lipid production in plants; however, it is not clear whether overexpression of DOF can increase lipids in microalgae. RESULTS In this study, we cloned a DOF transcription factor, crDOF, from Chlamydomonas reinhardtii. The sequence of this transcription factor is 1875 bp and encodes a peptide of 624 amino acids with a conserved DOF domain. Overexpression of crDOF in C. reinhardtii significantly increased the intracellular lipid content. The content of total fatty acids in the transgenic algae line Tranc-crDOF-12 was 126.01 μg/mg (dry weight), which was 23.24% higher than that of the wild type. Additionally, the content of unsaturated fatty acids in the transgenic Tranc-crDOF-12 line increased significantly. Fluorescence quantitative PCR analysis showed that in the transgenic line Tranc-crDOF-12, the expression levels of BCC1, FAT1, SQD1, MGD1, DGD1 and PGP1 genes were significantly upregulated, while the expression levels of ACP1, ACS1, CIS1 and SQD2 were downregulated. CONCLUSIONS Our results confirm that crDOF increases intracellular lipids in C. reinhardtii by regulating key genes involved in lipid metabolism. According to these findings, we propose that enhancing the lipid content in microalgae by overexpressing DOF may be achieved in other industrial strains of microalgae and be employed for the industrial production of biodiesel.
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Affiliation(s)
- Bin Jia
- Guangdong Engineering Research Center for Marine Algal Biotechnology,
Guangdong Key Laboratory of Plant Epigenetics, Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Xinfeng Xie
- Guangdong Engineering Research Center for Marine Algal Biotechnology,
Guangdong Key Laboratory of Plant Epigenetics, Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Min Wu
- Guangdong Engineering Research Center for Marine Algal Biotechnology,
Guangdong Key Laboratory of Plant Epigenetics, Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Zijie Lin
- Guangdong Engineering Research Center for Marine Algal Biotechnology,
Guangdong Key Laboratory of Plant Epigenetics, Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Jianbo Yin
- Guangdong Engineering Research Center for Marine Algal Biotechnology,
Guangdong Key Laboratory of Plant Epigenetics, Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Sulin lou
- Guangdong Engineering Research Center for Marine Algal Biotechnology,
Guangdong Key Laboratory of Plant Epigenetics, Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Ying Huang
- Guangdong Engineering Research Center for Marine Algal Biotechnology,
Guangdong Key Laboratory of Plant Epigenetics, Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences, Shenzhen University, Shenzhen, 518060 People’s Republic of China
| | - Zhangli Hu
- Guangdong Engineering Research Center for Marine Algal Biotechnology,
Guangdong Key Laboratory of Plant Epigenetics, Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Longhua Innovation Institute for Biotechnology, College of Life Sciences, Shenzhen University, Shenzhen, 518060 People’s Republic of China
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22
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Maraschin FDS, Kulcheski FR, Segatto ALA, Trenz TS, Barrientos-Diaz O, Margis-Pinheiro M, Margis R, Turchetto-Zolet AC. Enzymes of glycerol-3-phosphate pathway in triacylglycerol synthesis in plants: Function, biotechnological application and evolution. Prog Lipid Res 2019; 73:46-64. [DOI: 10.1016/j.plipres.2018.12.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 11/01/2018] [Accepted: 12/01/2018] [Indexed: 01/30/2023]
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23
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Xu Y, Caldo KMP, Pal-Nath D, Ozga J, Lemieux MJ, Weselake RJ, Chen G. Properties and Biotechnological Applications of Acyl-CoA:diacylglycerol Acyltransferase and Phospholipid:diacylglycerol Acyltransferase from Terrestrial Plants and Microalgae. Lipids 2018; 53:663-688. [PMID: 30252128 DOI: 10.1002/lipd.12081] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 12/14/2022]
Abstract
Triacylglycerol (TAG) is the major storage lipid in most terrestrial plants and microalgae, and has great nutritional and industrial value. Since the demand for vegetable oil is consistently increasing, numerous studies have been focused on improving the TAG content and modifying the fatty-acid compositions of plant seed oils. In addition, there is a strong research interest in establishing plant vegetative tissues and microalgae as platforms for lipid production. In higher plants and microalgae, TAG biosynthesis occurs via acyl-CoA-dependent or acyl-CoA-independent pathways. Diacylglycerol acyltransferase (DGAT) catalyzes the last and committed step in the acyl-CoA-dependent biosynthesis of TAG, which appears to represent a bottleneck in oil accumulation in some oilseed species. Membrane-bound and soluble forms of DGAT have been identified with very different amino-acid sequences and biochemical properties. Alternatively, TAG can be formed through acyl-CoA-independent pathways via the catalytic action of membrane-bound phospholipid:diacylglycerol acyltransferase (PDAT). As the enzymes catalyzing the terminal steps of TAG formation, DGAT and PDAT play crucial roles in determining the flux of carbon into seed TAG and thus have been considered as the key targets for engineering oil production. Here, we summarize the most recent knowledge on DGAT and PDAT in higher plants and microalgae, with the emphasis on their physiological roles, structural features, and regulation. The development of various metabolic engineering strategies to enhance the TAG content and alter the fatty-acid composition of TAG is also discussed.
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Affiliation(s)
- Yang Xu
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
| | - Kristian Mark P Caldo
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
- Department of Biochemistry, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2H7, Canada
| | - Dipasmita Pal-Nath
- French Associates Institute for Agriculture and Biotechnology of Drylands, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, 8499000, Israel
| | - Jocelyn Ozga
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2H7, Canada
| | - Randall J Weselake
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
| | - Guanqun Chen
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 116 Street and 85 Avenue, Edmonton, Alberta, T6G 2P5, Canada
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24
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Yurchenko O, Kimberlin A, Mehling M, Koo AJ, Chapman KD, Mullen RT, Dyer JM. Response of high leaf-oil Arabidopsis thaliana plant lines to biotic or abiotic stress. PLANT SIGNALING & BEHAVIOR 2018; 13:e1464361. [PMID: 29701541 PMCID: PMC6103283 DOI: 10.1080/15592324.2018.1464361] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 04/04/2018] [Accepted: 04/05/2018] [Indexed: 06/08/2023]
Abstract
Recent studies have shown that it is possible to engineer substantial increases in triacylglycerol (TAG) content in plant vegetative biomass, which offers a novel approach for increasing the energy density of food, feed, and bioenergy crops or for creating a sink for the accumulation of unusual, high-value fatty acids. However, whether or not these changes in lipid metabolism affect plant responses to biotic and/or abiotic stresses is an open question. Here we show that transgenic Arabidopsis thaliana plant lines engineered for elevated leaf oil content, as well as lines engineered for accumulation of unusual conjugated fatty acids in leaf oil, had similar short-term responses to heat stress (e.g., 3 days at 37°C) as wild-type plants, including a reduction in polyunsaturated fatty acid (PUFA)-containing polar lipids and an increase in PUFA-containing neutral lipids. At extended time periods (e.g., 14 days at 37°C), however, plant lines containing accumulated conjugated fatty acids displayed earlier senescence and plant death. Further, no-choice feeding studies demonstrated that plants with the highest leaf oil content generated cabbage looper (Trichoplusia ni) insects with significantly heavier body weights. Taken together, these results suggest that biotic and abiotic responses will be important considerations when developing and deploying high-oil-biomass crops in the field.
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Affiliation(s)
- Olga Yurchenko
- USDA-ARS, Arid-Land Agricultural Research Center, Maricopa, AZ, USA
| | - Athen Kimberlin
- Department of Biochemistry, University of Missouri, Columbia, MO, USA
| | - Marina Mehling
- USDA-ARS, Arid-Land Agricultural Research Center, Maricopa, AZ, USA
| | - Abraham J. Koo
- Department of Biochemistry, University of Missouri, Columbia, MO, USA
| | - Kent D. Chapman
- Department of Biological Sciences, BioDiscovery Institute, University of North Texas, Denton, TX, USA
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, ON, Canada
| | - John M. Dyer
- USDA-ARS, Arid-Land Agricultural Research Center, Maricopa, AZ, USA
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25
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de Abreu E Lima F, Li K, Wen W, Yan J, Nikoloski Z, Willmitzer L, Brotman Y. Unraveling lipid metabolism in maize with time-resolved multi-omics data. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:1102-1115. [PMID: 29385634 DOI: 10.1111/tpj.13833] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 01/03/2018] [Accepted: 01/04/2018] [Indexed: 05/19/2023]
Abstract
Maize is the cereal crop with the highest production worldwide, and its oil is a key energy resource. Improving the quantity and quality of maize oil requires a better understanding of lipid metabolism. To predict the function of maize genes involved in lipid biosynthesis, we assembled transcriptomic and lipidomic data sets from leaves of B73 and the high-oil line By804 in two distinct time-series experiments. The integrative analysis based on high-dimensional regularized regression yielded lipid-transcript associations indirectly validated by Gene Ontology and promoter motif enrichment analyses. The co-localization of lipid-transcript associations using the genetic mapping of lipid traits in leaves and seedlings of a B73 × By804 recombinant inbred line population uncovered 323 genes involved in the metabolism of phospholipids, galactolipids, sulfolipids and glycerolipids. The resulting association network further supported the involvement of 50 gene candidates in modulating levels of representatives from multiple acyl-lipid classes. Therefore, the proposed approach provides high-confidence candidates for experimental testing in maize and model plant species.
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Affiliation(s)
| | - Kun Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Shizishan Lu 1, 430070, Hongshan, Wuhan, China
| | - Weiwei Wen
- Max-Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam, Germany
| | - Jianbing Yan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Shizishan Lu 1, 430070, Hongshan, Wuhan, China
| | - Zoran Nikoloski
- Max-Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam, Germany
- Bioinformatics Group, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476, Potsdam, Germany
| | - Lothar Willmitzer
- Max-Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam, Germany
| | - Yariv Brotman
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheva, Israel
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26
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Cui Y, Zhao J, Wang Y, Qin S, Lu Y. Characterization and engineering of a dual-function diacylglycerol acyltransferase in the oleaginous marine diatom Phaeodactylum tricornutum. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:32. [PMID: 29449880 PMCID: PMC5806285 DOI: 10.1186/s13068-018-1029-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 01/23/2018] [Indexed: 05/03/2023]
Abstract
BACKGROUND Photosynthetic oleaginous microalgae are promising feedstocks for biofuels. Acyl-CoA:diacylglycerol acyltransferases (DGATs) represent rich sources for engineering microalgal lipid production. The principal activity of DGATs has been defined as a single-function enzyme catalyzing the esterification of diacylglycerol with acyl-CoA. RESULTS A dual-function PtWS/DGAT associated with diatom Phaeodactylum tricornutum is discovered in the current study. Distinctive to documented microalgal DGAT types, PtWS/DGAT exhibits activities of both a wax ester synthase (WS) and a DGAT. WS/DGATs are broadly distributed in microalgae, with different topology and phylogeny from those of DGAT1s, DGAT2s, and DGAT3s. In vitro and in vivo assays revealed that PtWS/DGAT, functioning as either a WS or a DGAT, exhibited a preference on saturated FA substrate. Endogenous overexpression of PtWS/DGAT demonstrated that the DGAT activity was dominant, whereas the WS activity was condition dependent and relatively minor. Compared with the wild type (WT), overexpression of PtWS/DGAT in the diatom resulted in increased levels of total lipids (TL) and triacylglycerol (TAG) regardless of nitrogen availability. The stability and scalability of the introduced traits were further investigated at a 10-L photobioreactor, where the mutant growth resembled WT, with moderately increased productivity of TL and TAG. Furthermore, the production of wax esters increased considerably (from undetectable levels to 2.83%) under nitrogen-deplete conditions. CONCLUSIONS PtWS/DGAT is a bifunctional enzyme and may serve as a promising target for the engineering of microalga-based oils and waxes for future industrial use.
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Affiliation(s)
- Yulin Cui
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003 Shandong China
| | - Jialin Zhao
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003 Shandong China
- University of Chinese Academy of Sciences, Beijing, 101408 China
| | - Yinchu Wang
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003 Shandong China
| | - Song Qin
- Key Laboratory of Coastal Biology and Biological Resource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, 264003 Shandong China
| | - Yandu Lu
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou, Hainan 570228 China
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27
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Singer SD, Weselake RJ, Acharya S. Molecular Enhancement of Alfalfa: Improving Quality Traits for Superior Livestock Performance and Reduced Environmental Impact. CROP SCIENCE 2018; 58:55-71. [PMID: 0 DOI: 10.2135/cropsci2017.07.0434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Affiliation(s)
- Stacy D. Singer
- Agriculture and Agri-Food Canada; Lethbridge Research and Development Centre; Lethbridge AB Canada T1J 4B1
| | - Randall J. Weselake
- Dep. of Agricultural, Food and Nutritional Science; Univ. of Alberta; Edmonton AB Canada T6G 2P5
| | - Surya Acharya
- Agriculture and Agri-Food Canada; Lethbridge Research and Development Centre; Lethbridge AB Canada T1J 4B1
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28
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Xin Y, Lu Y, Lee YY, Wei L, Jia J, Wang Q, Wang D, Bai F, Hu H, Hu Q, Liu J, Li Y, Xu J. Producing Designer Oils in Industrial Microalgae by Rational Modulation of Co-evolving Type-2 Diacylglycerol Acyltransferases. MOLECULAR PLANT 2017; 10:1523-1539. [PMID: 29107033 DOI: 10.1016/j.molp.2017.10.011] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/17/2017] [Accepted: 10/21/2017] [Indexed: 05/03/2023]
Abstract
Microalgal oils, depending on their degree of unsaturation, can be utilized as either nutritional supplements or fuels; thus, a feedstock with genetically designed and tunable degree of unsaturation is desirable to maximize process efficiency and product versatility. Systematic profiling of ex vivo (in yeast), in vitro, and in vivo activities of type-2 diacylglycerol acyltransferases in Nannochloropsis oceanica (NoDGAT2s or NoDGTTs), via reverse genetics, revealed that NoDGAT2A prefers saturated fatty acids (SFAs), NoDGAT2D prefers monounsaturated fatty acids (MUFAs), and NoDGAT2C exhibits the strongest activity toward polyunsaturated fatty acids (PUFAs). As NoDGAT2A, 2C, and 2D originated from the green alga, red alga, and eukaryotic host ancestral participants of secondary endosymbiosis, respectively, a mechanistic model of oleaginousness was unveiled, in which the indigenous and adopted NoDGAT2s formulated functional complementarity and specific transcript abundance ratio that underlie a rigid SFA:MUFA:PUFA hierarchy in triacylglycerol (TAG). By rationally modulating the ratio of NoDGAT2A:2C:2D transcripts, a bank of N. oceanica strains optimized for nutritional supplement or fuel production with a wide range of degree of unsaturation were created, in which proportion of SFAs, MUFAs, and PUFAs in TAG varied by 1.3-, 3.7-, and 11.2-fold, respectively. This established a novel strategy to simultaneously improve productivity and quality of oils from industrial microalgae.
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Affiliation(s)
- Yi Xin
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yandu Lu
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi-Ying Lee
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland, Baltimore County, Baltimore, MD 21202, USA
| | - Li Wei
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Jia
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qintao Wang
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongmei Wang
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fali Bai
- Core Laboratory, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hanhua Hu
- Diatom Biology Group, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qiang Hu
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jin Liu
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland, Baltimore County, Baltimore, MD 21202, USA; Institute for Food and Bioresource Engineering and Department of Energy and Resource Engineering, College of Engineering, Peking University, Beijing 100871, China.
| | - Yantao Li
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland, Baltimore County, Baltimore, MD 21202, USA.
| | - Jian Xu
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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29
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Pick U, Avidan O. Triacylglycerol is produced from starch and polar lipids in the green alga Dunaliella tertiolecta. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:4939-4950. [PMID: 28992231 PMCID: PMC5853294 DOI: 10.1093/jxb/erx280] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The halotolerant green alga Dunaliella tertiolecta accumulates starch and triacylglycerol (TAG) amounting to 70% and 10-15% of total cellular carbon, respectively, when exposed to nitrogen (N) deprivation. The purpose of this study was to clarify the inter-relationships between the biosynthesis of TAG, starch, and polar lipids (PLs) in this alga. Pulse labeling with [14C]bicarbonate was utilized to label starch and [14C]palmitic acid (PlA) to label lipids. Transfer of 14C into TAG was measured and used to calculate rates of synthesis. About two-thirds of the carbon in TAG originates from starch, and one-third is made de novo by direct CO2 assimilation. The level made from degradation of pre-formed PLs is estimated to be very small. Most of the de novo synthesis involves fatty acid transfer through PLs made during the first day of N deprivation. The results suggest that starch made by photosynthetic carbon assimilation at the early stages of N deprivation is utilized for synthesis of TAG. Trans-acylation from PLs is the second major contributor to TAG biosynthesis. The utilization of starch for TAG biosynthesis may have biotechnological applications to optimize TAG biosynthesis in algae.
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Affiliation(s)
- Uri Pick
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
- Correspondence:
| | - Omri Avidan
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
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30
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Yurchenko O, Shockey JM, Gidda SK, Silver MI, Chapman KD, Mullen RT, Dyer JM. Engineering the production of conjugated fatty acids in Arabidopsis thaliana leaves. PLANT BIOTECHNOLOGY JOURNAL 2017; 15:1010-1023. [PMID: 28083898 PMCID: PMC5506653 DOI: 10.1111/pbi.12695] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/28/2016] [Accepted: 01/05/2017] [Indexed: 05/23/2023]
Abstract
The seeds of many nondomesticated plant species synthesize oils containing high amounts of a single unusual fatty acid, many of which have potential usage in industry. Despite the identification of enzymes for unusual oxidized fatty acid synthesis, the production of these fatty acids in engineered seeds remains low and is often hampered by their inefficient exclusion from phospholipids. Recent studies have established the feasibility of increasing triacylglycerol content in plant leaves, which provides a novel approach for increasing energy density of biomass crops. Here, we determined whether the fatty acid composition of leaf oil could be engineered to accumulate unusual fatty acids. Eleostearic acid (ESA) is a conjugated fatty acid produced in seeds of the tung tree (Vernicia fordii) and has both industrial and nutritional end-uses. Arabidopsis thaliana lines with elevated leaf oil were first generated by transforming wild-type, cgi-58 or pxa1 mutants (the latter two of which contain mutations disrupting fatty acid breakdown) with the diacylglycerol acyltransferases (DGAT1 or DGAT2) and/or oleosin genes from tung. High-leaf-oil plant lines were then transformed with tung FADX, which encodes the fatty acid desaturase/conjugase responsible for ESA synthesis. Analysis of lipids in leaves revealed that ESA was efficiently excluded from phospholipids, and co-expression of tung FADX and DGAT2 promoted a synergistic increase in leaf oil content and ESA accumulation. Taken together, these results provide a new approach for increasing leaf oil content that is coupled with accumulation of unusual fatty acids. Implications for production of biofuels, bioproducts, and plant-pest interactions are discussed.
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Affiliation(s)
- Olga Yurchenko
- USDA‐ARSUS Arid‐Land Agricultural Research CenterMaricopaAZUSA
| | - Jay M. Shockey
- USDA‐ARSSouthern Regional Research CenterNew OrleansLAUSA
| | - Satinder K. Gidda
- Department of Molecular and Cellular BiologyUniversity of GuelphGuelphONCanada
| | - Maxwell I. Silver
- Department of Molecular and Cellular BiologyUniversity of GuelphGuelphONCanada
| | - Kent D. Chapman
- Department of Biological SciencesUniversity of North TexasDentonTXUSA
| | - Robert T. Mullen
- Department of Molecular and Cellular BiologyUniversity of GuelphGuelphONCanada
| | - John M. Dyer
- USDA‐ARSUS Arid‐Land Agricultural Research CenterMaricopaAZUSA
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31
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Cai Y, McClinchie E, Price A, Nguyen TN, Gidda SK, Watt SC, Yurchenko O, Park S, Sturtevant D, Mullen RT, Dyer JM, Chapman KD. Mouse fat storage-inducing transmembrane protein 2 (FIT2) promotes lipid droplet accumulation in plants. PLANT BIOTECHNOLOGY JOURNAL 2017; 15:824-836. [PMID: 27987528 PMCID: PMC5466434 DOI: 10.1111/pbi.12678] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/01/2016] [Accepted: 12/02/2016] [Indexed: 05/23/2023]
Abstract
Fat storage-inducing transmembrane protein 2 (FIT2) is an endoplasmic reticulum (ER)-localized protein that plays an important role in lipid droplet (LD) formation in animal cells. However, no obvious homologue of FIT2 is found in plants. Here, we tested the function of FIT2 in plant cells by ectopically expressing mouse (Mus musculus) FIT2 in Nicotiana tabacum suspension-cultured cells, Nicotiana benthamiana leaves and Arabidopsis thaliana plants. Confocal microscopy indicated that the expression of FIT2 dramatically increased the number and size of LDs in leaves of N. benthamiana and Arabidopsis, and lipidomics analysis and mass spectrometry imaging confirmed the accumulation of neutral lipids in leaves. FIT2 also increased seed oil content by ~13% in some stable, overexpressing lines of Arabidopsis. When expressed transiently in leaves of N. benthamiana or suspension cells of N. tabacum, FIT2 localized specifically to the ER and was often concentrated at certain regions of the ER that resembled ER-LD junction sites. FIT2 also colocalized at the ER with other proteins known to be involved in triacylglycerol biosynthesis or LD formation in plants, but not with ER resident proteins involved in electron transfer or ER-vesicle exit sites. Collectively, these results demonstrate that mouse FIT2 promotes LD accumulation in plants, a surprising functional conservation in the context of a plant cell given the apparent lack of FIT2 homologues in higher plants. These results suggest also that FIT2 expression represents an effective synthetic biology strategy for elaborating neutral lipid compartments in plant tissues for potential biofuel or bioproduct purposes.
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Affiliation(s)
- Yingqi Cai
- Center for Plant Lipid ResearchUniversity of North TexasDentonTXUSA
| | | | - Ann Price
- Center for Plant Lipid ResearchUniversity of North TexasDentonTXUSA
| | - Thuy N. Nguyen
- Department of Molecular and Cellular BiologyUniversity of GuelphGuelphONCanada
- Present address: Department of Molecular GeneticsUniversity of TorontoTorontoONCanada
| | - Satinder K. Gidda
- Department of Molecular and Cellular BiologyUniversity of GuelphGuelphONCanada
| | - Samantha C. Watt
- Department of Molecular and Cellular BiologyUniversity of GuelphGuelphONCanada
| | - Olga Yurchenko
- US Arid‐Land Agricultural Research CenterUSDA‐ARSMaricopaAZUSA
| | - Sunjung Park
- US Arid‐Land Agricultural Research CenterUSDA‐ARSMaricopaAZUSA
- Present address: Biology DepartmentCentral Arizona CollegeMaricopaAZ85138USA
| | - Drew Sturtevant
- Center for Plant Lipid ResearchUniversity of North TexasDentonTXUSA
| | - Robert T. Mullen
- Department of Molecular and Cellular BiologyUniversity of GuelphGuelphONCanada
| | - John M. Dyer
- US Arid‐Land Agricultural Research CenterUSDA‐ARSMaricopaAZUSA
| | - Kent D. Chapman
- Center for Plant Lipid ResearchUniversity of North TexasDentonTXUSA
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32
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Schüler LM, Schulze PS, Pereira H, Barreira L, León R, Varela J. Trends and strategies to enhance triacylglycerols and high-value compounds in microalgae. ALGAL RES 2017. [DOI: 10.1016/j.algal.2017.05.025] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Klaitong P, Fa-Aroonsawat S, Chungjatupornchai W. Accelerated triacylglycerol production and altered fatty acid composition in oleaginous microalga Neochloris oleoabundans by overexpression of diacylglycerol acyltransferase 2. Microb Cell Fact 2017; 16:61. [PMID: 28403867 PMCID: PMC5389083 DOI: 10.1186/s12934-017-0677-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 04/05/2017] [Indexed: 11/25/2022] Open
Abstract
Background Microalgae are promising sources of lipid triacylglycerol (TAG) for biodiesel production. However, to date, microalgal biodiesel is technically feasible, but not yet economically viable. Increasing TAG content and productivity are important to achieve economic viability of microalgal biodiesel. To increase TAG content, oleaginous microalga Neochloris oleoabundans was genetically engineered with an endogenous key enzyme diacylglycerol acyltransferase 2 (NeoDGAT2) responsible for TAG biosynthesis. Results The integration of NeoDGAT2 expression cassettes in N. oleoabundans transformant was confirmed by PCR. The neutral lipid accumulation in the transformant detected by Nile red staining was accelerated and 1.9-fold higher than in wild type; the lipid bodies in the transformant visualized under fluorescence microscope were also larger. The NeoDGAT2 transcript was two-fold higher in the transformant than wild type. Remarkably higher lipid accumulation was found in the transformant than wild type: total lipid content increased 1.6-to 2.3-fold up to 74.5 ± 4.0% dry cell weight (DCW) and total lipid productivity increased 1.6- to 3.2-fold up to 14.6 ± 2.0 mg/L/day; while TAG content increased 1.8- to 3.2-fold up to 46.1 ± 1.6% DCW and TAG productivity increased 1.6- to 4.3-fold up to 8.9 ± 1.3 mg/L/day. A significantly altered fatty acid composition was detected in the transformant compared to wild type; the levels of saturated fatty acid C16:0 increased double to 49%, whereas C18:0 was reduced triple to 6%. Long-term stability was observed in the transformant continuously maintained in solid medium over 100 generations in a period of about 4 years. Conclusions Our results demonstrate the increased TAG content and productivity in N. oleoabundans by NeoDGAT2 overexpression that may offer the first step towards making microalgae an economically feasible source for biodiesel production. The strategy for genetically improved microalga presented in this study can be applied to other microalgal species possessing desired characteristics for industrial biofuel production.
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Affiliation(s)
- Paeka Klaitong
- Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom, 73170, Thailand
| | - Sirirat Fa-Aroonsawat
- Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom, 73170, Thailand
| | - Wipa Chungjatupornchai
- Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom, 73170, Thailand.
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Abstract
Lipids and oils derived from plant and algal photosynthesis constitute much of human daily caloric intake and provide the basis for high-energy bioproducts, chemical feedstocks for countless applications, and even fossil fuels over geological time scales. Sustainable production of high-energy compounds from plants is essential to preserving fossil fuel sources and ensuring the well-being of future generations. As a result of progress in basic research on plant and algal lipid metabolism, in combination with advances in synthetic biology, we can now tailor plant lipids for desirable biological, physical, and chemical properties. We highlight recent advances in plant lipid translational biology and discuss untapped areas of research that might expand the application of plant lipids.
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Affiliation(s)
- Patrick J Horn
- Michigan State University-U.S. Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
| | - Christoph Benning
- Michigan State University-U.S. Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA. Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824, USA.
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Guo X, Fan C, Chen Y, Wang J, Yin W, Wang RRC, Hu Z. Identification and characterization of an efficient acyl-CoA: diacylglycerol acyltransferase 1 (DGAT1) gene from the microalga Chlorella ellipsoidea. BMC PLANT BIOLOGY 2017; 17:48. [PMID: 28222675 PMCID: PMC5319178 DOI: 10.1186/s12870-017-0995-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Accepted: 02/02/2017] [Indexed: 05/06/2023]
Abstract
BACKGROUND Oil in the form of triacylglycerols (TAGs) is quantitatively the most important storage form of energy for eukaryotic cells. Diacylglycerol acyltransferase (DGAT) is considered the rate-limiting enzyme for TAG accumulation. Chlorella, a unicellular eukaryotic green alga, has attracted much attention as a potential feedstock for renewable energy production. However, the function of DGAT1 in Chlorella has not been reported. RESULTS A full-length cDNA encoding a putative diacylglycerol acyltransferase 1 (DGAT1, EC 2.3.1.20) was obtained from Chlorella ellipsoidea. The 2,142 bp open reading frame of this cDNA, designated CeDGAT1, encodes a protein of 713 amino acids showing no more than 40% identity with DGAT1s of higher plants. Transcript analysis showed that the expression level of CeDGAT1 markedly increased under nitrogen starvation, which led to significant triacylglycerol (TAG) accumulation. CeDGAT1 activity was confirmed in the yeast quadruple mutant strain H1246 by restoring its ability to produce TAG. Upon expression of CeDGAT1, the total fatty acid content in wild-type yeast (INVSc1) increased by 142%, significantly higher than that transformed with DGAT1s from higher plants, including even the oil crop soybean. The over-expression of CeDGAT1 under the NOS promoter in wild-type Arabidopsis thaliana and Brassica napus var. Westar significantly increased the oil content by 8-37% and 12-18% and the average 1,000-seed weight by 9-15% and 6-29%, respectively, but did not alter the fatty acid composition of the seed oil. The net increase in the 1,000-seed total lipid content was up to 25-50% in both transgenic Arabidopsis and B. napus. CONCLUSIONS We identified a gene encoding DGAT1 in C. ellipsoidea and confirmed that it plays an important role in TAG accumulation. This is the first functional analysis of DGAT1 in Chlorella. This information is important for understanding lipid synthesis and accumulation in Chlorella and for genetic engineering to enhance oil production in microalgae and oil plants.
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Affiliation(s)
- Xuejie Guo
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Chengming Fan
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Yuhong Chen
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Jingqiao Wang
- Institute of Economical Crops, Yunnan Agricultural Academy, Kunming, 65023 China
| | - Weibo Yin
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Richard R. C. Wang
- United States Department of Agriculture, Agricultural Research Service, Forage and Range Research Laboratory, Utah State University, Logan, UT 84322-6300 USA
| | - Zanmin Hu
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
- Present address: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing, 100101 China
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Motwalli O, Essack M, Jankovic BR, Ji B, Liu X, Ansari HR, Hoehndorf R, Gao X, Arold ST, Mineta K, Archer JAC, Gojobori T, Mijakovic I, Bajic VB. In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria. BMC Genomics 2017; 18:33. [PMID: 28056772 PMCID: PMC5217662 DOI: 10.1186/s12864-016-3389-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 12/07/2016] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. RESULTS Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis. CONCLUSION To our knowledge FFASC is the first in silico method to screen cyanobacteria proteomes for their potential to produce and excrete FFA, as well as the first attempt to parameterize the criteria derived from genetic characteristics that are favorable/non-favorable for this purpose. Thus, FFASC helps focus experimental evaluation only on the most promising cyanobacteria.
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Affiliation(s)
- Olaa Motwalli
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Magbubah Essack
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Boris R. Jankovic
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Boyang Ji
- Division of Systems & Synthetic Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 41296 Gothenburg, Sweden
| | - Xinyao Liu
- SABIC Corporate Research and Development (CRD), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Hifzur Rahman Ansari
- Pathogen Genomics Laboratory, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Robert Hoehndorf
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Xin Gao
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Stefan T. Arold
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Katsuhiko Mineta
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - John A. C. Archer
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Takashi Gojobori
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
| | - Ivan Mijakovic
- Division of Systems & Synthetic Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 41296 Gothenburg, Sweden
| | - Vladimir B. Bajic
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900 Kingdom of Saudi Arabia
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Zienkiewicz K, Zienkiewicz A, Poliner E, Du ZY, Vollheyde K, Herrfurth C, Marmon S, Farré EM, Feussner I, Benning C. Nannochloropsis, a rich source of diacylglycerol acyltransferases for engineering of triacylglycerol content in different hosts. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:8. [PMID: 28070221 PMCID: PMC5210179 DOI: 10.1186/s13068-016-0686-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 12/10/2016] [Indexed: 05/03/2023]
Abstract
BACKGROUND Photosynthetic microalgae are considered a viable and sustainable resource for biofuel feedstocks, because they can produce higher biomass per land area than plants and can be grown on non-arable land. Among many microalgae considered for biofuel production, Nannochloropsis oceanica (CCMP1779) is particularly promising, because following nutrient deprivation it produces very high amounts of triacylglycerols (TAG). The committed step in TAG synthesis is catalyzed by acyl-CoA:diacylglycerol acyltransferase (DGAT). Remarkably, a total of 13 putative DGAT-encoding genes have been previously identified in CCMP1779 but most have not yet been studied in detail. RESULTS Based on their expression profile, six out of 12 type-2 DGAT-encoding genes (NoDGTT1-NoDGTT6) were chosen for their possible role in TAG biosynthesis and the respective cDNAs were expressed in a TAG synthesis-deficient mutant of yeast. Yeast expressing NoDGTT5 accumulated TAG to the highest level. Over-expression of NoDGTT5 in CCMP1779 grown in N-replete medium resulted in levels of TAG normally observed only after N deprivation. Reduced growth rates accompanied NoDGTT5 over-expression in CCMP1779. Constitutive expression of NoDGTT5 in Arabidopsis thaliana was accompanied by increased TAG content in seeds and leaves. A broad substrate specificity for NoDGTT5 was revealed, with preference for unsaturated acyl groups. Furthermore, NoDGTT5 was able to successfully rescue the Arabidopsis tag1-1 mutant by restoring the TAG content in seeds. CONCLUSIONS Taken together, our results identified NoDGTT5 as the most promising gene for the engineering of TAG synthesis in multiple hosts among the 13 DGAT-encoding genes of N. oceanica CCMP1779. Consequently, this study demonstrates the potential of NoDGTT5 as a tool for enhancing the energy density in biomass by increasing TAG content in transgenic crops used for biofuel production.
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Affiliation(s)
- Krzysztof Zienkiewicz
- Michigan State University-US Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
| | - Agnieszka Zienkiewicz
- Michigan State University-US Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
- Great Lakes Bioenergy Center, Michigan State University, East Lansing, MI 48824 USA
| | - Eric Poliner
- Cell and Molecular Biology Program, Michigan State University, East Lansing, MI 48824 USA
| | - Zhi-Yan Du
- Michigan State University-US Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
| | - Katharina Vollheyde
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
| | - Cornelia Herrfurth
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
| | - Sofia Marmon
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
- Dept. of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Eva M. Farré
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
| | - Ivo Feussner
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, 37073 Göttingen, Germany
- Department of Plant Biochemistry, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University, 37073 Göttingen, Germany
- Department of Plant Biochemistry, International Center for Advanced Studies of Energy Conversion (ICASEC), Georg-August-University, 37073 Göttingen, Germany
| | - Christoph Benning
- Michigan State University-US Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 USA
- Great Lakes Bioenergy Center, Michigan State University, East Lansing, MI 48824 USA
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824 USA
- Department Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824 USA
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Current advances in molecular, biochemical, and computational modeling analysis of microalgal triacylglycerol biosynthesis. Biotechnol Adv 2016; 34:1046-1063. [DOI: 10.1016/j.biotechadv.2016.06.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 06/08/2016] [Accepted: 06/12/2016] [Indexed: 12/12/2022]
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Li DW, Cen SY, Liu YH, Balamurugan S, Zheng XY, Alimujiang A, Yang WD, Liu JS, Li HY. A type 2 diacylglycerol acyltransferase accelerates the triacylglycerol biosynthesis in heterokont oleaginous microalga Nannochloropsis oceanica. J Biotechnol 2016; 229:65-71. [DOI: 10.1016/j.jbiotec.2016.05.005] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 05/02/2016] [Accepted: 05/03/2016] [Indexed: 11/15/2022]
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40
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Huang W, Ye J, Zhang J, Lin Y, He M, Huang J. Transcriptome analysis of Chlorella zofingiensis to identify genes and their expressions involved in astaxanthin and triacylglycerol biosynthesis. ALGAL RES 2016. [DOI: 10.1016/j.algal.2016.05.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Chen B, Wang J, Zhang G, Liu J, Manan S, Hu H, Zhao J. Two types of soybean diacylglycerol acyltransferases are differentially involved in triacylglycerol biosynthesis and response to environmental stresses and hormones. Sci Rep 2016; 6:28541. [PMID: 27345221 PMCID: PMC4921965 DOI: 10.1038/srep28541] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 06/06/2016] [Indexed: 12/15/2022] Open
Abstract
Diacylglycerol acyltransferases (DGATs) play a key role in plant triacylglycerol (TAG) biosynthesis. Two type 1 and 2 DGATs from soybean were characterized for their functions in TAG biosynthesis and physiological roles. GmDGAT1A is highly expressed in seeds while GmDGAT2D is mainly expressed in flower tissues. They showed different expression patterns in response to biotic and abiotic stresses. GmDGAT2D was up-regulated by cold and heat stress and ABA signaling, and repressed by insect biting and jasmonate, whereas GmDGAT1A show fewer responses. Both GmDGAT1A and GmDGAT2D were localized to the endoplasmic reticulum and complemented the TAG deficiency of a yeast mutant H1246. GmDGAT2D-transgenic hairy roots synthesized more 18:2- or 18:1-TAG, whereas GmDGAT1A prefers to use 18:3-acyl CoA for TAG synthesis. Overexpression of both GmDGATs in Arabidopsis seeds enhanced the TAG production; GmDGAT2D promoted 18:2-TAG in wild-type but enhanced 18:1-TAG production in rod1 mutant seeds, with a decreased 18:3-TAG. However, GmDGAT1A enhanced 18:3-TAG and reduced 20:1-TAG contents. The different substrate preferences of two DGATs may confer diverse fatty acid profiles in soybean oils. While GmDGAT1A may play a role in usual seed TAG production and GmDGAT2D is also involved in usual TAG biosynthesis in other tissues in responses to environmental and hormonal cues.
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Affiliation(s)
- BeiBei Chen
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Junejie Wang
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Gaoyang Zhang
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jiaqi Liu
- College of Agronomy, Jilin Agricultural University, Changchun, 130047, China
| | - Sehrish Manan
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Honghong Hu
- National Key Laboratory of Crop Genetic Improvement, College of Life Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jian Zhao
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, 430070, China
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Xu C, Shanklin J. Triacylglycerol Metabolism, Function, and Accumulation in Plant Vegetative Tissues. ANNUAL REVIEW OF PLANT BIOLOGY 2016; 67:179-206. [PMID: 26845499 DOI: 10.1146/annurev-arplant-043015-111641] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Oils in the form of triacylglycerols are the most abundant energy-dense storage compounds in eukaryotes, and their metabolism plays a key role in cellular energy balance, lipid homeostasis, growth, and maintenance. Plants accumulate oils primarily in seeds and fruits. Plant oils are used for food and feed and, increasingly, as feedstocks for biodiesel and industrial chemicals. Although plant vegetative tissues do not accumulate significant levels of triacylglycerols, they possess a high capacity for their synthesis, storage, and metabolism. The development of plants that accumulate oil in vegetative tissues presents an opportunity for expanded production of triacylglycerols as a renewable and sustainable bioenergy source. Here, we review recent progress in the understanding of triacylglycerol synthesis, turnover, storage, and function in leaves and discuss emerging genetic engineering strategies targeted at enhancing triacylglycerol accumulation in biomass crops. Such plants could potentially be modified to produce oleochemical feedstocks or nutraceuticals.
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Affiliation(s)
- Changcheng Xu
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973; ,
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973; ,
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Hung CH, Kanehara K, Nakamura Y. Isolation and characterization of a mutant defective in triacylglycerol accumulation in nitrogen-starved Chlamydomonas reinhardtii. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1282-1293. [PMID: 27060488 DOI: 10.1016/j.bbalip.2016.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 03/31/2016] [Accepted: 04/01/2016] [Indexed: 11/30/2022]
Abstract
Triacylglycerol (TAG), a major source of biodiesel production, accumulates in nitrogen-starved Chlamydomonas reinhardtii. However, the metabolic pathway of starch-to-TAG conversion remains elusive because an enzyme that affects the starch degradation is unknown. Here, we isolated a new class of mutant bgal1, which expressed an overaccumulation of starch granules and defective photosynthetic growth. The bgal1 was a null mutant of a previously uncharacterized β-galactosidase-like gene (Cre02.g119700), which decreased total β-galactosidase activity 40% of the wild type. Upon nitrogen starvation, the bgal1 mutant showed decreased TAG accumulation mainly due to the reduced flux of de novo TAG biosynthesis evidenced by increased unsaturation of fatty acid composition in TAG and reduced TAG accumulation by additional supplementation of acetate to the culture media. Metabolomic analysis of the bgal1 mutant showed significantly reduced levels of metabolites following the hydrolysis of starch and substrates for TAG accumulation, whereas metabolites in TCA cycle were unaffected. Upon nitrogen starvation, while levels of glucose 6-phosphate, fructose 6-phosphate and acetyl-CoA remained lower, most of the other metabolites in glycolysis were increased but those in the TCA cycle were decreased, supporting TAG accumulation. We suggest that BGAL1 may be involved in the degradation of starch, which affects TAG accumulation in nitrogen-starved C. reinhardtii. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Affiliation(s)
- Chun-Hsien Hung
- Institute of Plant and Microbial Biology, Academia Sinica, 128 sec.2 Academia Rd. Nankang, Taipei 11529, Taiwan.
| | - Kazue Kanehara
- Institute of Plant and Microbial Biology, Academia Sinica, 128 sec.2 Academia Rd. Nankang, Taipei 11529, Taiwan.
| | - Yuki Nakamura
- Institute of Plant and Microbial Biology, Academia Sinica, 128 sec.2 Academia Rd. Nankang, Taipei 11529, Taiwan; PRESTO, Japan Science and Technology Agency, A-1-8 Honcho Kawaguchi, Saitama, Japan.
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Liu J, Han D, Yoon K, Hu Q, Li Y. Characterization of type 2 diacylglycerol acyltransferases in Chlamydomonas reinhardtii reveals their distinct substrate specificities and functions in triacylglycerol biosynthesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 86:3-19. [PMID: 26919811 DOI: 10.1111/tpj.13143] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/04/2016] [Accepted: 02/08/2016] [Indexed: 05/03/2023]
Abstract
Diacylglycerol acyltransferases (DGATs) catalyze a rate-limiting step of triacylglycerol (TAG) biosynthesis in higher plants and yeast. The genome of the green alga Chlamydomonas reinhardtii has multiple genes encoding type 2 DGATs (DGTTs). Here we present detailed functional and biochemical analyses of Chlamydomonas DGTTs. In vitro enzyme analysis using a radiolabel-free assay revealed distinct substrate specificities of three DGTTs: CrDGTT1 preferred polyunsaturated acyl CoAs, CrDGTT2 preferred monounsaturated acyl CoAs, and CrDGTT3 preferred C16 CoAs. When diacylglycerol was used as the substrate, CrDGTT1 preferred C16 over C18 in the sn-2 position of the glycerol backbone, but CrDGTT2 and CrDGTT3 preferred C18 over C16. In vivo knockdown of CrDGTT1, CrDGTT2 or CrDGTT3 resulted in 20-35% decreases in TAG content and a reduction of specific TAG fatty acids, in agreement with the findings of the in vitro assay and fatty acid feeding test. These results demonstrate that CrDGTT1, CrDGTT2 and CrDGTT3 possess distinct specificities toward acyl CoAs and diacylglycerols, and may work in concert spatially and temporally to synthesize diverse TAG species in C. reinhardtii. CrDGTT1 was shown to prefer prokaryotic lipid substrates and probably resides in both the endoplasmic reticulum and chloroplast envelope, indicating its role in prokaryotic and eukaryotic TAG biosynthesis. Based on these findings, we propose a working model for the role of CrDGTT1 in TAG biosynthesis. This work provides insight into TAG biosynthesis in C. reinhardtii, and paves the way for engineering microalgae for production of biofuels and high-value bioproducts.
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Affiliation(s)
- Jin Liu
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland Baltimore County, Baltimore, MD, 21202, USA
- Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing, 100871, China
| | - Danxiang Han
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Kangsup Yoon
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Qiang Hu
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Yantao Li
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland Baltimore County, Baltimore, MD, 21202, USA
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Allen DK. Assessing compartmentalized flux in lipid metabolism with isotopes. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1226-1242. [PMID: 27003250 DOI: 10.1016/j.bbalip.2016.03.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Revised: 03/13/2016] [Accepted: 03/14/2016] [Indexed: 12/28/2022]
Abstract
Metabolism in plants takes place across multiple cell types and within distinct organelles. The distributions equate to spatial heterogeneity; though the limited means to experimentally assess metabolism frequently involve homogenizing tissues and mixing metabolites from different locations. Most current isotope investigations of metabolism therefore lack the ability to resolve spatially distinct events. Recognition of this limitation has resulted in inspired efforts to advance metabolic flux analysis and isotopic labeling techniques. Though a number of these efforts have been applied to studies in central metabolism; recent advances in instrumentation and techniques present an untapped opportunity to make similar progress in lipid metabolism where the use of stable isotopes has been more limited. These efforts will benefit from sophisticated radiolabeling reports that continue to enrich our knowledge on lipid biosynthetic pathways and provide some direction for stable isotope experimental design and extension of MFA. Evidence for this assertion is presented through the review of several elegant stable isotope studies and by taking stock of what has been learned from radioisotope investigations when spatial aspects of metabolism were considered. The studies emphasize that glycerolipid production occurs across several locations with assembly of lipids in the ER or plastid, fatty acid biosynthesis occurring in the plastid, and the generation of acetyl-CoA and glycerol-3-phosphate taking place at multiple sites. Considering metabolism in this context underscores the cellular and subcellular organization that is important to enhanced production of glycerolipids in plants. An attempt is made to unify salient features from a number of reports into a diagrammatic model of lipid metabolism and propose where stable isotope labeling experiments and further flux analysis may help address questions in the field. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Affiliation(s)
- Doug K Allen
- United States Department of Agriculture, Agricultural Research Service, 975 North Warson Road, St. Louis, MO 63132, United States; Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, United States.
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Hung CH, Kanehara K, Nakamura Y. In vivo Reconstitution of Algal Triacylglycerol Production in Saccharomyces cerevisiae. Front Microbiol 2016; 7:70. [PMID: 26913021 PMCID: PMC4753380 DOI: 10.3389/fmicb.2016.00070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/15/2016] [Indexed: 11/16/2022] Open
Abstract
The current fascination with algal biofuel production stems from a high lipid biosynthetic capacity and little conflict with land plant cultivation. However, the mechanisms which enable algae to accumulate massive oil remain elusive. An enzyme for triacylglycerol (TAG) biosynthesis in Chlamydomonas reinhardtii, CrDGTT2, can produce a large amount of TAG when expressed in yeast or higher plants, suggesting a unique ability of CrDGTT2 to enhance oil production in a heterologous system. Here, we performed metabolic engineering in Saccharomyces cerevisiae by taking advantage of CrDGTT2. We suppressed membrane phospholipid biosynthesis at the log phase by mutating OPI3, enhanced TAG biosynthetic pathway at the stationary phase by overexpressing PAH1 and CrDGTT2, and suppressed TAG hydrolysis on growth resumption from the stationary phase by knocking out DGK1. The resulting engineered yeast cells accumulated about 70-fold of TAG compared with wild type cells. Moreover, TAG production was sustainable. Our results demonstrated the enhanced and sustainable TAG production in the yeast synthetic platform.
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Affiliation(s)
- Chun-Hsien Hung
- Institute of Plant and Microbial Biology, Academia Sinica Taipei, Taiwan
| | - Kazue Kanehara
- Institute of Plant and Microbial Biology, Academia Sinica Taipei, Taiwan
| | - Yuki Nakamura
- Institute of Plant and Microbial Biology, Academia SinicaTaipei, Taiwan; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology AgencySaitama, Japan
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Stress-induced neutral lipid biosynthesis in microalgae - Molecular, cellular and physiological insights. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1269-1281. [PMID: 26883557 DOI: 10.1016/j.bbalip.2016.02.008] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/04/2016] [Accepted: 02/07/2016] [Indexed: 01/01/2023]
Abstract
Photosynthetic microalgae have promise as biofuel feedstock. Under certain conditions, they produce substantial amounts of neutral lipids, mainly in the form of triacylglycerols (TAGs), which can be converted to fuels. Much of our current knowledge on the genetic and molecular basis of algal neutral lipid metabolism derives mainly from studies of plants, i.e. seed tissues, and to a lesser extent from direct studies of algal lipid metabolism. Thus, the knowledge of TAG synthesis and the cellular trafficking of TAG precursors in algal cells is to a large extent based on genome predictions, and most aspects of TAG metabolism have yet to be experimentally verified. The biofuel prospects of microalgae have raised the interest in mechanistic studies of algal TAG biosynthesis in recent years and resulted in an increasing number of publications on lipid metabolism in microalgae. In this review we summarize the current findings on genetic, molecular and physiological studies of TAG accumulation in microalgae. Special emphasis is on the functional analysis of key genes involved in TAG synthesis, molecular mechanisms of regulation of TAG biosynthesis, as well as on possible mechanisms of lipid droplet formation in microalgal cells. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Li X, Zhang R, Patena W, Gang SS, Blum SR, Ivanova N, Yue R, Robertson JM, Lefebvre PA, Fitz-Gibbon ST, Grossman AR, Jonikas MC. An Indexed, Mapped Mutant Library Enables Reverse Genetics Studies of Biological Processes in Chlamydomonas reinhardtii. THE PLANT CELL 2016; 28:367-87. [PMID: 26764374 PMCID: PMC4790863 DOI: 10.1105/tpc.15.00465] [Citation(s) in RCA: 232] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 11/30/2015] [Accepted: 01/11/2016] [Indexed: 05/18/2023]
Abstract
The green alga Chlamydomonas reinhardtii is a leading unicellular model for dissecting biological processes in photosynthetic eukaryotes. However, its usefulness has been limited by difficulties in obtaining mutants in specific genes of interest. To allow generation of large numbers of mapped mutants, we developed high-throughput methods that (1) enable easy maintenance of tens of thousands of Chlamydomonas strains by propagation on agar media and by cryogenic storage, (2) identify mutagenic insertion sites and physical coordinates in these collections, and (3) validate the insertion sites in pools of mutants by obtaining >500 bp of flanking genomic sequences. We used these approaches to construct a stably maintained library of 1935 mapped mutants, representing disruptions in 1562 genes. We further characterized randomly selected mutants and found that 33 out of 44 insertion sites (75%) could be confirmed by PCR, and 17 out of 23 mutants (74%) contained a single insertion. To demonstrate the power of this library for elucidating biological processes, we analyzed the lipid content of mutants disrupted in genes encoding proteins of the algal lipid droplet proteome. This study revealed a central role of the long-chain acyl-CoA synthetase LCS2 in the production of triacylglycerol from de novo-synthesized fatty acids.
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Affiliation(s)
- Xiaobo Li
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Ru Zhang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Weronika Patena
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Spencer S Gang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Sean R Blum
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Nina Ivanova
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Rebecca Yue
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Jacob M Robertson
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Paul A Lefebvre
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108
| | - Sorel T Fitz-Gibbon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
| | - Martin C Jonikas
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305
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Havko NE, Major IT, Jewell JB, Attaran E, Browse J, Howe GA. Control of Carbon Assimilation and Partitioning by Jasmonate: An Accounting of Growth-Defense Tradeoffs. PLANTS 2016; 5:plants5010007. [PMID: 27135227 PMCID: PMC4844420 DOI: 10.3390/plants5010007] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 01/10/2016] [Accepted: 01/12/2016] [Indexed: 12/02/2022]
Abstract
Plant growth is often constrained by the limited availability of resources in the microenvironment. Despite the continuous threat of attack from insect herbivores and pathogens, investment in defense represents a lost opportunity to expand photosynthetic capacity in leaves and absorption of nutrients and water by roots. To mitigate the metabolic expenditure on defense, plants have evolved inducible defense strategies. The plant hormone jasmonate (JA) is a key regulator of many inducible defenses. Synthesis of JA in response to perceived danger leads to the deployment of a variety of defensive structures and compounds, along with a potent inhibition of growth. Genetic studies have established an important role for JA in mediating tradeoffs between growth and defense. However, several gaps remain in understanding of how JA signaling inhibits growth, either through direct transcriptional control of JA-response genes or crosstalk with other signaling pathways. Here, we highlight recent progress in uncovering the role of JA in controlling growth-defense balance and its relationship to resource acquisition and allocation. We also discuss tradeoffs in the context of the ability of JA to promote increased leaf mass per area (LMA), which is a key indicator of leaf construction costs and leaf life span.
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Affiliation(s)
- Nathan E Havko
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USA.
| | - Ian T Major
- Department of Energy-Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
| | - Jeremy B Jewell
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USA.
| | - Elham Attaran
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USA.
| | - John Browse
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USA.
| | - Gregg A Howe
- Department of Energy-Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
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Xu C, Andre C, Fan J, Shanklin J. Cellular Organization of Triacylglycerol Biosynthesis in Microalgae. Subcell Biochem 2016; 86:207-221. [PMID: 27023237 DOI: 10.1007/978-3-319-25979-6_9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Eukaryotic cells are characterized by compartmentalization and specialization of metabolism within membrane-bound organelles. Nevertheless, many fundamental processes extend across multiple subcellular compartments. Here, we describe and assess the pathways and cellular organization of triacylglycerol biosynthesis in microalgae. In particular, we emphases the dynamic interplay among the endoplasmic reticulum, lipid droplets and chloroplasts in acyl remodeling and triacylglycerol accumulation under nitrogen starvation in the model alga Chlamydomonas reinhardtii.
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Affiliation(s)
- Changcheng Xu
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA.
| | - Carl Andre
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Jilian Fan
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
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