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1.
Plants contain a large diversity of sphingolipid structures, arising in part from C4 hydroxylation and Δ4 and Δ8 desaturation of the component long-chain bases (LCBs). Typically, 85-90% of sphingolipid LCBs in Arabidopsis leaves contain a cis or transΔ8 double bond produced by sphingoid LCB Δ8 desaturase (SLD). To understand the metabolic and physiological significance of Δ8 unsaturation, studies were performed using mutants of the Arabidopsis SLD genes AtSLD1 and AtSLD2. Our studies revealed that both genes are constitutively expressed, the corresponding polypeptides are ER-localized, and expression of these genes in Saccharomyces cerevisiae yields mixtures of cis/transΔ8 desaturation products, predominantly as trans isomers. Consistent in part with the higher expression of AtSLD1 in Arabidopsis plants, AtSLD1 T-DNA mutants showed large reductions in Δ8 unsaturated LCBs in all organs examined, whereas AtSLD2 mutants showed little change in LCB unsaturation. Double mutants of AtSLD1 and AtSLD2 showed no detectable LCB Δ8 unsaturation. Comprehensive analysis of sphingolipids in rosettes of these mutants revealed a 50% reduction in glucosylceramide levels and a corresponding increase in glycosylinositolphosphoceramides that were restored by complementation with a wild-type copy of AtSLD1. Double sld1 sld2 mutants lacked apparent growth phenotypes under optimal conditions, but displayed altered responses to certain stresses, including prolonged exposure to low temperatures. These results are consistent with a role for LCB Δ8 unsaturation in selective channeling of ceramides for the synthesis of complex sphingolipids and the physiological performance of Arabidopsis. 相似文献
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Laxman Yetukuri Sanni S?derlund Artturi Koivuniemi Tuulikki Sepp?nen-Laakso Perttu S. Niemel? Marja Hyv?nen Marja-Riitta Taskinen Ilpo Vattulainen Matti Jauhiainen Matej Ore?i? 《Journal of lipid research》2010,51(8):2341-2351
A low level of high density lipoprotein cholesterol (HDL-C) is a powerful risk factor for cardiovascular disease. However, despite the reported key role of apolipo-proteins, specifically, apoA-I, in HDL metabolism, lipid molecular composition of HDL particles in subjects with high and low HDL-C levels is currently unknown. Here lipidomics was used to study HDL derived from well-characterized high and low HDL-C subjects. Low HDL-C subjects had elevated triacylglycerols and diminished lysophosphatidylcholines and sphingomyelins. Using information about the lipid composition of HDL particles in these two groups, we reconstituted HDL particles in silico by performing large-scale molecular dynamics simulations. In addition to confirming the measured change in particle size, we found that the changes in lipid composition also induced specific spatial distributions of lipids within the HDL particles, including a higher amount of triacylglycerols at the surface of HDL particles in low HDL-C subjects. Our findings have important implications for understanding HDL metabolism and function. For the first time we demonstrate the power of combining molecular profiling of lipoproteins with dynamic modeling of lipoprotein structure. 相似文献
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Imbibitional chilling injury during germination causes agricultural losses, but this can be overcome by osmopriming. It remains unknown how membranes reorganize during germination. Herein, we comparatively profiled changes of membrane lipids during imbibition under normal and chilling temperatures in chilling‐tolerant and ‐sensitive soybean seeds. We found three patterns of dynamic lipid remodelling during the three phases of germination. Pattern 1 involved a gradual increase in plastidic lipids during phases I and II, with an abrupt increase during phase III. This abrupt increase was associated with initiation of photosynthesis. Pattern 3 involved phosphatidic acid (PA) first decreasing, then increasing, and finally decreasing to a low level. Patterns 1 and 3 were interrupted in chilling‐sensitive seeds under low temperature, which lead a block in plastid biogenesis and accumulation of harmful PA, respectively. However, they were rescued and returned to their status under normal temperature after polyethylene glycol osmopriming. We specifically inhibited phospholipase D (PLD)‐mediated PA formation in chilling‐sensitive seeds of soybean, cucumber, and pea, and found their germination under low temperature was significantly improved. These results indicate that membranes undergo specific and functional reorganization of lipid composition during germination and demonstrate that PLD‐mediated PA causes imibibitional chilling injury. 相似文献
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Katharina Gaus Ben de Wet Andrej Shevchenko Kai Simons Thomas Harder 《The EMBO journal》2009,28(5):466-476
Activating stimuli for T lymphocytes are transmitted through plasma membrane domains that form at T‐cell antigen receptor (TCR) signalling foci. Here, we determined the molecular lipid composition of immunoisolated TCR activation domains. We observed that they accumulate cholesterol, sphingomyelin and saturated phosphatidylcholine species as compared with control plasma membrane fragments. This provides, for the first time, direct evidence that TCR activation domains comprise a distinct molecular lipid composition reminiscent of liquid‐ordered raft phases in model membranes. Interestingly, TCR activation domains were also enriched in plasmenyl phosphatidylethanolamine and phosphatidylserine. Modulating the T‐cell lipidome with polyunsaturated fatty acids impaired the plasma membrane condensation at TCR signalling foci and resulted in a perturbed molecular lipid composition. These results correlate the accumulation of specific molecular lipid species with the specific plasma membrane condensation at sites of TCR activation and with early TCR activation responses. 相似文献
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Understanding the adaptive changes in wheat pollen lipidome under high temperature (HT) stress is critical to improving seed set and developing HT tolerant wheat varieties. We measured 89 pollen lipid species under optimum and high day and/or night temperatures using electrospray ionization‐tandem mass spectrometry in wheat plants. The pollen lipidome had a distinct composition compared with that of leaves. Unlike in leaves, 34:3 and 36:6 species dominated the composition of extraplastidic phospholipids in pollen under optimum and HT conditions. The most HT‐responsive lipids were extraplastidic phospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol, phosphatidic acid, and phosphatidylserine. The unsaturation levels of the extraplastidic phospholipids decreased through the decreases in the levels of 18:3 and increases in the levels of 16:0, 18:0, 18:1, and 18:2 acyl chains. PC and PE were negatively correlated. Higher PC:PE at HT indicated possible PE‐to‐PC conversion, lower PE formation, or increased PE degradation, relative to PC. Correlation analysis revealed lipids experiencing coordinated metabolism under HT and confirmed the HT responsiveness of extraplastidic phospholipids. Comparison of the present results on wheat pollen with results of our previous research on wheat leaves suggests that similar lipid changes contribute to HT adaptation in both leaves and pollen, though the lipidomes have inherently distinct compositions. 相似文献
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Receptor activation leads to the dynamic remodeling of the plasma membrane. Previous work using immunoelectron microscopy showed that aggregated high-affinity receptor for immunoglobulin E (FcRI) and aggregated Thy-1, a glycerophosphoinositol (GPI)-anchored protein, have distinct membrane distributions. We now report lipidomics analysis of FcRI- and Thy-1-enriched vesicles obtained by magnetic bead isolation in the absence of detergent. Protein analyses show that FcRI domains are enriched in receptors and associated signaling molecules, whereas Thy-1 domains are devoid of FcRI subunits. Positive and negative ion electrospray mass spectrometry demonstrated that both domains retained a complex mixture of phospholipid classes and molecular species, predominantly glycerophosphocholine, glycerophosphoethanolamine (GPE), and sphingomyelin as well as glycerophosphoserine and GPI lipids. Analysis of total acyl groups showed that < 50% of fatty acids in these domains are fully saturated, inconsistent with the recruitment of aggregated receptors or GPI-anchored proteins to liquid ordered domains. However, further analysis showed that FcRI domains contain two times more sphingomyelin and a high ratio of cholesterol to total fatty acid content compared with Thy 1-enriched domains. Remarkably, plasmenyl glycerophosphoethanolamine phospholipids (plasmalogen GPE) were also 2.5-3 times more abundant in FcRI domains than in the Thy-1 microdomains, whereas most diacyl GPE molecular species were equally abundant in the two domains. 相似文献
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D.M.S.B. Dissanayaka William C. Plaxton Hans Lambers Meike Siebers Buddhi Marambe Jun Wasaki 《Plant, cell & environment》2018,41(7):1483-1496
Orthophosphate (H2PO4?, Pi) is an essential macronutrient integral to energy metabolism as well as a component of membrane lipids, nucleic acids, including ribosomal RNA, and therefore essential for protein synthesis. The Pi concentration in the solution of most soils worldwide is usually far too low for maximum growth of crops, including rice. This has prompted the massive use of inefficient, polluting, and nonrenewable phosphorus (P) fertilizers in agriculture. We urgently need alternative and more sustainable approaches to decrease agriculture's dependence on Pi fertilizers. These include manipulating crops by (a) enhancing the ability of their roots to acquire limiting Pi from the soil (i.e. increased P‐acquisition efficiency) and/or (b) increasing the total biomass/yield produced per molecule of Pi acquired from the soil (i.e. increased P‐use efficiency). Improved P‐use efficiency may be achieved by producing high‐yielding plants with lower P concentrations or by improving the remobilization of acquired P within the plant so as to maximize growth and biomass allocation to developing organs. Membrane lipid remodelling coupled with hydrolysis of RNA and smaller P‐esters in senescing organs fuels P remobilization in rice, the world's most important cereal crop. 相似文献
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Sruthi Narayanan Pamela J. Tamura Mary R. Roth P.V. Vara Prasad Ruth Welti 《Plant, cell & environment》2016,39(4):787-803
Understanding how wheat (Triticum aestivum L.) plants under high temperature (HT) regulate lipid composition is critical to developing climate‐resilient varieties. We measured 165 glycerolipids and sterol derivatives under optimum and high day and night temperatures in wheat leaves using electrospray ionization‐tandem mass spectrometry. Levels of polar lipid fatty acyl chain unsaturation were lower in both heat‐tolerant genotype Ventnor and susceptible genotype Karl 92 under HT, compared with optimum temperature. The lower unsaturation was predominantly because of lower levels of 18:3 acyl chains and higher levels of 18:1 and 16:0 acyl chains. Levels of 18:3‐containing triacylglycerols increased threefold/more under HT, consistent with their possible role in sequestering fatty acids during membrane lipid remodelling. Phospholipids containing odd‐numbered or oxidized acyl chains accumulated in leaves under HT. Sterol glycosides (SG) and 16:0‐acylated sterol glycosides (ASG) were higher under HT than optimum temperatures. Ventnor had lower amounts of phospholipids with oxidized acyl chains under HT and higher amounts of SG and 16:0‐ASG than Karl 92. Taken together, the data demonstrate that wheat leaf lipid composition is altered by HT, in which some lipids are particularly responsive to HT, and that two wheat genotypes, chosen for their differing physiological responses to HT, differ in lipid profile under HT. 相似文献
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The major components of fatty acids of the membrane Lipid in wheat (Triticum aestivum L.) are palmitie 16:0), paimitoleic (16:1), stearie (18:0), oleeic (18: 1), linoleic (18:2) linolenic acid (18:3) and a few others. Of the total fatty acids, palmitic, linoleie and linolenic acid are predominant in amount. Under the condition of high temperature and low humidity the contents of palnfitie and oloie acid in the membrane lipids increased and the linoleic and linolenie acid decreased, which resulted in high degree of saturation of membrane fatty acid. It was found that the influence of high temperature on the fatty acid compositions was stronger than that of low humidity. Two winter eultivars showed different in their resistance to high temperature and low humididty, and a difference in degree of saturation of membrane fatty acid Was also detected. The resistant eultivar possessed a higher degree of staturation of fatty acid than the sensitiveone. Similar trend was obtained from various oultivars to high temperature and low humidity. This seems to be a corelation between the resistivity of wheat cultivar to high temperature and low humidity and the degree of saturation of membrane fatty acids. 相似文献
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Identifying lipids that experience coordinated metabolism during heat stress would provide information regarding lipid dynamics under stress conditions and assist in developing heat‐tolerant wheat varieties. We hypothesized that co‐occurring lipids, which are up‐regulated or down‐regulated together through time during heat stress, represent groups that can be explained by coordinated metabolism. Wheat plants (Triticum aestivum L.) were subjected to 12 days of high day and/or night temperature stress, followed by a 4‐day recovery period. Leaves were sampled at four time points, and 165 lipids were measured by electrospray ionization‐tandem mass spectrometry. Correlation analysis of lipid levels in 160 leaf samples from each of two wheat genotypes revealed 13 groups of lipids. Lipids within each group co‐occurred through the high day and night temperature stress treatments. The lipid groups can be broadly classified as groups containing extraplastidic phospholipids, plastidic glycerolipids, oxidized glycerolipids, triacylglycerols, acylated sterol glycosides and sterol glycosides. Current knowledge of lipid metabolism suggests that the lipids in each group co‐occur because they are regulated by the same enzyme(s). The results suggest that increases in activities of desaturating, oxidizing, glycosylating and acylating enzymes lead to simultaneous changes in levels of multiple lipid species during high day and night temperature stress in wheat. 相似文献
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Influenza infection requires fusion between the virus envelope and a host cell endosomal membrane. The influenza hemagglutinin fusion peptide (FP) is essential to viral membrane fusion. It was recently proposed that FPs would fuse membranes by increasing lipid tail protrusion, a membrane fusion transition state. The details of how FPs induce lipid tail protrusion, however, remain to be elucidated. To decipher the molecular mechanism by which FPs promote lipid tail protrusion, we performed molecular dynamics simulations of the wild‐type (WT) FP, fusogenic mutant F9A, and nonfusogenic mutant W14A in model bilayers. This article presents the peptide–lipid interaction responsible for lipid tail protrusion and a related lipid perturbation, polar head intrusion, where polar heads are sunk under the membrane surface. The backbone amides from the four N‐terminal peptide residues, deeply inserted in the membrane, promoted both perturbations through H bonding with lipid phosphates. Polar head intrusion correlated with peptides N‐terminal insertion depth and activity: the N‐termini of WT and F9A were inserted deeper into the membrane than nonfusogenic W14A. Based on these results, we propose that FP‐induced polar head intrusion would complement lipid tail protrusion in catalyzing membrane fusion by reducing repulsions between juxtaposed membranes headgroups. The presented model provides a framework for further research on membrane fusion and influenza antivirals. Proteins 2014; 82:2118–2127. © 2014 Wiley Periodicals, Inc. 相似文献
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Zbigniew Kaniuga Violetta Sączyńska Ewa Miśkiewicz Maciej Garstka 《Acta Physiologiae Plantarum》1999,21(3):231-241
Changes in fatty acids of leaf polar lipids: monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG) in maize seedlings of chiling-sensitive (CS) CM 7 and Co 151 lines and chilling-tolerant (CT) S 215 and EP 1 lines upon chilling for either 4 or 6 days in the dark and after rewarming for 4 days at original growth conditions were studied. The content of free fatty acids (FFA) in control leaves as well as alterations in the proportion of major fatty acids, unsaturation ratio (UR), double bond index (DBI) and changes in the proportion of heigh-temperature melting of both phosphatidylglycerol (htm-PG) and sulfoquinovosylglycerol (htm-SQDG) after chilling and rewarming of seedlings were estimated. FFA content in intact leaves was 2–3-fold higher in the chilling susceptible CM 7 line than in the other three inbreeds studied. After chilling for 6 days the level of FFA increased only in CM 7 and S 215 lines by about 30 %. Upon rewarming seedlings chilled for 6 days the level of FFA increased about two-fold in CS Co 151 line and CT EP 1 line and decreased in CS CM 7 line. Limited accumulation of FFAs during chilling and post-chilling rewarming of maize seedlings, did not correspond to the extent of polar lipid breakdown (Kaniuga et al. 1999b) probably due to the contribution of active oxidative systems to the peroxidation of fatty acids under these conditions. During rewarming seedlings chilled for 6 days major changes were observed in decrease of 18:3 and an increase of 16:0 in all four polar lipids studied with more pronounced changes in CS than CT lines. Similarly, in CS inbreeds a decrease in UR of fatty acids in MGDG, DGDG and SQDG after post-chilling rewarming was greater than in CT lines. Proportion of htm-fraction in both PG and SQDG increased after post-chilling rewarming in all four inbreeds, however to a lesser extent in CT than CS lines. A similar pattern of changes in DBI in CS and CT maize seedlings was observed in glycolipid and combine lipid classes. More extensive degradation of polar lipids in CS than CT maize inbreeds following galactolipase action in chloroplasts (Kaniuga et al. 1998) provides FFAs for initiation of peroxidation by LOX which is manifested by decrease of UR and DBI. This sequence of reactions during chilling and post-chilling rewarming appears to be a main route of fatty acids peroxidation responsible for secondary events involved in chilling injury. In addition, the extent of these changes differentiates CS and CT inbreeds. Contribution of esterified fatty acids in thylakoid lipids to direct peroxidation, may be of minor importance. 相似文献
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M Morrisson P A Wilce B C Shanley 《Biochemical and biophysical research communications》1984,122(2):516-521
Animals chronically exposed to ethanol show changes in neural membrane lipids which may underlie the development of tolerance and physical dependence. The object of this study was to investigate changes in the fatty acid composition of neuronal phospholipids cultured in the presence of ethanol (55 or 110 mM) for periods up to 7 days. Decreases were observed in the percentage of individual and total saturated fatty acids, while the double bond index: total saturated fatty acid ratio, increased. These changes do not support the hypothesis that neural membrane lipid composition changes to counteract the fluidizing action of ethanol. 相似文献
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以木本植物巨尾桉幼苗为材料 ,研究低温胁迫对巨尾桉膜脂过氧化及保护酶的影响 ,测定了幼苗叶片的O 2(超氧阴离子 )产生速率、H2 O2 、(过氧化氢 )、MDA(丙二醛 )含量、相对电导率和SOD(超氧化物歧化酶 )、POD(过氧化物酶 )、CAT(过氧化氢酶 )、APX(抗坏血酸过氧化物酶 )活性。结果表明 :低温胁迫使叶片O 2 产生速率、H2 O2 、MDA含量和相对电导率增加 ,但抗寒锻炼植株的增幅远小于对照 ;抗寒锻炼植株的SOD、POD、CAT和APX活性均低于对照。 相似文献
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Larissa Launhardt;Johanna Uhlenberg;Hagen Stellmach;Marie Schomburg;Bettina Hause;Ingo Heilmann;Mareike Heilmann; 《The Plant journal : for cell and molecular biology》2024,117(1):242-263
The unsaturation of phospholipids influences the function of membranes. In Arabidopsis thaliana, the oleoyl Δ12-desaturase FAD2 converts oleic (18:1Δ9) to linoleic acid (18:2Δ9,12) and influences phospholipid unsaturation in different cellular membranes. Despite its importance, the precise localization of Arabidopsis FAD2 has not been unambiguously described. As FAD2 is thought to modify phospholipid-associated fatty acids at the endoplasmic reticulum (ER), from where unsaturates are distributed to other cellular sites, we hypothesized that FAD2 locates to ER subdomains enabling trafficking of lipid intermediates through the secretory pathway. Fluorescent FAD2 fusions used to test this hypothesis were first assessed for functionality by heterologous expression in yeast (Saccharomyces cerevisiae), and in planta by Arabidopsis fad2 mutant rescue upon ectopic expression from an intrinsic FAD2 promoter fragment. Light sheet fluorescence, laser scanning confocal or spinning disc microscopy of roots, leaves, or mesophyll protoplasts showed the functional fluorescence-tagged FAD2 variants in flattened donut-shaped structures of ~0.5–1 μm diameter, in a pattern not resembling mere ER association. High-resolution imaging of coexpressed organellar markers showed fluorescence-tagged FAD2 in a ring-shaped pattern surrounding ER-proximal Golgi particles, colocalizing with pre-cis-Golgi markers. This localization required the unusual C-terminal retention signal of FAD2, and deletion or substitutions in this protein region resulted in relaxed distribution and diffuse association with the ER. The distinct association of FAD2 with pre-cis-Golgi stacks in Arabidopsis root and leaf tissue is consistent with a contribution of FAD2 to membrane lipid homeostasis through the secretory pathway, as verified by an increased plasma membrane liquid phase order in the fad2 mutant. 相似文献
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Bronwyn J. Barkla Michael Melzer Thusitha W.T. Rupasinghe Ute Roessner 《Plant, cell & environment》2018,41(10):2390-2403
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吸胀冷害是干种子在吸胀阶段遭受低温造成不萌发的现象,结果可能造成农作物损失严重。虽然吸胀过程中细胞膜的修复是关键事件,而且细胞膜在响应水分和温度胁迫中扮演重要角色,但是种子吸胀过程中膜变化的过程,特别是膜流动性变化过程研究较少。本文比较了吸胀冷害耐受型（LX）和敏感型（R5）两个大豆品种在吸胀冷害过程中膜脂不饱和度（double bond index, DBI）的变化,结果发现,LX和R5在常温（25℃）吸胀时变化趋势一致,质体膜脂DBI升高,质体外膜脂中磷脂酰甘油(phosphatidylglycerol, PG)分子DBI下降。LX和R5在低温（4℃）吸胀时DBI变化有很大差异,低温吸胀仅仅延缓了耐受型LX中质体膜脂DBI的升高,但是敏感性R5质体膜脂DBI不仅没有升高反而下降。用浓度33%的聚乙二醇 (polyethylene glycol, PEG)引发没有直接引起DBI变化,但是所引起的细微而显著的变化可能为萌发做好准备。PEG引发处理后的R5在吸胀冷害后第二和第三阶段质体膜脂DBI迅速增加,这个增加模式与LX的DBI增加相似。结果表明,吸胀冷害延缓或者阻滞了质体膜脂不饱和度的升高,大豆种子的吸胀冷害抗性与质体膜脂不饱和度正相关,提高质体膜质DBI可以提高吸胀冷害抗性。 相似文献