A type-I diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga, Nannochloropsis oceanica
Abstract Background Photosynthetic oleaginous microalgae are considered promising feedstocks for biofuels. The marine microalga, Nannochloropsis oceanica, has been attracting ever-increasing interest because of its fast growth, high triacylglycerol (TAG) content, and available genome sequence and ge...
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMC
2017-07-01
|
| Series: | Biotechnology for Biofuels |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13068-017-0858-1 |
| _version_ | 1818265256945778688 |
|---|---|
| author | Hehong Wei Ying Shi Xiaonian Ma Yufang Pan Hanhua Hu Yantao Li Ming Luo Henri Gerken Jin Liu |
| author_facet | Hehong Wei Ying Shi Xiaonian Ma Yufang Pan Hanhua Hu Yantao Li Ming Luo Henri Gerken Jin Liu |
| author_sort | Hehong Wei |
| collection | DOAJ |
| description | Abstract Background Photosynthetic oleaginous microalgae are considered promising feedstocks for biofuels. The marine microalga, Nannochloropsis oceanica, has been attracting ever-increasing interest because of its fast growth, high triacylglycerol (TAG) content, and available genome sequence and genetic tools. Diacylglycerol acyltransferase (DGAT) catalyzes the last and committed step of TAG biosynthesis in the acyl-CoA-dependent pathway. Previous studies have identified 13 putative DGAT-encoding genes in the genome of N. oceanica, but the functional role of DGAT genes, especially type-I DGAT (DGAT1), remains ambiguous. Results Nannochloropsis oceanica IMET1 possesses two DGAT1 genes: NoDGAT1A and NoDGAT1B. Functional complementation demonstrated the capability of NoDGAT1A rather than NoDGAT1B to restore TAG synthesis in a TAG-deficient yeast strain. In vitro DGAT assays revealed that NoDGAT1A preferred saturated/monounsaturated acyl-CoAs and eukaryotic diacylglycerols (DAGs) for TAG synthesis, while NoDGAT1B had no detectable enzymatic activity. Assisted with green fluorescence protein (GFP) fusion, fluorescence microscopy analysis indicated the localization of NoDGAT1A in the chloroplast endoplasmic reticulum (cER) of N. oceanica. NoDGAT1A knockdown caused ~25% decline in TAG content upon nitrogen depletion, accompanied by the reduced C16:0, C18:0, and C18:1 in TAG sn-1/sn-3 positions and C18:1 in the TAG sn-2 position. NoDGAT1A overexpression, on the other hand, led to ~39% increase in TAG content upon nitrogen depletion, accompanied by the enhanced C16:0 and C18:1 in the TAG sn-1/sn-3 positions and C18:1 in the TAG sn-2 position. Interestingly, NoDGAT1A overexpression also promoted TAG accumulation (by ~2.4-fold) under nitrogen-replete conditions without compromising cell growth, and TAG yield of the overexpression line reached 0.49 g L−1 at the end of a 10-day batch culture, 47% greater than that of the control line. Conclusions Taken together, our work demonstrates the functional role of NoDGAT1A and sheds light on the underlying mechanism for the biosynthesis of various TAG species in N. oceanica. NoDGAT1A resides likely in cER and prefers to transfer C16 and C18 saturated/monounsaturated fatty acids to eukaryotic DAGs for TAG assembly. This work also provides insights into the rational genetic engineering of microalgae by manipulating rate-limiting enzymes such as DGAT to modulate TAG biosynthesis and fatty acid composition for biofuel production. |
| first_indexed | 2024-12-12T19:47:55Z |
| format | Article |
| id | doaj.art-0cfca237f709430dad83023868a56da3 |
| institution | Directory Open Access Journal |
| issn | 1754-6834 |
| language | English |
| last_indexed | 2024-12-12T19:47:55Z |
| publishDate | 2017-07-01 |
| publisher | BMC |
| record_format | Article |
| series | Biotechnology for Biofuels |
| spelling | doaj.art-0cfca237f709430dad83023868a56da32022-12-22T00:14:02ZengBMCBiotechnology for Biofuels1754-68342017-07-0110111810.1186/s13068-017-0858-1A type-I diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga, Nannochloropsis oceanicaHehong Wei0Ying Shi1Xiaonian Ma2Yufang Pan3Hanhua Hu4Yantao Li5Ming Luo6Henri Gerken7Jin Liu8Institute for Food and Bioresource Engineering, Department of Energy and Resources Engineering and BIC-ESAT, College of Engineering, Peking UniversityInstitute for Food and Bioresource Engineering, Department of Energy and Resources Engineering and BIC-ESAT, College of Engineering, Peking UniversityInstitute for Food and Bioresource Engineering, Department of Energy and Resources Engineering and BIC-ESAT, College of Engineering, Peking UniversityKey Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of SciencesKey Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of SciencesInstitute of Marine and Environmental Technology, University of Maryland Center for Environmental Science and University of Maryland Baltimore CountyGuangdong Provincial Key Laboratory of Applied Botany, Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of SciencesSchool of Sustainable Engineering and the Built Environment, Arizona State University Polytechnic campusInstitute for Food and Bioresource Engineering, Department of Energy and Resources Engineering and BIC-ESAT, College of Engineering, Peking UniversityAbstract Background Photosynthetic oleaginous microalgae are considered promising feedstocks for biofuels. The marine microalga, Nannochloropsis oceanica, has been attracting ever-increasing interest because of its fast growth, high triacylglycerol (TAG) content, and available genome sequence and genetic tools. Diacylglycerol acyltransferase (DGAT) catalyzes the last and committed step of TAG biosynthesis in the acyl-CoA-dependent pathway. Previous studies have identified 13 putative DGAT-encoding genes in the genome of N. oceanica, but the functional role of DGAT genes, especially type-I DGAT (DGAT1), remains ambiguous. Results Nannochloropsis oceanica IMET1 possesses two DGAT1 genes: NoDGAT1A and NoDGAT1B. Functional complementation demonstrated the capability of NoDGAT1A rather than NoDGAT1B to restore TAG synthesis in a TAG-deficient yeast strain. In vitro DGAT assays revealed that NoDGAT1A preferred saturated/monounsaturated acyl-CoAs and eukaryotic diacylglycerols (DAGs) for TAG synthesis, while NoDGAT1B had no detectable enzymatic activity. Assisted with green fluorescence protein (GFP) fusion, fluorescence microscopy analysis indicated the localization of NoDGAT1A in the chloroplast endoplasmic reticulum (cER) of N. oceanica. NoDGAT1A knockdown caused ~25% decline in TAG content upon nitrogen depletion, accompanied by the reduced C16:0, C18:0, and C18:1 in TAG sn-1/sn-3 positions and C18:1 in the TAG sn-2 position. NoDGAT1A overexpression, on the other hand, led to ~39% increase in TAG content upon nitrogen depletion, accompanied by the enhanced C16:0 and C18:1 in the TAG sn-1/sn-3 positions and C18:1 in the TAG sn-2 position. Interestingly, NoDGAT1A overexpression also promoted TAG accumulation (by ~2.4-fold) under nitrogen-replete conditions without compromising cell growth, and TAG yield of the overexpression line reached 0.49 g L−1 at the end of a 10-day batch culture, 47% greater than that of the control line. Conclusions Taken together, our work demonstrates the functional role of NoDGAT1A and sheds light on the underlying mechanism for the biosynthesis of various TAG species in N. oceanica. NoDGAT1A resides likely in cER and prefers to transfer C16 and C18 saturated/monounsaturated fatty acids to eukaryotic DAGs for TAG assembly. This work also provides insights into the rational genetic engineering of microalgae by manipulating rate-limiting enzymes such as DGAT to modulate TAG biosynthesis and fatty acid composition for biofuel production.http://link.springer.com/article/10.1186/s13068-017-0858-1Diacylglycerol acyltransferaseFunctional characterizationGenetic engineeringMicroalgaNannochloropsis oceanicaTriacylglycerol |
| spellingShingle | Hehong Wei Ying Shi Xiaonian Ma Yufang Pan Hanhua Hu Yantao Li Ming Luo Henri Gerken Jin Liu A type-I diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga, Nannochloropsis oceanica Biotechnology for Biofuels Diacylglycerol acyltransferase Functional characterization Genetic engineering Microalga Nannochloropsis oceanica Triacylglycerol |
| title | A type-I diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga, Nannochloropsis oceanica |
| title_full | A type-I diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga, Nannochloropsis oceanica |
| title_fullStr | A type-I diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga, Nannochloropsis oceanica |
| title_full_unstemmed | A type-I diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga, Nannochloropsis oceanica |
| title_short | A type-I diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga, Nannochloropsis oceanica |
| title_sort | type i diacylglycerol acyltransferase modulates triacylglycerol biosynthesis and fatty acid composition in the oleaginous microalga nannochloropsis oceanica |
| topic | Diacylglycerol acyltransferase Functional characterization Genetic engineering Microalga Nannochloropsis oceanica Triacylglycerol |
| url | http://link.springer.com/article/10.1186/s13068-017-0858-1 |
| work_keys_str_mv | AT hehongwei atypeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT yingshi atypeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT xiaonianma atypeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT yufangpan atypeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT hanhuahu atypeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT yantaoli atypeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT mingluo atypeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT henrigerken atypeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT jinliu atypeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT hehongwei typeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT yingshi typeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT xiaonianma typeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT yufangpan typeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT hanhuahu typeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT yantaoli typeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT mingluo typeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT henrigerken typeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica AT jinliu typeidiacylglycerolacyltransferasemodulatestriacylglycerolbiosynthesisandfattyacidcompositionintheoleaginousmicroalganannochloropsisoceanica |