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 ma...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 mecha- nistic 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^D 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.展开更多
The composition of polyun saturated fatty acids (PUFAs) in triacylglycerols (TAGs) is key to health ben efits and for oil applications, yet the underlying genetic mechanism remains poorly understood. In this study, by...The composition of polyun saturated fatty acids (PUFAs) in triacylglycerols (TAGs) is key to health ben efits and for oil applications, yet the underlying genetic mechanism remains poorly understood. In this study, by in si Iico, ex vivo, and in vivo profili ng 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), respective!y. 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.展开更多
Objective To identify the active compounds from the barks of Betula platyphylla for inhibitory on diacylglycerol acyltransferase(DGAT1).Methods Bioassay-guided fractionation resulted in the isolation of DGAT1 inhibi...Objective To identify the active compounds from the barks of Betula platyphylla for inhibitory on diacylglycerol acyltransferase(DGAT1).Methods Bioassay-guided fractionation resulted in the isolation of DGAT1 inhibitory activity of lupane triterpenes.Results Ten compounds were identified as lupenone(1),lupeol(2),betulinic acid(3),betulinaldehyde(4),betulin(5),3-deoxybetulonic acid(6),glochidonol(7),lup-20/29-ene-1β/3β-diol(8),3α-hydroxy-lup-20(29)-en-23,28-dioic acid(9),and 3α,11α-dihydroxy-23-oxo-lup-20(29)-en-28-oic acid(10).Compounds 3-6,9,and 10 inhibited DGAT1 with IC50 values ranging from(11.2±0.3)to(38.6±1.2)μmol/L.Conclusion Compounds 6,9,and 10 are first isolated from the barks of B.platyphylla.,and compounds 3-6,9,and 10 from the barks of B.platyphylla are responsible for the inhibition on DGAT1.展开更多
In Arabidopsis, three lipase-like regulators, SAG101, EDS1, and PAD4, act downstream of resistance protein-associated defense signaling. Although the roles of SAG101, EDS1, and PAD4 in biotic stress have been extensiv...In Arabidopsis, three lipase-like regulators, SAG101, EDS1, and PAD4, act downstream of resistance protein-associated defense signaling. Although the roles of SAG101, EDS1, and PAD4 in biotic stress have been extensively studied, little is known about their functions in plant responses to abiotic stresses. Here, we show that SAG101, EDS1, and PAD4 are involved in the regulation of freezing tolerance in Arabidopsis. With or without cold acclimation, the sag101, edsl, and pad4 single mutants, as well as their double mutants, exhibited similarly enhanced tolerance to freezing temperatures. Upon cold exposure, the sag101, edsl, and pad4 mutants showed increased transcript levels of C-REPEAT/DRE BINDING FACTORs and their regulons compared with the wild type. Moreover, freezing-induced cell death and accumulation of hydrogen peroxide were ameliorated in sag101, edsl, and pad4 mutants. The sag101, edsl, and pad4 mutants had much lower salicylic acid (SA) and diacylglycerol (DAG) contents than the wild type, and exogenous application of SA and DAG compromised the freezing tolerance of the mutants. Furthermore, SA suppressed the cold-induced expression of DGATs and DGKs in the wild-type leaves. These findings indicate that SAG101, EDS1, and PAD4 are involved in the freezing response in Arabidopsis, at least in part, by modulating the homeostasis of SA and DAG.展开更多
文摘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 mecha- nistic 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^D 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.
基金the Natural Science Foundation of China (31600059, 31425002, and 31741005), the Natural Science Foundation of Shandong, China (ZR2015CQ003 and ZR201709180185)the Biological Carbon Sequestration Program (ZDRW-ZS-2016-3) from the Chinese Academy of Sciencesthe Chinese Key R&D Plan for Synthetic Biology Project.
文摘The composition of polyun saturated fatty acids (PUFAs) in triacylglycerols (TAGs) is key to health ben efits and for oil applications, yet the underlying genetic mechanism remains poorly understood. In this study, by in si Iico, ex vivo, and in vivo profili ng 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), respective!y. 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.
基金Science and Technology Development Program of Jilin Province(201205099)
文摘Objective To identify the active compounds from the barks of Betula platyphylla for inhibitory on diacylglycerol acyltransferase(DGAT1).Methods Bioassay-guided fractionation resulted in the isolation of DGAT1 inhibitory activity of lupane triterpenes.Results Ten compounds were identified as lupenone(1),lupeol(2),betulinic acid(3),betulinaldehyde(4),betulin(5),3-deoxybetulonic acid(6),glochidonol(7),lup-20/29-ene-1β/3β-diol(8),3α-hydroxy-lup-20(29)-en-23,28-dioic acid(9),and 3α,11α-dihydroxy-23-oxo-lup-20(29)-en-28-oic acid(10).Compounds 3-6,9,and 10 inhibited DGAT1 with IC50 values ranging from(11.2±0.3)to(38.6±1.2)μmol/L.Conclusion Compounds 6,9,and 10 are first isolated from the barks of B.platyphylla.,and compounds 3-6,9,and 10 from the barks of B.platyphylla are responsible for the inhibition on DGAT1.
文摘In Arabidopsis, three lipase-like regulators, SAG101, EDS1, and PAD4, act downstream of resistance protein-associated defense signaling. Although the roles of SAG101, EDS1, and PAD4 in biotic stress have been extensively studied, little is known about their functions in plant responses to abiotic stresses. Here, we show that SAG101, EDS1, and PAD4 are involved in the regulation of freezing tolerance in Arabidopsis. With or without cold acclimation, the sag101, edsl, and pad4 single mutants, as well as their double mutants, exhibited similarly enhanced tolerance to freezing temperatures. Upon cold exposure, the sag101, edsl, and pad4 mutants showed increased transcript levels of C-REPEAT/DRE BINDING FACTORs and their regulons compared with the wild type. Moreover, freezing-induced cell death and accumulation of hydrogen peroxide were ameliorated in sag101, edsl, and pad4 mutants. The sag101, edsl, and pad4 mutants had much lower salicylic acid (SA) and diacylglycerol (DAG) contents than the wild type, and exogenous application of SA and DAG compromised the freezing tolerance of the mutants. Furthermore, SA suppressed the cold-induced expression of DGATs and DGKs in the wild-type leaves. These findings indicate that SAG101, EDS1, and PAD4 are involved in the freezing response in Arabidopsis, at least in part, by modulating the homeostasis of SA and DAG.