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Cai Y, Horn PJ. Packaging "vegetable oils": Insights into plant lipid droplet proteins. PLANT PHYSIOLOGY 2024:kiae533. [PMID: 39566075 DOI: 10.1093/plphys/kiae533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Accepted: 09/06/2024] [Indexed: 11/22/2024]
Abstract
Plant neutral lipids, also known as "vegetable oils", are synthesized within the endoplasmic reticulum (ER) membrane and packaged into subcellular compartments called lipid droplets (LDs) for stable storage in the cytoplasm. The biogenesis, modulation, and degradation of cytoplasmic LDs in plant cells are orchestrated by a variety of proteins localized to the ER, LDs, and peroxisomes. Recent studies of these LD-related proteins have greatly advanced our understanding of LDs not only as steady oil depots in seeds but also as dynamic cell organelles involved in numerous physiological processes in different tissues and developmental stages of plants. In the past 2 decades, technology advances in proteomics, transcriptomics, genome sequencing, cellular imaging and protein structural modeling have markedly expanded the inventory of LD-related proteins, provided unprecedented structural and functional insights into the protein machinery modulating LDs in plant cells, and shed new light on the functions of LDs in nonseed plant tissues as well as in unicellular algae. Here, we review critical advances in revealing new LD proteins in various plant tissues, point out structural and mechanistic insights into key proteins in LD biogenesis and dynamic modulation, and discuss future perspectives on bridging our knowledge gaps in plant LD biology.
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Affiliation(s)
- Yingqi Cai
- BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, TX, 76203, USA
| | - Patrick J Horn
- BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, TX, 76203, USA
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2
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Demchenko K, Zdyb A, Feussner I, Pawlowski K. Analysis of the subcellular localisation of lipoxygenase in legume and actinorhizal nodules. PLANT BIOLOGY (STUTTGART, GERMANY) 2012; 14:56-63. [PMID: 21973171 DOI: 10.1111/j.1438-8677.2011.00480.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Plant lipoxygenases (LOXs; EC 1.13.11.12) catalyse the oxygenation of polyunsaturated fatty acids, linoleic (18:2) and α-linolenic acid (18:3(n-3)) and are involved in processes such as stress responses and development. Depending on the regio-specificity of a LOX, the incorporation of molecular oxygen leads to formation of 9- or 13-fatty acid hydroperoxides, which are used by LOX itself as well as by members of at least six different enzyme families to form a series of biologically active molecules, collectively called oxylipins. The best characterised oxylipins are the jasmonates: jasmonic acid (JA) and its isoleucine conjugate that are signalling compounds in vegetative and propagative plant development. In several types of nitrogen-fixing root nodules, LOX expression and/or activity is induced during nodule development. Allene oxide cyclase (AOC), a committed enzyme of the JA biosynthetic pathway, has been shown to localise to plastids of nodules of one legume and two actinorhizal plants, Medicago truncatula, Datisca glomerata and Casuarina glauca, respectively. Using an antibody that recognises several types of LOX interspecifically, LOX protein levels were compared in roots and nodules of these plants, showing no significant differences and no obvious nodule-specific isoforms. A comparison of the cell-specific localisation of LOXs and AOC led to the conclusion that (i) only cytosolic LOXs were detected although it is generally assumed that the (13S)-hydroperoxy α-linolenic acid for JA biosynthesis is produced in the plastids, and (ii) in cells of the nodule vascular tissue that contain AOC, no LOX protein could be detected.
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Affiliation(s)
- K Demchenko
- Albrecht-von-Haller Institute for Plant Sciences, Department of Plant Biochemistry, Georg-August-University Göttingen, Göttingen, Germany
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Witzel K, Weidner A, Surabhi GK, Börner A, Mock HP. Salt stress-induced alterations in the root proteome of barley genotypes with contrasting response towards salinity. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:3545-57. [PMID: 19671579 PMCID: PMC2724703 DOI: 10.1093/jxb/erp198] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 05/20/2009] [Accepted: 05/21/2009] [Indexed: 05/18/2023]
Abstract
In addition to drought and extreme temperatures, soil salinity represents a growing threat to crop productivity. Among the cereal crops, barley is considered as notably salt tolerant, and cultivars show considerable variation for tolerance towards salinity stress. In order to unravel the molecular mechanisms underlying salt stress tolerance and to utilize the natural genetic variation of barley accessions, a series of hydroponics-based salinity stress experiments was conducted using two genetic mapping parents, cvs Steptoe and Morex, which display contrasting levels of salinity tolerance. The proteome of roots from both genotypes was investigated as displayed by two-dimensional gel electrophoresis, and comparisons were made between plants grown under non-saline and saline conditions. Multivariate analysis of the resulting protein patterns revealed cultivar-specific and salt stress-responsive protein expression. Mass spectrometry-based identification was successful for 26 out of 39 selected protein spots. Hierarchical clustering was applied to detect similar protein expression patterns. Among those, two proteins involved in the glutathione-based detoxification of reactive oxygen species (ROS) were more abundant in the tolerant genotype, while proteins involved in iron uptake were expressed at a higher level in the sensitive one. This study emphasizes the role of proteins involved in ROS detoxification during salinity stress, and identified potential candidates for increasing salt tolerance in barley.
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Zweytick D, Athenstaedt K, Daum G. Intracellular lipid particles of eukaryotic cells. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1469:101-20. [PMID: 10998572 DOI: 10.1016/s0005-2736(00)00294-7] [Citation(s) in RCA: 246] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In this review article we describe characterization of intracellular lipid particles of three different eukaryotic species, namely mammalian cells, plants and yeast. Lipid particles of all types of cells share a general structure. A hydrophobic core of neutral lipids is surrounded by a membrane monolayer of phospholipids which contains a minor amount of proteins. Whereas lipid particles from mammalian cells and plants harbor specific classes of polypeptides, mainly perilipins and oleosins, respectively, yeast lipid particles contain a more complex set of enzymes which are involved in lipid biosynthesis. Function of lipid particles as storage compartment and metabolic organelle, and their interaction with other subcellular fractions are discussed. Furthermore, models for the biogenesis of lipid particles are presented and compared among the different species.
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Affiliation(s)
- D Zweytick
- Institut für Biochemie und Lebensmittelchemie, Technische Universität, Petersgasse 12/II, A-8010, Graz, Austria
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Noll F, May C, Kindl H. Phospholipid monolayer of plant lipid bodies attacked by phospholipase A2 shows 80 nm holes analyzed by atomic force microscopy. Biophys Chem 2000; 86:29-35. [PMID: 11011697 DOI: 10.1016/s0301-4622(00)00156-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In plant storage tissue, lipid bodies are composed of triacylglycerides and surrounded by a phospholipid monolayer which is stabilized by oleosins. At the onset of lipid body mobilization, cells express phospholipase A2, which partially degrades the monolayer and thus provides access for the subsequently acting triacylglyceride degrading enzymes. Analyzing the lipid body surface by atomic force microscopy we show that, at the stage of maximal phospholipase A2 expression, the monolayer contains holes of approximately 80 nm in width and 2.45 +/- 0.46 nm in depth. Non-contact mode imaging was performed with a lateral resolution of approximately 10 nm and a vertical resolution of less than 0.1 nm. The depth of the holes corresponds to the width of the monolayer, while the width of the channels is sufficiently large to provide access to 100 kDa enzymes, such as lipoxygenase and lipases.
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Affiliation(s)
- F Noll
- Institute of Physical Chemistry, Nuclear Chemistry, and Macromolecular Chemistry, Philipps-University, Marburg, Germany.
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May C, Höhne M, Gnau P, Schwennesen K, Kindl H. The N-terminal beta-barrel structure of lipid body lipoxygenase mediates its binding to liposomes and lipid bodies. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:1100-9. [PMID: 10672019 DOI: 10.1046/j.1432-1327.2000.01105.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Phospholipase A2 and a particular isoform of lipoxygenase are synthesized and transferred to lipid bodies during the stage of triacylglycerol mobilization in germinating cucumber seedlings. Lipid body lipoxygenase (LBLOX) is post-translationally transported to lipid bodies without proteolytic modification. Fractionation of homogenates from cucumber cotyledons or transgenic tobacco leaves expressing LBLOX showed that a small but significant amount was detectable in the microsomal fraction. A beta-barrel-forming N-terminal domain in the structure of LBLOX, as deduced from sequence data, was shown to be crucial for selective intracellular transport from the cytosol to lipid bodies. Although a specific signal sequence for targeting protein domains to the lipid bodies could not be established, it was evident that the beta-barrel represents a membrane-binding domain that is functionally comparable with the C2 domains of mammalian phospholipases. The intact beta-barrel of LBLOX was demonstrated to be sufficient to target in vitro a fusion protein of LBLOX beta-barrel with glutathione S-transferase (GST) to lipid bodies. In addition, binding experiments on liposomes using lipoxygenase isoforms, LBLOX deletions and the GST-fusion protein confirmed the role of the beta-barrel as the membrane-targeting domain. In this respect, the cucumber LBLOX differs from cytosolic isoforms in cucumber and from the soybean LOX-1. When the beta-barrel of LBLOX was destroyed by insertion of an additional peptide sequence, its ability to target proteins to membranes was abolished.
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Affiliation(s)
- C May
- Fachbereich Chemie der Philipps-Universität, Marburg, Germany
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Wang C, Croft KP, Jarlfors U, Hildebrand DF. Subcellular localization studies indicate that lipoxygenases 1 to 6 are not involved in lipid mobilization during soybean germination. PLANT PHYSIOLOGY 1999; 120:227-236. [PMID: 10318700 PMCID: PMC59254 DOI: 10.1104/pp.120.1.227] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/1998] [Accepted: 01/19/1999] [Indexed: 05/23/2023]
Abstract
Soybean (Glycine max) lipoxygenase (LOX) has been proposed to be involved in reserve lipid mobilization during germination. Here, subcellular fractionation studies show that LOX1, -2, -3, -4, -5, and -6 isozymes were associated with the soluble fraction but not with purified oil bodies. The purified oil bodies contained small amounts of LOX1 (<0.01% total activity), which apparently is an artifact of the purification process. Immunogold labeling indicated that, in cotyledon parenchyma cells of LOX wild-type seeds that had soaked and germinated for 4 d, the majority of LOX protein was present in the cytoplasm. In 4-d-germinated cotyledons of a LOX1/2/3 triple null mutant (L0), a small amount of label was found in the cytoplasm. In epidermal cells, LOX appeared in vacuoles of both wild-type and L0 germinated seeds. No LOXs cross-reacting with seed LOX antibodies were found to be associated with the cell wall, plasma membrane, oil bodies, or mitochondria. Lipid analysis showed that degradation rates of total lipids and triacylglycerols between the wild type and L0 were not significantly different. These results suggest that LOX1, -2, -3, -4, -5, and -6 are not directly involved in reserve lipid mobilization during soybean germination.
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Affiliation(s)
- C Wang
- Department of Agronomy (C.W., K.P.C.C., D.F.H.)
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May C, Preisig-Müller R, Höhne M, Gnau P, Kindl H. A phospholipase A2 is transiently synthesized during seed germination and localized to lipid bodies. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1393:267-76. [PMID: 9748624 DOI: 10.1016/s0005-2760(98)00081-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A patatin-like protein is present in the storage tissue of cucumber seedlings during the stage of fat mobilization. The cucumber protein is a homologue of a glycoprotein which in potatoes accounts for most of the total protein content of tubers. Following preparation of a cucumber cDNA library representing the developmental stage of cotyledons of 1 day old germinating seeds we isolated and characterized a clone encoding a patatin-like protein. Antibodies raised against the protein expressed in bacteria were used for immunodetection in subcellular fractions of cucumber seedlings. It was shown that the patatin-like protein was virtually exclusively confined to lipid bodies. The protein expressed in bacteria was characterized in vitro by its esterase activity acting on monoacylglycerols and phospholipids. Detailed analysis using various forms of phosphatidyl choline as substrates demonstrated that the patatin-like protein is a phospholipase A2 acting on palmitoyl, linoleoyl and hydroperoxidized linoleoyl groups equally well. Studying the temporal and tissue-specific expression of patatin-like protein mRNA we showed its appearance exclusively during fat catabolism. As maximal amounts of the protein were found at an early stage of mobilization and confined to lipid bodies, we propose that the patatin-like hydrolase is involved in lipid body mobilization.
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Affiliation(s)
- C May
- Fachbereich Chemie, Philipps-Universität, Marburg, Germany.
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Höhne M, Nellen A, Schwennesen K, Kindl H. Lipid body lipoxygenase characterized by protein fragmentation, cDNA sequence and very early expression of the enzyme during germination of cucumber seeds. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 241:6-11. [PMID: 8898881 DOI: 10.1111/j.1432-1033.1996.0006t.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Lipid bodies are cellular compartments containing triacylglycerols. They are encompassed by a phospholipid monolayer and decorated with characteristic proteins. In plants, lipid bodies are synthesized during seed formation but acquire new proteins during seed germination. In germinating cucumber (Cucumis sativus) seeds, the set of newly synthesized proteins appearing in the lipid bodies at the early stage of triacylglycerol mobilization comprises a special form of lipoxygenase. We isolated the lipid body lipoxygenase and characterized fragments prepared by limited proteolysis and cleavage with cyanogen bromide. A very early expression of lipid body lipoxygenase was found by studying the rate of de novo synthesis of lipoxygenase forms during germination. This allowed a clear distinction of this enzyme from other lipoxygenase isoforms. Hence, for determining the molecular structure of lipid body lipoxygenase we analyzed a cDNA prepared from mRNA of cotyledons at day 1 of germination. From the cDNA sequence, oligonucleotides were derived that specifically detected lipid body lipoxygenase mRNA on northern blots. The very early expression of lipid body lipoxygenase was corroborated by this approach. Good agreement was observed between the amino acid sequence deduced from the cDNA sequence and the peptide structures analyzed biochemically. In particular, the cleavage products of cyanogen bromide treatment indicated that we had isolated the lipid body lipoxygenase cDNA. The sequence data show a lipoxygenase form characterized by a molecular mass of 99655 Da, which is significantly higher than the molecular masses of the cytosolic forms. Compared to the cytosolic forms that exhibit a molecular mass of 95 kDa, the lipid body form has an N-terminal extension of 34 amino acid residues. No evidence for a cotranslational or post-translational proteolytic processing was obtained by the size comparison of the in vitro-translated lipoxygenase and the lipid body form.
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Affiliation(s)
- M Höhne
- Fachbereich Chemie, Philipps-Universität Marburg, Germany
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Feussner I, Kühn H. The lipid body lipoxygenase from cucumber seedlings exhibits unusual reaction specificity. FEBS Lett 1995; 367:12-4. [PMID: 7601276 DOI: 10.1016/0014-5793(95)00531-d] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The lipid body lipoxygenase of cucumber seedlings is at a high level expressed during the germinating process which is the stage of triglyceride mobilisation. This enzyme exhibits an unusual positional specificity which has not been described so far for any plant and animal lipoxygenase. The purified enzyme converts arachidonic acid to 15-S-hydroperoxy-5Z,8Z,11Z, 13E-eicosatetraenoic acid (15S-HPETE), 12-S-hydroperoxy-5Z, 8Z, 10E, 14Z-eicosatetraenoic acid (12S-HPETE), and 8-S-hydroperoxy-5Z,9E,11Z,14Z-eicosatetraenoic acid (8S-HPETE) in a ratio of 76:4:20 with the corresponding R-isomers being only minor contaminants. Binding to the lipid bodies enhances the arachidonic acid dioxygenase activity more than 4-times and alters positional specificity of the enzyme in favour of 8-S-hydroperoxy-5Z,9E,11Z,14Z-eicosatetraenoic acid (8S-HPETE) formation.
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Affiliation(s)
- I Feussner
- Institut für Pflanzenbiochemie, Halle, Germany
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Preisig-Müller R, Kindl H. Thiolase mRNA translated in vitro yields a peptide with a putative N-terminal presequence. PLANT MOLECULAR BIOLOGY 1993; 22:59-66. [PMID: 8098965 DOI: 10.1007/bf00038995] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Thiolase is part of the fatty acid oxidation machinery which in plants is located within glyoxysomes or peroxisomes. In cucumber cotyledons, proteolytic modification of thiolase takes place during the transfer of the cytosolic precursor into glyoxysomes prior to the intraorganellar assembly of the mature enzyme. This was shown by size comparison of the in vitro synthesized precursor and the 45 kDa subunit of the homodimeric glyoxysomal form. We isolated a full-length cDNA clone encoding the 48,539 Da precursor of thiolase. This plant protein displayed 40% and 47% identity with the precursor of fungal peroxisomal thiolase and human peroxisomal thiolase, respectively. Compared to bacterial thiolases, the precursor of the plant enzyme was distinguished by an N-terminal extension of 34 amino acid residues. This putative targeting sequence of cucumber thiolase shows similarities with the cleavable presequences of rat peroxisomal thiolase and plant peroxisomal malate dehydrogenase.
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Kindl H. Fatty acid degradation in plant peroxisomes: function and biosynthesis of the enzymes involved. Biochimie 1993; 75:225-30. [PMID: 8507684 DOI: 10.1016/0300-9084(93)90080-c] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In plants, the fatty acid oxidation enzyme apparatus is exclusively located within glyoxysomes or peroxisomes. Following the formation of the CoA-ester, the machinery for the degradation of endogenous fatty acids consists of acyl-CoA oxidase, D-3-hydroxyacyl-CoA hydrolyase, 2,3-enoyl-CoA isomerase, isoenzymes of the multifunctional protein and thiolase. The multiple location of particular enzyme activities on different species of protein is discussed in detail. In cucumber cotyledons, the multifunctional protein exhibits a C-terminal targeting signal, -PRM like other glyoxysomal or leaf peroxisomal proteins. In contrast, proteolytic modification takes place at the N-terminus of thiolase and malate dehydrogenase. Thus, distinct mechanisms are envisaged to take place during the transfer of the cytosolic precursor into glyoxysomes prior to the intra-organellar assembly of the mature enzyme.
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Affiliation(s)
- H Kindl
- University of Marburg, Department of Chemistry, Germany
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Feussner I, Kindl H. A lipoxygenase is the main lipid body protein in cucumber and soybean cotyledons during the stage of triglyceride mobilization. FEBS Lett 1992; 298:223-5. [PMID: 1544449 DOI: 10.1016/0014-5793(92)80062-l] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The 90-kDa lipid body protein characterized earlier by its high expression during the stage of fat degradation was identified as a form of lipoxygenase. This organelle form was compared with lipoxygenase species purified from the cytosol. It is further shown that the antibodies raised against the lipid body membrane lipoxygenase from cucumber cotyledons cross-react with both cytosolic and lipid body lipoxygenase from soybean.
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Affiliation(s)
- I Feussner
- Biochemie, FB Chemie, Universität Marburg, Germany
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