Caleosin

Oil bodies (OBs) function as organelles that store lipids in plant seeds. An oil body (OB) is encased by a membrane composed of proteins (e.g., oleosins, caleosins, and steroleosins) and a phospholipid monolayer. The distinctive protein-phospholipid membrane architecture of OBs imparts exceptional stability even in extreme environments, thereby sparking increasing interest in their structure and properties. However, a comprehensive understanding of the structure-activity relationships determining the stability and properties of oil bodies requires a more profound exploration of the associated membrane proteins, an aspect that remains relatively unexplored...

The caleosins are encoded by multi-gene families in Arabidopsis thaliana and other plant species. This work investigates the role of two family members, RD20/CLO3 and CLO7, in flowering transition and in root development in response to ABA treatment. Gene expression of the caleosin RD20/CLO3 is induced by ABA in the root tissues and RD20/CLO3 has a negative affect on the total number of lateral roots as well as the length of the lateral roots in response to ABA treatment. The rd20/clo3 mutant has more and longer lateral roots in response to ABA treatment compared to the wild-type, showing that RD20/CLO3 plays a role in the ABA signaling pathway affecting this trait...

RESPONSIVE TO DESSICATION 20 (RD20) is a member of the caleosin family, which is involved in plant growth and development, signal transduction, abiotic stress and plant immunity. However, the molecular mechanism of the biological function of RD20 in turnip is still largely unknown. This study aimed to characterise the roles of BrRD20 during abiotic stress resistance and their responses in various abiotic stresses by isolating BrRD20 (MK896873) from 'Tsuda' turnip. Quantitative polymerase chain reaction analysis showed that the highest expression levels of BrRD20 occurred in the petal, followed by the leaf, bud and red root epidermis, with tissue specificity...

Lipid droplets (LDs) of seed tissues are storage organelles for triacylglycerols (TAGs) that provide the energy and carbon for seedling establishment. In the major route of LD degradation (lipolysis), TAGs are mobilized by lipases. However, LDs may also be degraded via lipophagy, a type of selective autophagy, which mediates LD delivery to vacuoles or lysosomes. The exact mechanisms of LD degradation and the mobilization of their content in plants remain unresolved. Here, we provide evidence that LDs are degraded via a process morphologically resembling microlipophagy in Arabidopsis (Arabidopsis thaliana) seedlings...

Lipid droplets (LD) is an important intracellular organelle for triacylglycerols (TAGs) storage. A variety of proteins on the surface of LD coordinately control the contents, size, stability and biogenesis of LD. However, the LD proteins in Chinese hickory (Carya cathayensis) nuts, which rich in oil and composed of unsaturated fatty acids, have not been identified and their roles in LD formation still remain largely unknown. In present study, LD fractions from three developmental stages of Chinese hickory seed were enriched and the LD fraction accumulated proteins were then isolated and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS)...

The tubers of the widely distributed Cyperus esculentus are rich in oil, and therefore, the plant is considered to have a high utilization value in the vegetable oil industry. Oleosins and caleosins are lipid-associated proteins found in oil bodies of seeds; however oleosins and caleosins genes have not been identified in C. esculentus. In this study, we performed transcriptome sequencing and lipid metabolome analysis of C. esculentus tubers at four developmental stages to obtain the information on their genetic profile, expression trends, and metabolites in oil accumulation pathways...

Oil bodies, also known as lipid droplets or oil droplets, are important organelles for oil storage in plant cells. The oil body is composed of a monolayer of phospholipid membrane encapsulating neutral fatty acids, and a variety of membrane proteins are embedded in the membrane, including oleosin, caleosin and steroleosin, of which oleosin accounts for 80%-90%. Oleosin plays important biological roles in various biological roles, such as affecting the size and stability of oil bodies, formation and degradation of oil bodies, lipid metabolism, and seed maturation and germination...

Walnuts are abundant in oil content, especially for polyunsaturated fatty acids, but the understanding of their formation is limited. We collected walnut ( Juglans regia L.) kernels at 60, 74, 88, 102, 116, 130, and 144 days after pollination (designated S1-S7). The ultrastructure and accumulation of oil bodies (OBs) were observed using transmission electron microscopy (TEM), and the oil content, fatty acid composition, and proteomic changes in walnut kernels were determined. The oil content and OB accumulation increased during the development and rose sharply from S1 to S3 stages, which are considered the key lipogenesis stage...

BACKGROUND: Caleosin/peroxygenases (CLO/PXGs) are a family of multifunctional proteins that are ubiquitous in land plants and also found in some fungi and green algae. CLO/PXGs were initially described as a class of plant lipid-associated proteins with some similarities to the oleosins that stabilize lipid droplets (LDs) in storage tissues such as seeds. However, we now know that CLO/PXGs have more complex structure, distribution and functions than oleosins. Structurally, CLO/PXGs share conserved domains that confer specific biochemical features with diverse localizations and functions...

Plant cells store energy in oil bodies constructed by structural proteins such as oleosins and caleosins. Although oil bodies usually accumulate in the seed and pollen of plants, caleosins are present in various organs and organelles. This issue, coupled with the diverse activities of caleosins, complicates the description of these oleo-proteins. Therefore, the current article proposes a new classification based on the bioinformatics analysis of the transmembrane topology of caleosins. Accordingly, the non-membrane class are the most abundant and diverse caleosins, especially in lower plants...

Walnut ( Juglans regia ) is an important woody oil-bearing plant with high nutritional value. For better understanding of the underlying molecular mechanisms of its oil accumulation in the Qinghai Plateau, in this study we monitored walnut fruit development, and 15 cDNA libraries were constructed from walnut seed kernels collected at 72, 79, 93, 118 and 135 days after flowering (DAF). The candidate genes were identified using sequencing and expression analysis. The results showed that the oil content in the kernels increased dramatically in late July and reached the maximum value of 69% in mature seed...

The peroxygenase pathway plays pivotal roles in plant responses to oxidative stress and other environmental stressors. Analysis of a network of co-expressed stress-regulated rice genes demonstrated that expression of OsPXG9 is negatively correlated with expression of genes involved in jasmonic acid biosynthesis. DNA sequence analysis and structure/function studies reveal that OsPXG9 is a caleosin-like peroxygenase with amphipathic α-helices that localizes to lipid droplets in rice cells. Enzymatic studies demonstrate that 12-epoxidation is slightly more favorable with 9(S)-hydroperoxyoctadecatrienoic acid than with 9(S)-hydroperoxyoctadecadienoic acid as substrate...

Lipid droplets, also known as oil bodies or lipid bodies, are plant organelles that compartmentalize neutral lipids as a hydrophobic matrix covered by proteins embedded in a phospholipid monolayer. Some of these proteins have been known for decades, such as oleosins, caleosins, and steroleosins, whereas a host of others have been discovered more recently with various levels of abundance on lipid droplets, depending on the tissue and developmental stage. In addition to a growing inventory of lipid droplet proteins, the subcellular machinery that contributes to the biogenesis and degradation of lipid droplets is being identified and attention is turning to more mechanistic questions regarding lipid droplet dynamics...

The investigation of the caleosin CLO7 in relation to heterotrimeric G-protein signalling in Arabidopsis showed that the gene plays a role in seed germination and embryo viability. The caleosin CLO7 belongs to a multi-gene family of calcium-binding proteins which are characterized by single EF-hand motifs. Other members of the caleosin gene family have been shown to affect transpiration and seed germination as well as play a role in both abiotic and biotic stress responses. The proteins are associated with lipid droplets/oil bodies and some members of the gene family have been shown to have peroxygenase activity...

Artificial oil bodies covered by a recombinant surface protein, caleosin fused with histatin 3 (a major human salivary peptide), were employed to explore the relative astringency of eight tea catechins. The results showed that gallate-type catechins were more astringent than non-gallate-type catechins, with an astringency order of epicatechin gallate > epigallocatechin gallate > gallocatechin gallate > catechin gallate > epigallocatechin > epicatechin > gallocatechin > catechin...

Oil-body-membrane proteins (OBMPs) are essential structural molecules of oil bodies and also versatile metabolic enzymes involved in multiple cellular processes such as lipid metabolism, hormone signaling and stress responses. However, the global landscape for OBMP genes in oil crops is still lacking. Here, we performed genome-wide identification and characterization of OBMP genes in polyploid crop Brassica napus . B. napus contains up to 88 BnaOBMP genes including 53 oleosins, 20 caleosins and 15 steroleosins...

Lipid assimilation, storage, and turnover impact growth, development, and virulence in many microbial pathogens including fungi. Perilipins are proteins associated with lipid droplets (LDs) that mediate their assembly and turnover. Here, we characterized the Beauveria bassiana ( BbPlin1 ) perilipin. BbPlin1 expression was higher in minimal media than in rich media, and, using a BbPlin1::eGFP fusion protein, the protein was shown to be co-localized to LDs, with the high expression seen during infection and proliferation within the insect ( Galleria mellonella ) host that dramatically decreased to almost no expression during fungal outgrowth on cadavers including in conidia, but that BbPlin1 production resumed in the conidia once placed in nutrient-containing media allowing for germination and growth...

Caleosins are lipid droplet- and endoplasmic reticulum-associated proteins. To investigate their functions in oil accumulation, expression levels of caleosins in developing seeds of Arabidopsis thaliana were examined and four seed-expressed caleosins (CLO1, CLO2, CLO4, and CLO6) were identified. The four single mutants showed similar minor changes of fatty acid composition in seeds. Two double mutants (clo1 clo2 and clo1×clo2) demonstrated distinct changes of fatty acid composition, a 16-23% decrease of oil content, and a 10-13% decrease of seed weight...

In barley, incubation of primary dormant (D1) grains on water under conditions that do not allow germination, i.e. 30°C in air and 15°C or 30°C in 5% O2, induces a secondary dormancy (D2) expressed as a loss of the ability to germinate at 15°C in air. The aim of this study was to compare the proteome of barley embryos isolated from D1 grains and D2 ones after induction of D2 at 30°C or in hypoxia at 15 or 30°C. Total soluble proteins were analysed by 2DE gel-based proteomics, allowing the selection of 130 differentially accumulated proteins (DAPs) among 1575 detected spots...

Our paper describes the potential roles of lipid droplets of Taxus media cell suspension in the biosynthesis and secretion of paclitaxel and, therefore, highlights their involvement in improving its production. Paclitaxel (PTX) is a highly potent anticancer drug that is mainly produced using Taxus sp. cell suspension cultures. The main purpose of the current study is to characterize cellular LDs from T. media cell suspension with a particular focus on the biological connection of their associated proteins, the caleosins (CLOs), with the biosynthesis and secretion of PTX...