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Figure S. Stability of oil bodies reconstituted from TAG, PL, and/or maize oleosins . A suspension of the reconstituted oil bodies of 1.4 ml was placed in a cuvette, and the relative turbidity (77T,,) at 600 run of the approximately lower 0.5 ml of the suspension was
Source publication
Storage triacylglycerols (TAG) in plant seeds are present in small discrete intracellular organelles called oil bodies. An oil body has a matrix of TAG, which is surrounded by phospholipids (PL) and alkaline proteins, termed oleosins. Oil bodies isolated from mature maize (Zea mays) embryos maintained their discreteness, but coalesced after treatme...
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Citations
... Oleosin protein is a structural protein that is first isolated and identified on seed oil bodies [50]. It consists of three parts, the N-terminal hydrophilic domain, the hydrophobic central structural domain and the most conservative hydrophobic hairpin zone (about 72 residues) and the C-terminal α-helical structural domain [51]. Amphiphilic oleosins are able to stabilize intracellular hydrophobic triglycerides (TAG) by inserting their hairpin regions into the oil body and exposing their Nand C-terminal hydrophilic regions [52]. ...
Background
The herbaceous peony (Paeonia lactiflora Pall.) is extensively cultivated in China due to its root being used as a traditional Chinese medicine known as ‘Radix Paeoniae Alba’. In recent years, it has been discovered that its seeds incorporate abundant unsaturated fatty acids, thereby presenting a potential new oilseed plant. Surprisingly, little is known about the full-length transcriptome sequencing of Paeonia lactiflora, limiting research into its gene function and molecular mechanisms.
Results
A total of 484,931 Reads of Inserts (ROI) sequences and 1,455,771 full-Length non-chimeric reads (FLNC) sequences were obtained for CDS prediction, TF analysis, SSR analysis and lncRNA identification. In addition, gene function annotation and gene structure analysis were performed. A total of 4905 transcripts were related to lipid metabolism biosynthesis pathway, belonging to 28 enzymes. We use these data to identify 10 oleosin (OLE) and 5 diacylglycerol acyltransferase (DGAT) gene members after de-redundancy. The analysis of physicochemical properties and secondary structure showed them similarity in gene family respectively. The phylogenetic analysis showed that the distribution of OLE and DGAT family members was roughly the same as that of Arabidopsis. Quantitative real-time polymerase chain reaction (qRT–PCR) analyses revealed expression changes in different seed development stages, and showed a trend of increasing and then decreasing.
Conclusion
In summary, these results provide new insights into the molecular mechanism of triacylglycerol (TAG) biosynthesis and storage during the seedling stage in Paeonia lactiflora. It provides theoretical references for selecting and breeding oil varieties and understanding the functions of oil storage as well as lipid synthesis related genes in Paeonia lactiflora.
... Oil bodies (OBs) are cellular organelles that reposit lipids in plant seeds [8]. They are composed of a central triglyceride core enveloped by a phospholipid monolayer with embedded OB proteins [9]. ...
Oil bodies (OBs) are naturally occurring pre-emulsified oil droplets that have broad application prospects in emulsions and gels. The main purpose of this research was to examine the impact of the OB content on the structure and functional aspects of acid-mediated soy protein isolate (SPI) gel filled with OBs. The results indicated that the peanut oil body (POBs) content significantly affected the water holding capacity of the gel. The rheological and textural analyses showed that POBs reduced the gel strength and hardness. The scanning electron and confocal laser scanning microscopy analyses revealed that POBs aggregated during gel formation and reduced the gel network density. The Fourier transform infrared spectrum (FTIR) analysis demonstrated that POBs participated in protein gels through hydrogen bonds, steric hindrance and hydrophobic interactions. Therefore, OBs served as inactive filler in the acid-mediated protein gel, replaced traditional oils and provided alternative ingredients for the development of new emulsion-filled gels.
... These TAGs form individual oil bodies on the endoplasmic reticulum membrane, which, via the acquisition of specific proteins, support the growth and expansion of oil bodies [2]. These oil bodies play a role in providing energy for seed germination and early seedling growth and development [3]. The oil body is one of the smallest organelles in plant cells, typically measuring between 0.5-2.5 µm in diameter; however, in some species, such as soybean (Glycine max), the diameter of the oil body can reach 5-7.5 µm [4]. ...
The deciduous tree hickory (Carya cathayensis) holds economic significance in China due to its high oil content, particularly in unsaturated fatty acids. Oil bodies are crucial for storing triacylglycerol (TAG), with caleosin serving as a predominant oil body protein that aids in oil body formation and stability maintenance. Our study utilized bioinformatics techniques to identify caleosin genes within Carya cathayensis, Carya illinoinensis, and Juglans regia. Three caleosin genes were discovered in the genomes of Carya cathayensis, Carya illi-noinensis, and Juglans regia. These genes encode hydrophilic proteins. Additionally, all caleosin proteins feature a single Ca2+-binding EF-hand, a conserved “proline knot” motif, and a C-terminal hydrophilic region with four potential phosphorylation sites. The caleosin proteins in Carya cathayensis consist of α-helix, β-corner, extended chain, and random curl structures. Cis-acting elements related to stress response and hormone signaling were identified in Carya cathayensis, Carya illinoinensis, and Juglans regia, with distinct cis-acting elements implicated in seed-specific regulation in Carya cathayensis. Additionally, subcellular localization analysis confirmed that CcaCLO1 and CcaCLO2 were localized within oil bodies. Transcriptome analysis and quantitative real-time polymerase chain reaction (qRT-PCR) data demonstrated a significant up-regulation of CcaCLO1 expression during the developmental stages of the Carya cathayensis embryo. Furthermore, qPCR findings indicated that caleosins from Carya cathayensis were responsive to salt stress, with a significant up-regulation of CcaCLO1 following exposure to salt stress treatment. Consequently, caleosin genes in Carya cathayensis, Carya illinoinensis, and Juglans regia share similar physicochemical characteristics and conserved motifs. Specifically, CcaCLO1 in Carya cathayensis primarily responds to embryo development and salt stress. These findings offer foundational insights for future investigations into the regulatory mechanisms of oil accumulation and response to salt stress in hickory.
... In higher plants, oleosomes are naturally emulsified oil droplets containing triacylglycerols (TAGs) in the core (94-98% w/w), covered and stabilized by a unique protein/phospholipid membrane layer. This unique structure makes them form a natural oil-in-water suspension which serves as energy stores for the germination and growth of seedlings (Guzha et al., 2023;Tzen and Huang, 1992). Isolated oleosomes from different sources have a spherical shape and possess diameters ranging from 0.2 to 2.5 μm controlled by the relative TAG to oleosin (structural proteins found on oleosome surface) ratio (Nikiforidis, 2019). ...
... w/w (Guzha et al., 2023;Tzen et al., 1993;Shimada and Hara-Nishimura, 2010;Deleu et al., 2010). Among surface proteins, oleosins are the main proteins which are small alkaline proteins with a molecular mass ranging from 15 to 26 kDa (Tzen and Huang, 1992). Amino acid sequence analysis of oleosins has shown the existence of three structural domains, including an amphipathic N-terminal domain, a central hydrophobic hairpin structure domain that is pinned in the TAG core, and an amphipathic α-helical domain near the C-terminus. ...
This study aimed to increase the physical stability of native sunflower oleosomes to expand their range of applications in food. The first objective was to increase the stability and functionality of oleosomes to lower pH since most food products require a pH of 5.5 or lower for microbial stability. Native sunflower oleosomes had a pI of 6.2. One particularly effective strategy for long-term stabilization, both physical and microbial, was the addition of 40% (w/w) glycerol to the oleosomes plus homogenization, which decreased the pI to 5.3 as well as decreasing oleosome size, narrowing the size distribution and increasing colloidal stability. Interfacial engineering of oleosomes by coating them with lecithin and the polysaccharides xanthan and gellan, effectively increased stability, and lowered their pI to 3.0 for lecithin and lower than 3.0 for xanthan. Coating oleosomes also caused a greater absolute value of the ζ-potential; for example, this amount was shifted to −20 mV at pH 4.0 for xanthan and to −28 mV at pH 4.0 for lecithin, which provides electrostatic stabilization. Polysaccharides also provide steric stabilization, which is superior. A significant increase in the diameter of coated oleosomes was observed with lecithin, xanthan and gellan. The oleosome sample with 40% glycerol showed high storage stability at 4 °C (over three months). The addition of glycerol also decreased the water activity of the oleosome suspension to 0.85, which could prevent microbial growth.
... In 1992, researchers first generated LD-like structures in vitro by extracting plant TAG, PLs and plant protein oleosins, which they named oil bodies, and then performed studies on plant seed lipids. 51 In 2003, a cell-free system based on microsomes was developed to generate LDs in vitro and identify the functions of caveolin 1/2, vimentin and phospholipase D in LD formation. The role of PA in controlling LD size was later discovered and demonstrated using artificial lipid emulsions. ...
Background
The study and synthesis of membrane organelles are becoming increasingly important, not only as simplified cellular models for corresponding molecular and metabolic studies but also for applications in synthetic biology of artificial cells and drug delivery vehicles. Lipid droplets (LDs) are central organelles in cellular lipid metabolism and are involved in almost all metabolic processes. Multiple studies have also demonstrated a high correlation between LDs and metabolic diseases. During these processes, LDs reveal a highly dynamic character, with their lipid fraction, protein composition and subcellular localisation constantly changing in response to metabolic demands. However, the molecular mechanisms underlying these functions have not been fully understood due to the limitations of cell biology approaches. Fortunately, developments in synthetic biology have provided a huge breakthrough for metabolism research, and methods for in vitro synthesis of LDs have been successfully established, with great advances in protein binding, lipid function, membrane dynamics and enzymatic reactions.
Aims and methods
In this review, we provide a comprehensive overview of the assembly and function of endogenous LDs, from the generation of lipid molecules to how they are assembled into LDs in the endoplasmic reticulum. In particular, we highlight two major classes of synthetic LD models for fabrication techniques and their recent advances in biology and explore their roles and challenges in achieving real applications of artificial LDs in the future.
... Oleosins are unique proteins present in plant seeds, that have a surfactant-like structure consisting of hydrophilic arms that flank a central hydrophobic hairpin. This structure is crucial for its role in stabilizing the lipid storage droplets called oleosomes [26,45,46]. Oleosins are believed to protect oleosomes from coalescing during extreme environmental conditions, like desiccation to moisture levels as low as 5-10 wt%, freezing winters, or several years of storage in a dry state until rehydration during seed germination [32,40]. ...
... In the native environment, the hydrophobic hairpin is believed to anchor into the triacylglyceride core of oleosomes [19,20]. The hydrophilic arms are facing the bulk phase and probably protecting oleosomes from coalescence [45,46]. ...
... Currently, it is unknown how these aggregates are affecting the emulsification performance and emulsification mechanism of oleosins. While pure oleosins (isolated from oilseeds or recombinantly produced), either alone or in combination with phospholipids, have been used earlier to stabilize oil-in-water emulsions, limited insights into the underlying stabilization mechanism are available [12,23,33,35,36,45]. Particularly, it is unclear whether the emulsion interface is stabilized by oleosin aggregates or by individual oleosins. ...
... Lipids and proteins are stored in seeds in lipid/oleosome and protein bodies (TAN-WILSON and WILSON, 2010;HUANG, 1994). The type of reserve in the seeds and its distribution in the tissues vary depending on the taxon of the plant and the development program of each species. ...
Safflower (Carthamus tinctorius L.) is a crop with wide commercial potential, due to the broad adaptability of cultivation and use conditions, but commercial initiatives are deficient. This scenario extends to academic research, which also focuses little on understanding the involved processes from the germination of its seeds to the correct management of adult plants. In this context, the current study seeks to identify the primary metabolites stored in the safflower seed and to evaluate how the mobilization of these reserves occurs during seed germination and seedling establishment. Safflower seeds of the cultivar S-351 produced in the experimental field of Universidade Federal de Jataí, from the second season of 2017/2018, were used. To obtain the seedlings, safflower seeds were sown in moistened sand with 60% retention capacity and kept at 25 °C. At 1, 2, 3, 4, 5, 8, 15 and 22 days after sowing, the seedlings were subjected to analysis of length and histological characterization of cotyledons, the latter of which also evaluated at 12 h after sowing. Biochemical (carbohydrate, protein, lipid and chlorophyll) and anatomical analyses were performed to assess reserve mobilization, both of which were evaluated at five germination times (12h, 3, 5, 8, 15 and 22 days after sowing). The data regarding the periods during reserve mobilization were subjected to regression analysis. The main source of reserve in safflower is lipids, followed by carbohydrates and proteins, with reductions of 37% for lipids, 3% for carbohydrates and 0.5% for proteins, during germination and seedling development. The mobilization of reserves of safflower seeds was accompanied by changes of cell features, which became vacualized and with multiple plastids, and by the synthesis of chlorophyll a, which peaked between 9 and 11 days after sowing, followed by the final reduction caused by senescence.
... The core of the oil droplets is comprised by triacylglycerols (vegetable oil) and are stabilized by phospholipids in combination with highly interfacially active interfacial proteins, called oleosins [10,12,18]. The oleosome interface is approximately 2.0-4.0 wt% of the oleosome total mass, and the ratio between phospholipids and oleosins at the interface is about 1:1 [13,15,24]. The oleosome interfacial molecules are selected by nature and create an interface around the oleosome lipid core that prevents their the coalescence [14]. ...
Oleosomes are natural oil droplets, present in all organisms and abundant in oilseeds. After their aqueous extraction from oilseeds, they can be directly utilized as oil droplets in food, cosmetics and all types of oil-in-water emulsion systems. However, to expand the potential uses of oleosomes as green ingredients and to valorize oilseeds as efficient as possible, we explored their emulsifying ability. Oleosomes were extracted from rapeseeds, and 10.0 wt% oil-in-water emulsions were created after homogenization with 0.5-6.0 wt% oleosomes, and the droplet size of the emulsions and their structure was measured by laser diffraction and confocal laser scanning microscopy (CLSM), respectively. The emulsion with an oleosome concentration lower than 1.0 wt% gave unstable emulsions with visible free oil. At oleosome concentrations at 1.5 wt% or higher, we obtained stable emulsions with droplet sizes between 2.0 and 12.0 µm. To investigate the role of the oleosome interfacial molecules in stabilizing emulsions we also studied their emulsifying and interfacial properties (using drop tensiometry) after isolating them from the oleosome structure. Both oleosomes and their isolated interfacial molecules exhibited a similar behavior on the oil-water interfaces, forming predominantly elastic interfacial films, and also showed a similar emulsifying ability. Our results show that oleosomes are not stabilizing the oil-in-water emulsions as intact particles, but they provide their interfacial molecules, which are enough to stabilize an oil-water surface up to about 2 times bigger than the initial oleosome surface. The understanding of the behavior of oleosomes as emulsifiers, opens many possibilities to use oleosomes as alternative to synthetic emulsifiers in food and pharma applications.
... Oleosomes have a triacylglycerol (TAG) core, which is surrounded by a monolayer of phospholipids with membrane proteins (Frandsen, Mundy, & Tzen, 2001; J. T.C. Tzen & Huang, 1992; Jason T. C. Tzen, 2012). In the conventional oil extraction process, oleosomes are disrupted to obtain the TAG core. ...
... After soaking, the seeds are blended to disrupt the cell walls, leading to the extraction of the oleosomes into the water phase due to their hydrophilic surface (J. T.C. Tzen & Huang, 1992). ...
Oil seeds contain 10-20 wt% proteins and up to 50 wt% oil, organised in micron-sized oil droplets, named oleosomes. During oil extraction, which takes place using mechanical pressing or organic solvents or a combi- nation of them, oleosomes are ruptured, and the oil is obtained. The oil extraction process might lead to the degradation of both the contained oil and proteins, therefore, as an effort to have a minimum impact on the quality of both, an aqueous extraction has been suggested, where oleosomes and proteins are simultaneously extracted. Oleosomes, being oil droplets themselves, can be used in emulsion-like food products, however, their extraction and purification from proteins is energy intensive. For a better understanding of the extraction and separation of oleosomes and proteins from sunflower seeds, we here explore the mass balance of oleosomes and proteins during each extraction step. Additionally, we investigate the effect of the process steps on oleosome physical stability. At the initial extract, oleosomes and proteins were at a 3:1 ratio, with an oleosome diameter of up to 10 μm. Three centrifugation steps were needed to separate proteins since the cream obtained had an oleosome/protein ratio close to 20:1. However, the removal of proteins had a significant effect on droplet coalescence, since oleosomes with a diameter up to 40–50 μm were observed. After a homogenisation step though, the oil droplets regained their initial size. Besides the effect on the physical stability of the sunflower oleosomes, the oleosome purification affected the obtaining yield, as from 87 wt% after the first extraction step, dropped to 66 wt%. By providing the mass balances during the oleosome/protein extraction from sunflower seeds, we highlight the effect of the sunflower oleosome purification steps on the obtaining yield and the role of the co-extracted storage proteins on their physical stability. Unlikely oleosomes from other sources, those derived from sunflower seeds, are prompt to coalescence when storage proteins are not present. With this insight, we provide tools for targeted sunflower oleosome and protein extraction depending on the potential applications and yield needed.
1.
... Alongside proteins, phospholipids also play a role in the unique structure and stability of the interface due to the dense crystalline (hard) phase. This LD model was first characterized in mature maize seeds [20], followed by their characterization in diverse organisms [1,4,21]. In addition to TAGs, the LD core can contain sterols, wax esters, steryl esters, or carotenoids in some organisms [14,[22][23][24]. ...
... LDs can be isolated using a flotation-centrifugation method (see Figure 3). This LD extraction technique was developed for the lipidomic, proteomic, and structural analysis of LDs [20,28]. A flow diagram of this method is shown in Figure 3. ...
... A flow diagram of this method is shown in Figure 3. To break the cell walls, several mechanical methods can be used, including grinding, pressing, and applying high pressure [20,26,82]. However, during these procedures, LDs can be oxidized in the presence of water and air, and this reaction is catalyzed by lipoxygenase [83]. ...
Plant and algal LDs are gaining popularity as a promising non-chemical technology for the production of lipids and oils. In general, these organelles are composed of a neutral lipid core surrounded by a phospholipid monolayer and various surface-associated proteins. Many studies have shown that LDs are involved in numerous biological processes such as lipid trafficking and signaling, membrane remodeling, and intercellular organelle communications. To fully exploit the potential of LDs for scientific research and commercial applications, it is important to develop suitable extraction processes that preserve their properties and functions. However, research on LD extraction strategies is limited. This review first describes recent progress in understanding the characteristics of LDs, and then systematically introduces LD extraction strategies. Finally, the potential functions and applications of LDs in various fields are discussed. Overall, this review provides valuable insights into the properties and functions of LDs, as well as potential approaches for their extraction and utilization. It is hoped that these findings will inspire further research and innovation in the field of LD-based technology.
