Controlling Styrene Maleic Acid Lipid Particles through RAFT.

PubMed

Smith, Anton A A; Autzen, Henriette E; Laursen, Tomas; Wu, Vincent; Yen, Max; Hall, Aaron; Hansen, Scott D; Cheng, Yifan; Xu, Ting

2017-11-13

The ability of styrene maleic acid copolymers to dissolve lipid membranes into nanosized lipid particles is a facile method of obtaining membrane proteins in solubilized lipid discs while conserving part of their native lipid environment. While the currently used copolymers can readily extract membrane proteins in native nanodiscs, their highly disperse composition is likely to influence the dispersity of the discs as well as the extraction efficiency. In this study, reversible addition-fragmentation chain transfer was used to control the polymer architecture and dispersity of molecular weights with a high-precision. Based on Monte Carlo simulations of the polymerizations, the monomer composition was predicted and allowed a structure-function analysis of the polymer architecture, in relation to their ability to assemble into lipid nanoparticles. We show that a higher degree of control of the polymer architecture generates more homogeneous samples. We hypothesize that low dispersity copolymers, with control of polymer architecture are an ideal framework for the rational design of polymers for customized isolation and characterization of integral membrane proteins in native lipid bilayer systems.

Synthesis of Lipidated Proteins.

PubMed

Mejuch, Tom; Waldmann, Herbert

2016-08-17

Protein lipidation is one of the major post-translational modifications (PTM) of proteins. The attachment of the lipid moiety frequently determines the localization and the function of the lipoproteins. Lipidated proteins participate in many essential biological processes in eukaryotic cells, including vesicular trafficking, signal transduction, and regulation of the immune response. Malfunction of these cellular processes usually leads to various diseases such as cancer. Understanding the mechanism of cellular signaling and identifying the protein-protein and protein-lipid interactions in which the lipoproteins are involved is a crucial task. To achieve these goals, fully functional lipidated proteins are required. However, access to lipoproteins by means of standard expression is often rather limited. Therefore, semisynthetic methods, involving the synthesis of lipidated peptides and their subsequent chemoselective ligation to yield full-length lipoproteins, were developed. In this Review we summarize the commonly used methods for lipoprotein synthesis and the development of the corresponding chemoselective ligation techniques. Several key studies involving full-length semisynthetic lipidated Ras, Rheb, and LC3 proteins are presented.

Phloem proteomics reveals new lipid-binding proteins with a putative role in lipid-mediated signaling

DOE PAGES

Barbaglia, Allison M.; Tamot, Banita; Greve, Veronica; ...

2016-04-28

Global climate changes inversely affect our ability to grow the food required for an increasing world population. To combat future crop loss due to abiotic stress, we need to understand the signals responsible for changes in plant development and the resulting adaptations, especially the signaling molecules traveling long-distance through the plant phloem. Using a proteomics approach, we had identified several putative lipid-binding proteins in the phloem exudates. Simultaneously, we identified several complex lipids as well as jasmonates. These findings prompted us to propose that phloem (phospho-) lipids could act as long-distance developmental signals in response to abiotic stress, and thatmore » they are released, sensed, and moved by phloem lipid-binding proteins (Benning et al., 2012). Indeed, the proteins we identified include lipases that could release a signaling lipid into the phloem, putative receptor components, and proteins that could mediate lipid-movement. To test this possible protein-based lipid-signaling pathway, three of the proteins, which could potentially act in a relay, are characterized here: (I) a putative GDSL-motif lipase (II) a PIG-P-like protein, with a possible receptor-like function; (III) and PLAFP (phloem lipid-associated family protein), a predicted lipid-binding protein of unknown function. Here we show that all three proteins bind lipids, in particular phosphatidic acid (PtdOH), which is known to participate in intracellular stress signaling. Genes encoding these proteins are expressed in the vasculature, a prerequisite for phloem transport. Cellular localization studies show that the proteins are not retained in the endoplasmic reticulum but surround the cell in a spotted pattern that has been previously observed with receptors and plasmodesmatal proteins. Abiotic signals that induce the production of PtdOH also regulate the expression of GDSL-lipase and PLAFP, albeit in opposite patterns. Our findings suggest that while all

Phloem proteomics reveals new lipid-binding proteins with a putative role in lipid-mediated signaling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbaglia, Allison M.; Tamot, Banita; Greve, Veronica

Global climate changes inversely affect our ability to grow the food required for an increasing world population. To combat future crop loss due to abiotic stress, we need to understand the signals responsible for changes in plant development and the resulting adaptations, especially the signaling molecules traveling long-distance through the plant phloem. Using a proteomics approach, we had identified several putative lipid-binding proteins in the phloem exudates. Simultaneously, we identified several complex lipids as well as jasmonates. These findings prompted us to propose that phloem (phospho-) lipids could act as long-distance developmental signals in response to abiotic stress, and thatmore » they are released, sensed, and moved by phloem lipid-binding proteins (Benning et al., 2012). Indeed, the proteins we identified include lipases that could release a signaling lipid into the phloem, putative receptor components, and proteins that could mediate lipid-movement. To test this possible protein-based lipid-signaling pathway, three of the proteins, which could potentially act in a relay, are characterized here: (I) a putative GDSL-motif lipase (II) a PIG-P-like protein, with a possible receptor-like function; (III) and PLAFP (phloem lipid-associated family protein), a predicted lipid-binding protein of unknown function. Here we show that all three proteins bind lipids, in particular phosphatidic acid (PtdOH), which is known to participate in intracellular stress signaling. Genes encoding these proteins are expressed in the vasculature, a prerequisite for phloem transport. Cellular localization studies show that the proteins are not retained in the endoplasmic reticulum but surround the cell in a spotted pattern that has been previously observed with receptors and plasmodesmatal proteins. Abiotic signals that induce the production of PtdOH also regulate the expression of GDSL-lipase and PLAFP, albeit in opposite patterns. Our findings suggest that while all

Insights into the complex association of bovine factor Va with acidic-lipid-containing synthetic membranes.

PubMed Central

Cutsforth, G A; Koppaka, V; Krishnaswamy, S; Wu, J R; Mann, K G; Lentz, B R

1996-01-01

The mechanism of binding of blood coagulation cofactor factor Va to acidic-lipid-containing membranes has been addressed. Binding isotherms were generated at room temperature using the change in fluorescence anisotropy of pyrene-labeled bovine factor Va to detect binding to sonicated membrane vesicles containing either bovine brain phosphatidylserine (PS) or 1,2-dioleoyl-3-sn-phosphatidylglycerol (DOPG) in combination with 1-palmitoyl-2-oleoyl-3-sn-phosphatidylcholine (POPC). The composition of the membranes was varied from 0 to 40 mol% for PS/POPC and from 0 to 65 mol % for DOPG/POPC membranes. Fitting the data to a classical Langmuir adsorption model yielded estimates of the dissociation constant (Kd) and the stoichiometry of binding. The values of Kd defined in this way displayed a maximum at low acidic lipid content but were nearly constant at intermediate to high fractions of acidic lipid. Fitting the binding isotherms to a two-process binding model (nonspecific adsorption in addition to binding of acidic lipids to sites on the protein) suggested a significant acidic-lipid-independent binding affinity in addition to occupancy of three protein sites that bind PS in preference to DOPG. Both analyses indicated that interaction of factor Va with an acidic-lipid-containing membrane is much more complex than those of factor Xa or prothrombin. Furthermore, a change in the conformation of bound pyrene-labeled factor Va with surface concentration of acidic lipid was implied by variation of both the saturating fluorescence anisotropy and the binding parameters with the acidic lipid content of the membrane. Finally, the results cannot support the contention that binding occurs through nonspecific adsorption to a patch or domain of acidic lipids in the membrane. Factor Va is suggested to associate with membranes by a complex process that includes both acidic-lipid-specific and acidic-lipid-independent sites and a protein structure change induced by occupancy of acidic-lipid

Protein-Lipid Interactions and Mechanisms of Antioxidant Activity of Proteins.

DTIC Science & Technology

1984-06-25

lysozyme and peroxidizing methyl fatty acid esters 3 F.~~~ ~ ~ -: 7 7-7777- 77.:1 71 7: .and decreases lipid hydroperoxide and malonadelhyde...freeze-dried emulsions of methyl linoleate with chicken egg lysozyme and other proteins, and in solution with amino acids and several aldehydes. Generation...4 Z,. ..- : , , , , . .:: . . ,.. -. , . . . .b - ? . Egg lecithin liposomes with hen- egg lysozyme localized either inside or outside the vesicles

Characteristic lipids of Bordetella pertussis: simple fatty acid composition, hydroxy fatty acids, and an ornithine-containing lipid.

PubMed Central

Kawai, Y; Moribayashi, A

1982-01-01

The lipids and fatty acids of Bordetella pertussis (phases I to IV) were analyzed by thin-layer chromatography, gas-liquid chromatography, and mass spectrometry and compared with those of B. parapertussis and B. bronchiseptica. The major lipid components of the three species were phosphatidylethanolamine, cardiolipin, phosphatidylglycerol, lysophosphatidylethanolamine, and an ornithine-containing lipid. The ornithine-containing lipid was characteristic of the genus Bordetella. The fatty acid composition of the total extractable cellular lipids of B. pertussis was mostly hexadecanoic and hexadecenoic acids (90%) in a ratio of about 1:1. The hexadecenoic acid of B. pertussis was in the cis-9 form. The fatty acid composition of the residual bound lipids was distinctly different from that of the extractable lipids, and residual bound lipids being mainly 3-hydroxytetradecanoic, tetradecanoic, and 3-hydroxydecanoic acids, with 3-hydroxydodecanoic acid occurring in some strains. It was determined that the 3-hydroxy fatty acids were derived from lipid A. The fatty acid composition of the total extractable cellular lipids of B. parapertussis and B. bronchiseptica, mainly composed of hexadecanoic and heptadecacyclopropanoic acid, differed from that of B. pertussis. Although the fatty acid composition of the residual bound lipids of B. parapertussis was similar to that of the residual bound lipids of B. pertussis, 2-hydroxydodecanoic acid was detected only in the bound lipids of B. bronchiseptica. Images PMID:6284719

Characteristic lipids of Bordetella pertussis: simple fatty acid composition, hydroxy fatty acids, and an ornithine-containing lipid.

PubMed

Kawai, Y; Moribayashi, A

1982-08-01

The lipids and fatty acids of Bordetella pertussis (phases I to IV) were analyzed by thin-layer chromatography, gas-liquid chromatography, and mass spectrometry and compared with those of B. parapertussis and B. bronchiseptica. The major lipid components of the three species were phosphatidylethanolamine, cardiolipin, phosphatidylglycerol, lysophosphatidylethanolamine, and an ornithine-containing lipid. The ornithine-containing lipid was characteristic of the genus Bordetella. The fatty acid composition of the total extractable cellular lipids of B. pertussis was mostly hexadecanoic and hexadecenoic acids (90%) in a ratio of about 1:1. The hexadecenoic acid of B. pertussis was in the cis-9 form. The fatty acid composition of the residual bound lipids was distinctly different from that of the extractable lipids, and residual bound lipids being mainly 3-hydroxytetradecanoic, tetradecanoic, and 3-hydroxydecanoic acids, with 3-hydroxydodecanoic acid occurring in some strains. It was determined that the 3-hydroxy fatty acids were derived from lipid A. The fatty acid composition of the total extractable cellular lipids of B. parapertussis and B. bronchiseptica, mainly composed of hexadecanoic and heptadecacyclopropanoic acid, differed from that of B. pertussis. Although the fatty acid composition of the residual bound lipids of B. parapertussis was similar to that of the residual bound lipids of B. pertussis, 2-hydroxydodecanoic acid was detected only in the bound lipids of B. bronchiseptica.

Improved Experimental Techniques for Analyzing Nucleic Acid Transport Through Protein Nanopores in Planar Lipid Bilayers

NASA Astrophysics Data System (ADS)

Costa, Justin A.

The translocation of nucleic acid polymers across cell membranes is a fundamental requirement for complex life and has greatly contributed to genomic molecular evolution. The diversity of pathways that have evolved to transport DNA and RNA across membranes include protein receptors, active and passive transporters, endocytic and pinocytic processes, and various types of nucleic acid conducting channels known as nanopores. We have developed a series of experimental techniques, collectively known as "Wicking", that greatly improves the biophysical analysis of nucleic acid transport through protein nanopores in planar lipid bilayers. We have verified the Wicking method using numerous types of classical ion channels including the well-studied chloride selective channel, CLIC1. We used the Wicking technique to reconstitute α-hemolysin and found that DNA translocation events of types A and B could be routinely observed using this method. Furthermore, measurable differences were observed in the duration of blockade events as DNA length and composition was varied, consistent with previous reports. Finally, we tested the ability of the Wicking technology to reconstitute the dsRNA transporter Sid-1. Exposure to dsRNAs of increasing length and complexity showed measurable differences in the current transitions suggesting that the charge carrier was dsRNA. However, the translocation events occurred so infrequently that a meaningful electrophysiological analysis was not possible. Alterations in the lipid composition of the bilayer had a minor effect on the frequency of translocation events but not to such a degree as to permit rigorous statistical analysis. We conclude that in many instances the Wicking method is a significant improvement to the lipid bilayer technique, but is not an optimal method for analyzing transport through Sid-1. Further refinements to the Wicking method might have future applications in high throughput DNA sequencing, DNA computation, and

Effect of olive leaf (Olea europea L.) extracts on protein and lipid oxidation of long-term frozen n-3 fatty acids-enriched pork patties.

PubMed

Botsoglou, Evropi; Govaris, Alexander; Ambrosiadis, Ioannis; Fletouris, Dimitrios; Botsoglou, Nikolas

2014-10-01

Our previous study has demonstrated the protective effects of olive leaf extracts on the oxidation of pork patties from n-3 fatty acid-enriched meat during refrigerated storage. The target of the present study was to examine these effects during frozen storage. Results showed that frozen storage accelerated (P=0.05) both lipid and protein oxidation in pork patties, but an addition of olive leaf extract at 200mg gallic acid equivalent/kg improved sensory attributes by delaying oxidation of lipids (reduction (P=0.05) of conjugated dienes, hydroperoxides and malondialdehyde), and of proteins (reduction (P=0.05) of protein carbonyls and inhibition (P=0.05) of the decrease of protein sulfhydryls). Copyright © 2014. Published by Elsevier Ltd.

Changes of Protein and Lipid Contents, Amino Acid and Fatty Acid Compositions in Eggs and Yolk-Sac Larvae of American Shad ( Alosa sapidissima)

NASA Astrophysics Data System (ADS)

Liu, Zhifeng; Gao, Xiaoqiang; Yu, Jiuxiang; Wang, Yaohui; Guo, Zhenglong; Huang, Bin; Liu, Baoliang; Hong, Lei

2018-04-01

To investigate the changes of the biochemical composition of American shad ( Alosa sapidissima) eggs and larvae at embryonic and early larval stages, samples were collected at different development stages from artificial fertilization to the end of yolk absorption including 2 h, 12 h and 30 h after fertilization and newly hatched larvae including 1 and 3 days after hatching. The composition of lipid, fatty acids, protein and amino acids were analyzed. The content of total protein exhibited a decreasing trend during embryogenesis and larval development, and a significant reduction was detected after hatching ( P < 0.05). The total lipid content remained relative stable. A significant reduction was detected in almost all amino acids after hatching except for glycine ( P < 0.05), while a significant decrease was found in the content of cysteine, proline, tyrosine, valine, isoleucine, leucine and phenylalanine during the yolk-sac phase ( P < 0.05). On the other hand, all the groups of fatty acids remained stable during the period of embryogenesis. But after hatching, a significant decrease was found in the content of C18:2n-6, C18:3n-6, SFA and ratio of EPA/ARA ( P < 0.05), while a significant increase was found in the content of C18:3n-3, C20:4n-6, C22:6n-3 and ratio of n-3/n-6 ( P < 0.05). In conclusion, the combined data suggested that American shad utilizes the protein content as preferential energy substrates during embryonic and early larval developments with some specificity in the consumption of different amino acids.

Effect of Lipid-Based Nanostructure on Protein Encapsulation within the Membrane Bilayer Mimetic Lipidic Cubic Phase Using Transmembrane and Lipo-proteins from the Beta-Barrel Assembly Machinery.

PubMed

van 't Hag, Leonie; Shen, Hsin-Hui; Lin, Tsung-Wu; Gras, Sally L; Drummond, Calum J; Conn, Charlotte E

2016-11-29

A fundamental understanding of the effect of amphiphilic protein encapsulation on the nanostructure of the bicontinuous cubic phase is crucial to progressing biomedical and biological applications of these hybrid protein-lipid materials, including as drug delivery vehicles, as biosensors, biofuel cells and for in meso crystallization. The relationship between the lipid nanomaterial and the encapsulated protein, however, remains poorly understood. In this study, we investigated the effect of incorporating the five transmembrane and lipo-proteins which make up the β-barrel assembly machinery from Gram-negative bacteria within a series of bicontinuous cubic phases. The transmembrane β-barrel BamA caused an increase in lattice parameter of the cubic phase upon encapsulation. By contrast, the mainly hydrophilic lipo-proteins BamB-E caused the cubic phase lattice parameters to decrease, despite their large size relative to the diameter of the cubic phase water channels. Analysis of the primary amino acid sequence was used to rationalize this effect, based on specific interactions between aromatic amino acids within the proteins and the polar-apolar interface. Other factors that were found to have an effect were lateral bilayer pressure and rigidity within the lipid bilayer, water channel diameter, and size and structure of the lipo-proteins. The data presented suggest that hydrophilic bioactive molecules can be selectively encapsulated within the cubic phase by using a lipid anchor or aromatic amino acids, for drug delivery or biosensing applications.

Counteracting foaming caused by lipids or proteins in biogas reactors using rapeseed oil or oleic acid as antifoaming agents.

PubMed

Kougias, P G; Boe, K; Einarsdottir, E S; Angelidaki, I

2015-08-01

Foaming is one of the major operational problems in biogas plants, and dealing with foaming incidents is still based on empirical practices. Various types of antifoams are used arbitrarily to combat foaming in biogas plants, but without any scientific support this action can lead to serious deterioration of the methanogenic process. Many commercial antifoams are derivatives of fatty acids or oils. However, it is well known that lipids can induce foaming in manure based biogas plants. This study aimed to elucidate the effect of rapeseed oil and oleic acid on foam reduction and process performance in biogas reactors fed with protein or lipid rich substrates. The results showed that both antifoams efficiently suppressed foaming. Moreover rapeseed oil resulted in stimulation of the biogas production. Finally, it was reckoned that the chemical structure of lipids, and more specifically their carboxylic ends, is responsible for their foam promoting or foam counteracting behaviour. Thus, it was concluded that the fatty acids and oils could suppress foaming, while salt of fatty acids could generate foam. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hypolipidemic effect of dietary pea proteins: Impact on genes regulating hepatic lipid metabolism.

PubMed

Rigamonti, Elena; Parolini, Cinzia; Marchesi, Marta; Diani, Erika; Brambilla, Stefano; Sirtori, Cesare R; Chiesa, Giulia

2010-05-01

Controversial data on the lipid-lowering effect of dietary pea proteins have been provided and the mechanisms behind this effect are not completely understood. The aim of the study was to evaluate a possible hypolipidemic activity of a pea protein isolate and to determine whether pea proteins could affect the hepatic lipid metabolism through regulation of genes involved in cholesterol and fatty acid homeostasis. Rats were fed Nath's hypercholesterolemic diets for 28 days, the protein sources being casein or a pea protein isolate from Pisum sativum. After 14 and 28 days of dietary treatment, rats fed pea proteins had markedly lower plasma cholesterol and triglyceride levels than rats fed casein (p<0.05). Pea protein-fed rats displayed higher hepatic mRNA levels of LDL receptor versus those fed casein (p<0.05). Hepatic mRNA concentration of genes involved in fatty acids synthesis, such as fatty acid synthase and stearoyl-CoA desaturase, was lower in pea protein-fed rats than in rats fed casein (p<0.05). In conclusion, the present study demonstrates a marked cholesterol and triglyceride-lowering activity of pea proteins in rats. Moreover, pea proteins appear to affect cellular lipid homeostasis by upregulating genes involved in hepatic cholesterol uptake and by downregulating fatty acid synthesis genes.

Lipids and topological rules of membrane protein assembly: balance between long and short range lipid-protein interactions.

PubMed

Vitrac, Heidi; Bogdanov, Mikhail; Heacock, Phil; Dowhan, William

2011-04-29

The N-terminal six-transmembrane domain (TM) bundle of lactose permease of Escherichia coli is uniformly inverted when assembled in membranes lacking phosphatidylethanolamine (PE). Inversion is dependent on the net charge of cytoplasmically exposed protein domains containing positive and negative residues, net charge of the membrane surface, and low hydrophobicity of TM VII acting as a molecular hinge between the two halves of lactose permease (Bogdanov, M., Xie, J., Heacock, P., and Dowhan, W. (2008) J. Cell Biol. 182, 925-935). Net neutral lipids suppress the membrane translocation potential of negatively charged amino acids, thus increasing the cytoplasmic retention potential of positively charged amino acids. Herein, TM organization of sucrose permease (CscB) and phenylalanine permease (PheP) as a function of membrane lipid composition was investigated to extend these principles to other proteins. For CscB, topological dependence on PE only becomes evident after a significant increase in the net negative charge of the cytoplasmic surface of the N-terminal TM bundle. High negative charge is required to overcome the thermodynamic block to inversion due to the high hydrophobicity of TM VII. Increasing the positive charge of the cytoplasmic surface of the N-terminal TM hairpin of PheP, which is misoriented in PE-lacking cells, favors native orientation in the absence of PE. PheP and CscB also display co-existing dual topologies dependent on changes in the charge balance between protein domains and the membrane lipids. Therefore, the topology of both permeases is dependent on PE. However, CscB topology is governed by thermodynamic balance between opposing lipid-dependent electrostatic and hydrophobic interactions.

Effect of olive leaf (Olea europea L.) extracts on protein and lipid oxidation in cooked pork meat patties enriched with n-3 fatty acids.

PubMed

Botsoglou, Evropi; Govaris, Alexandros; Ambrosiadis, Ioannis; Fletouris, Dimitrios; Papageorgiou, Georgios

2014-01-30

The effect of olive leaf extracts on lipid and protein oxidation of cooked pork patties refrigerated stored for 9 days was evaluated. Patties were prepared from longissimus dorsi muscle of pigs, and dietary supplemented with linseed oil. Results showed that dietary linseed oil modified the fatty acid composition of pork patties by increasing (P ≤ 0.05) n-3 (α-linolenic acid) and decreasing (P ≤ 0.05) n-6 (linoleic acid) fatty acids. Olive leaf extracts at supplementation levels of 200 and, especially, of 300 mg gallic acid equivalents kg⁻¹ meat, delayed lipid oxidation by reducing (P ≤ 0.05) both primary (conjugated dienes and hydroperoxides) and secondary (malondialdehyde) oxidation products. They also inhibited protein oxidation in a concentration-dependent manner by reducing (P ≤ 0.05) protein carbonyls and increasing (P ≤ 0.05) protein sulfhydryls. In addition, they improved sensory attributes of the n-3 enriched patties. Results suggested that olive leaf extracts might be useful to the meat industry as an efficient alternative to synthetic antioxidants. © 2013 Society of Chemical Industry.

Echinococcus granulosus fatty acid binding proteins subcellular localization.

PubMed

Alvite, Gabriela; Esteves, Adriana

2016-05-01

Two fatty acid binding proteins, EgFABP1 and EgFABP2, were isolated from the parasitic platyhelminth Echinococcus granulosus. These proteins bind fatty acids and have particular relevance in flatworms since de novo fatty acids synthesis is absent. Therefore platyhelminthes depend on the capture and intracellular distribution of host's lipids and fatty acid binding proteins could participate in lipid distribution. To elucidate EgFABP's roles, we investigated their intracellular distribution in the larval stage by a proteomic approach. Our results demonstrated the presence of EgFABP1 isoforms in cytosolic, nuclear, mitochondrial and microsomal fractions, suggesting that these molecules could be involved in several cellular processes. Copyright © 2016 Elsevier Inc. All rights reserved.

Down-regulation of lipid raft-associated onco-proteins via cholesterol-dependent lipid raft internalization in docosahexaenoic acid-induced apoptosis.

PubMed

Lee, Eun Jeong; Yun, Un-Jung; Koo, Kyung Hee; Sung, Jee Young; Shim, Jaegal; Ye, Sang-Kyu; Hong, Kyeong-Man; Kim, Yong-Nyun

2014-01-01

Lipid rafts, plasma membrane microdomains, are important for cell survival signaling and cholesterol is a critical lipid component for lipid raft integrity and function. DHA is known to have poor affinity for cholesterol and it influences lipid rafts. Here, we investigated a mechanism underlying the anti-cancer effects of DHA using a human breast cancer cell line, MDA-MB-231. We found that DHA decreased cell surface levels of lipid rafts via their internalization, which was partially reversed by cholesterol addition. With DHA treatment, caveolin-1, a marker for rafts, and EGFR were colocalized with LAMP-1, a lysosomal marker, in a cholesterol-dependent manner, indicating that DHA induces raft fusion with lysosomes. DHA not only displaced several raft-associated onco-proteins, including EGFR, Hsp90, Akt, and Src, from the rafts but also decreased total levels of those proteins via multiple pathways, including the proteasomal and lysosomal pathways, thereby decreasing their activities. Hsp90 overexpression maintained its client proteins, EGFR and Akt, and attenuated DHA-induced cell death. In addition, overexpression of Akt or constitutively active Akt attenuated DHA-induced apoptosis. All these data indicate that the anti-proliferative effect of DHA is mediated by targeting of lipid rafts via decreasing cell surface lipid rafts by their internalization, thereby decreasing raft-associated onco-proteins via proteasomal and lysosomal pathways and decreasing Hsp90 chaperone function. © 2013.

Chemical composition, mineral content and amino acid and lipid profiles in bones from various fish species.

PubMed

Toppe, Jogeir; Albrektsen, Sissel; Hope, Britt; Aksnes, Anders

2007-03-01

The chemical composition, content of minerals and the profiles of amino acids and fatty acids were analyzed in fish bones from eight different species of fish. Fish bones varied significantly in chemical composition. The main difference was lipid content ranging from 23 g/kg in cod (Gadus morhua) to 509 g/kg in mackerel (Scomber scombrus). In general fatty fish species showed higher lipid levels in the bones compared to lean fish species. Similarly, lower levels of protein and ash were observed in bones from fatty fish species. Protein levels differed from 363 g/kg lipid free dry matter (dm) to 568 g/kg lipid free dm with a concomitant inverse difference in ash content. Ash to protein ratio differed from 0.78 to 1.71 with the lowest level in fish that naturally have highest swimming and physical activity. Saithe (Pollachius virens) and salmon (Salmo salar) were found to be significantly different in the levels of lipid, protein and ash, and ash/protein ratio in the bones. Only small differences were observed in the level of amino acids although species specific differences were observed. The levels of Ca and P in lipid free fish bones were about the same in all species analyzed. Fatty acid profile differed in relation to total lipid levels in the fish bones, but some minor differences between fish species were observed.

HIV replication enhances production of free fatty acids, low density lipoproteins and many key proteins involved in lipid metabolism: a proteomics study.

PubMed

Rasheed, Suraiya; Yan, Jasper S; Lau, Alex; Chan, Arvan S

2008-08-20

HIV-infected patients develop multiple metabolic abnormalities including insulin resistance, lipodystrophy and dyslipidemia. Although progression of these disorders has been associated with the use of various protease inhibitors and other antiretroviral drugs, HIV-infected individuals who have not received these treatments also develop lipid abnormalities albeit to a lesser extent. How HIV alters lipid metabolism in an infected cell and what molecular changes are affected through protein interaction pathways are not well-understood. Since many genetic, epigenetic, dietary and other factors influence lipid metabolism in vivo, we have chosen to study genome-wide changes in the proteomes of a human T-cell line before and after HIV infection in order to circumvent computational problems associated with multiple variables. Four separate experiments were conducted including one that compared 14 different time points over a period of >3 months. By subtractive analyses of protein profiles overtime, several hundred differentially expressed proteins were identified in HIV-infected cells by mass spectrometry and each protein was scrutinized for its biological functions by using various bioinformatics programs. Herein, we report 18 HIV-modulated proteins and their interaction pathways that enhance fatty acid synthesis, increase low density lipoproteins (triglycerides), dysregulate lipid transport, oxidize lipids, and alter cellular lipid metabolism. We conclude that HIV replication alone (i.e. without any influence of antiviral drugs, or other human genetic factors), can induce novel cellular enzymes and proteins that are significantly associated with biologically relevant processes involved in lipid synthesis, transport and metabolism (p = <0.0002-0.01). Translational and clinical studies on the newly discovered proteins may now shed light on how some of these proteins may be useful for early diagnosis of individuals who might be at high risk for developing lipid

Molecular Simulations of Sequence-Specific Association of Transmembrane Proteins in Lipid Bilayers

NASA Astrophysics Data System (ADS)

Doxastakis, Manolis; Prakash, Anupam; Janosi, Lorant

2011-03-01

Association of membrane proteins is central in material and information flow across the cellular membranes. Amino-acid sequence and the membrane environment are two critical factors controlling association, however, quantitative knowledge on such contributions is limited. In this work, we study the dimerization of helices in lipid bilayers using extensive parallel Monte Carlo simulations with recently developed algorithms. The dimerization of Glycophorin A is examined employing a coarse-grain model that retains a level of amino-acid specificity, in three different phospholipid bilayers. Association is driven by a balance of protein-protein and lipid-induced interactions with the latter playing a major role at short separations. Following a different approach, the effect of amino-acid sequence is studied using the four transmembrane domains of the epidermal growth factor receptor family in identical lipid environments. Detailed characterization of dimer formation and estimates of the free energy of association reveal that these helices present significant affinity to self-associate with certain dimers forming non-specific interfaces.

Fatty acid-binding protein 5 (FABP5) promotes lipolysis of lipid droplets, de novo fatty acid (FA) synthesis and activation of nuclear factor-kappa B (NF-κB) signaling in cancer cells.

PubMed

Senga, Shogo; Kobayashi, Narumi; Kawaguchi, Koichiro; Ando, Akira; Fujii, Hiroshi

2018-06-12

Fatty acid-binding proteins (FABPs) are involved in binding and storing hydrophobic ligands such as long-chain fatty acids, as well as transporting them to the appropriate compartments in the cell. Epidermal fatty acid-binding protein (FABP5) is an intracellular lipid-binding protein that is abundantly expressed in adipocytes and macrophages. Previous studies have revealed that the FABP5 expression level is closely related to malignancy in various types of cancer. However, its precise functions in the metabolisms of cancer cells remain unclear. Here, we revealed that FABP5 knockdown significantly induced downregulation of the genes expression, such as hormone-sensitive lipase (HSL), monoacylglycerol lipase (MAGL), elongation of long-chain fatty acid member 6 (Elovl6), and acyl-CoA synthetase long-chain family member 1 (ACSL1), which are involved in altered lipid metabolism, lipolysis, and de novo FA synthesis in highly aggressive prostate and breast cancer cells. Moreover, we demonstrated that FABP5 induced inflammation and cytokine production through the nuclear factor-kappa B signaling pathway activated by reactive oxygen species and protein kinase C in PC-3 and MDA-MB-231 cells. Thus, FABP5 might regulate lipid quality and/or quantity to promote aggressiveness such as cell growth, invasiveness, survival, and inflammation in prostate and breast cancer cells. In the present study, we have revealed for the first time that high expression of FABP5 plays a critical role in alterations of lipid metabolism, leading to cancer development and metastasis in highly aggressive prostate and breast cancer cells. Copyright © 2018. Published by Elsevier B.V.

Lipid transport mediated by Arabidopsis TGD proteins is unidirectional from the endoplasmic reticulum to the plastid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, C.; Moellering, E. R., Muthan, B.; Fan, J.

2010-06-01

The transfer of lipids between the endoplasmic reticulum (ER) and the plastid in Arabidopsis involves the TRIGALACTOSYLDIACYLGLYCEROL (TGD) proteins. Lipid exchange is thought to be bidirectional based on the presence of specific lipid molecular species in Arabidopsis mutants impaired in the desaturation of fatty acids of membrane lipids in the ER and plastid. However, it was unclear whether TGD proteins were required for lipid trafficking in both directions. This question was addressed through the analysis of double mutants of tgd1-1 or tgd4-3 in genetic mutant backgrounds leading to a defect in lipid fatty acid desaturation either in the ER (fad2)more » or the plastid (fad6). The fad6 tgd1-1 and fad6 tgd4-3 double mutants showed drastic reductions in the relative levels of polyunsaturated fatty acids and of galactolipids. The growth of these plants and the development of photosynthetic membrane systems were severely compromised, suggesting a disruption in the import of polyunsaturated fatty acid-containing lipid species from the ER. Furthermore, a forward-genetic screen in the tgd1-2 dgd1 mutant background led to the isolation of a new fad6-2 allele with a marked reduction in the amount of digalactosyldiacylglycerol. In contrast, the introduction of fad2, affecting fatty acid desaturation of lipids in the ER, into the two tgd mutant backgrounds did not further decrease the level of fatty acid desaturation in lipids of extraplastidic membranes. These results suggest that the role of TGD proteins is limited to plastid lipid import, but does not extend to lipid export from the plastid to extraplastidic membranes.« less

Metformin reduces lipid accumulation in macrophages by inhibiting FOXO1-mediated transcription of fatty acid-binding protein 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Jun; Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX; Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, TX

2010-02-26

Objective: The accumulation of lipids in macrophages contributes to the development of atherosclerosis. Strategies to reduce lipid accumulation in macrophages may have therapeutic potential for preventing and treating atherosclerosis and cardiovascular complications. The antidiabetic drug metformin has been reported to reduce lipid accumulation in adipocytes. In this study, we examined the effects of metformin on lipid accumulation in macrophages and investigated the mechanisms involved. Methods and results: We observed that metformin significantly reduced palmitic acid (PA)-induced intracellular lipid accumulation in macrophages. Metformin promoted the expression of carnitine palmitoyltransferase I (CPT-1), while reduced the expression of fatty acid-binding protein 4 (FABP4)more » which was involved in PA-induced lipid accumulation. Quantitative real-time PCR showed that metformin regulates FABP4 expression at the transcriptional level. We identified forkhead transcription factor FOXO1 as a positive regulator of FABP4 expression. Inhibiting FOXO1 expression with FOXO1 siRNA significantly reduced basal and PA-induced FABP4 expression. Overexpression of wild-type FOXO1 and constitutively active FOXO1 significantly increased FABP4 expression, whereas dominant negative FOXO1 dramatically decreased FABP4 expression. Metformin reduced FABP4 expression by promoting FOXO1 nuclear exclusion and subsequently inhibiting its activity. Conclusions: Taken together, these results suggest that metformin reduces lipid accumulation in macrophages by repressing FOXO1-mediated FABP4 transcription. Thus, metformin may have a protective effect against lipid accumulation in macrophages and may serve as a therapeutic agent for preventing and treating atherosclerosis in metabolic syndrome.« less

Molecular simulations of lipid-mediated protein-protein interactions.

PubMed

de Meyer, Frédérick Jean-Marie; Venturoli, Maddalena; Smit, Berend

2008-08-01

Recent experimental results revealed that lipid-mediated interactions due to hydrophobic forces may be important in determining the protein topology after insertion in the membrane, in regulating the protein activity, in protein aggregation and in signal transduction. To gain insight into the lipid-mediated interactions between two intrinsic membrane proteins, we developed a mesoscopic model of a lipid bilayer with embedded proteins, which we studied with dissipative particle dynamics. Our calculations of the potential of mean force between transmembrane proteins show that hydrophobic forces drive long-range protein-protein interactions and that the nature of these interactions depends on the length of the protein hydrophobic segment, on the three-dimensional structure of the protein and on the properties of the lipid bilayer. To understand the nature of the computed potentials of mean force, the concept of hydrophilic shielding is introduced. The observed protein interactions are interpreted as resulting from the dynamic reorganization of the system to maintain an optimal hydrophilic shielding of the protein and lipid hydrophobic parts, within the constraint of the flexibility of the components. Our results could lead to a better understanding of several membrane processes in which protein interactions are involved.

Selective fermentation of carbohydrate and protein fractions of Scenedesmus, and biohydrogenation of its lipid fraction for enhanced recovery of saturated fatty acids.

PubMed

Lai, YenJung Sean; Parameswaran, Prathap; Li, Ang; Aguinaga, Alyssa; Rittmann, Bruce E

2016-02-01

Biofuels derived from microalgae have promise as carbon-neutral replacements for petroleum. However, difficulty extracting microalgae-derived lipids and the co-extraction of non-lipid components add major costs that detract from the benefits of microalgae-based biofuel. Selective fermentation could alleviate these problems by managing microbial degradation so that carbohydrates and proteins are hydrolyzed and fermented, but lipids remain intact. We evaluated selective fermentation of Scenedesmus biomass in batch experiments buffered at pH 5.5, 7, or 9. Carbohydrates were fermented up to 45% within the first 6 days, protein fermentation followed after about 20 days, and lipids (measured as fatty acid methyl esters, FAME) were conserved. Fermentation of the non-lipid components generated volatile fatty acids, with acetate, butyrate, and propionate being the dominant products. Selective fermentation of Scenedesmus biomass increased the amount of extractable FAME and the ratio of FAME to crude lipids. It also led to biohydrogenation of unsaturated FAME to more desirable saturated FAME (especially to C16:0 and C18:0), and the degree of saturation was inversely related to the accumulation of hydrogen gas after fermentation. Moreover, the microbial communities after selective fermentation were enriched in bacteria from families known to perform biohydrogenation, i.e., Porphyromonadaceae and Ruminococcaceae. Thus, this study provides proof-of-concept that selective fermentation can improve the quantity and quality of lipids that can be extracted from Scenedesmus. © 2015 Wiley Periodicals, Inc.

Expression of Lipid Metabolism-Related Proteins in Metastatic Breast Cancer.

PubMed

Jung, Yoon Yang; Kim, Hye Min; Koo, Ja Seung

2015-01-01

The tumor biology of metastatic breast cancers differ according to the metastatic sites, and the features of cancer metabolism may also be different. The aim of this study is to investigate the expression of lipid metabolism-related proteins in metastatic breast cancer according to metastatic site and discuss the clinical significance thereof. Immunohistochemical staining for lipid metabolism-related proteins [fatty acid synthase (FASN), hormone-sensitive lipase (HSL), carnitine palmitoyltransferase IA (CPT-1A), acyl-CoA oxidase 1 (ACOX1), fatty acid binding protein 4 (FABP4,) and perilipin 1 (PLIN1)] was performed using a tissue microarray of 149 cases of metastatic breast cancer (bone metastasis = 39, brain metastasis = 37, liver metastasis = 21, and lung metastasis = 52). The expression levels of ACOX1 (p = 0.009) and FASN (p = 0.007) varied significantly according to metastatic site, with the highest expression in brain metastasis and the lowest expression in liver metastasis. ACOX1 positivity (p = 0.005) and FASN positivity (p = 0.003) correlated with HER-2 positivity. The expression of FASN was significantly higher in HER-2 type breast cancer, and lower in luminal A and TNBC type breast cancer (p<0.001). Among lipid metabolism-related proteins, PLIN1 positivity was found to be an independent poor prognostic factor on multivariate analysis (Hazard ratio: 4.979, 95% CI: 1.054-22.59, p = 0.043). Different expression levels of lipid metabolism-related proteins were observed according to metastatic site. The expression of ACOX1 and FASN was highest in brain metastasis. These results suggest that the metastatic site should be considered when using lipid metabolism inhibitors for targeted therapy.

Overexpression of heart-type fatty acid binding protein enhances fatty acid-induced podocyte injury.

PubMed

Gao, Qing; Sarkar, Alhossain; Chen, Yizhi; Xu, Bo; Zhu, Xiaojuan; Yuan, Yang; Guan, Tianjun

2018-02-01

Deregulated lipid metabolism is a characteristic of metabolic diseases including type 2 diabetes and obesity, and likely contributes to podocyte injury and end-stage kidney disease. Heart-type fatty acid binding protein (H-FABP) was reported to be associated with lipid metabolism. The present study investigated whether H-FABP contributes to podocyte homeostasis. Podocytes were transfected by lentiviral vector to construct a cell line which stably overexpressed H-FABP. Small interfering RNA capable of effectively silencing H-FABP was introduced into podocytes to construct a cell line with H-FABP knockdown. Certain groups were treated with palmitic acid (PA) and the fat metabolism, as well as inflammatory and oxidative stress markers were measured. PA accelerated lipid metabolism derangement, inflammatory reaction and oxidative stress in podocytes. Overexpression of H-FABP enhanced the PA-induced disequilibrium in podocytes. The mRNA and protein expression levels of acyl-coenzyme A oxidase 3 and monocyte chemotactic protein 1, and the protein expression levels of 8-hydroxy-2'-deoxyguanosine and 4-hydroxynonenal were upregulated in the H-FABP overexpression group, while the mRNA and protein expression of peroxisome proliferator activated receptor α was downregulated. Knockdown of H-FABP inhibited the PA-induced injury and lipid metabolism derangement, as well as the inflammatory reaction and oxidative stress in podocytes. These results indicated that overexpression of H-FABP enhances fatty acid-induced podocyte injury, while H-FABP inhibition may represent a potential therapeutic strategy for the prevention of lipid metabolism-associated podocyte injury.

Identification of Protein Targets of 12/15-Lipoxygenase-Derived Lipid Electrophiles in Mouse Peritoneal Macrophages Using Omega-Alkynyl Fatty Acid.

PubMed

Isobe, Yosuke; Kawashima, Yusuke; Ishihara, Tomoaki; Watanabe, Kenji; Ohara, Osamu; Arita, Makoto

2018-04-20

The 12/15-lipoxygenase (12/15-LOX) enzyme introduces peroxyl groups, in a position-specific manner, into polyunsaturated fatty acids to form various kinds of bioactive lipid metabolites, including lipid-derived electrophiles (LDE). The resident peritoneal macrophage is the site of highest 12/15-LOX expression in the mouse. However, the role of the enzyme in the regulation of resident macrophages is not fully understood. Here, we describe a chemoproteomic method to identify the targets of enzymatically generated LDE. By treating mouse peritoneal macrophages with omega-alkynyl arachidonic acid (aAA), we identified a series of proteins adducted by LDE generated through a 12/15-LOX catalyzed reaction. Pathway analysis revealed a dramatic enrichment of proteins involved in energy metabolism and found that glycolytic flux and mitochondrial respiration were significantly affected by the expression of 12/15-LOX. Our findings thus highlight the utility of chemoproteomics using aAA for identifying intracellular targets of enzymatically generated LDE.

A new lipid carrier protein in the cattle tick Rhipicephalus microplus.

PubMed

Kluck, George E G; Silva Cardoso, Lívia; De Cicco, Nuccia N T; Lima, Michele S; Folly, Evelize; Atella, Georgia C

2018-05-01

Tick infestation in cattle reflects the main cause of economic loss to cattle producers. This is due to several reasons but mainly to their ability to feed on blood and generate a huge amount of eggs. Lipid transport in arthropods is achieved by highly specialized hemolymphatic lipoproteins, which resemble those described in vertebrate blood. Such lipoproteins continuously deliver lipids through the blood to growing eggs. The injection of radioactive [ 3 H] palmitic acid into tick hemocoel showed that the gut, ovary, fat body and Gene's organ were the main organs of incorporation of this labeled fatty acid. The rate of [ 3 H] palmitic acid incorporation by the organs was high up to 30 min after injection. The [ 3 H] palmitic acid incorporated by these organs was later found in phospholipids and neutral lipids. Here, we describe the purification and characterization of a key player of lipid dynamics in tick hemolymph. The Rhipicephalus microplus lipid-apolipoprotein complex (RmLCP) is a new high-density lipoprotein (1.18 g/mL), which accounts for over 90% of [ 3 H] palmitic acid present in the hemolymph. It has a native molecular weight of 420 kDa and is composed of one subunit of 122 kDa. Protein identification analysis of RmLPC subunit showed two better hits: vitellogenin 2 (23% protein coverage) and vitellogenin 5 (29% protein coverage), respectively and similarities with hemolymphatic apolipoproteins of arachnids such as the tick Ixodes scapularis (80%), the mite Galendromus occidentalis (44%) and the spider Parasteatoda tepidariorum (43%) and also for the insects Locusta migratoria (45%), Drosophila melanogaster (42%) and Manduca sexta (47%) to vitellogenin 2 and tick Ixodes scapularis (83%), the crab Limulus polyphemus (55%) and the oyster Crassostrea gigas (55%) to vitellogenin 5. Furthermore, it shows a distinct lipid composition from most arthropod lipoproteins, being composed of 40% free cholesterol, 27% phospholipids, 20% triacylglycerol and 15

Lipid metabolism in response to individual short chain fatty acids during mixotrophic mode of microalgal cultivation: Influence on biodiesel saturation and protein profile.

PubMed

Chandra, Rashmi; Arora, Somya; Rohit, M V; Venkata Mohan, S

2015-01-01

Critical influence of different short chain fatty acids as organic carbon source, during growth (GP) and nutrient stress lipogenic phase (NSLP) was investigated on biomass and lipid productivity, in mixotrophic fed-batch microalgae cultivation. Nutrient deprivation induced physiological stress stimulated highest lipid productivity with acetate (total/neutral lipids, 35/17) with saturation index of 80.53% by the end of NSLP followed by butyrate (12/7%; 78%). Biomass growth followed the order of acetate (2.23 g/l) >butyrate (0.99 g/l) >propionate (0.77 g/l). VFA removal (as COD) was maximum with acetate (87%) followed by butyrate (55.09%) and propionate (10.60%). Palmitic acid was the most dominant fatty acid found in the fatty acid composition of all variants and butyrate fed system yielded a maximum of 44% palmitic acid. Protein profiling illustrated prominence of acetyl CoA-synthetase activity in acetate system. Thus, fatty acids provide a promising alternative feedstock for biodiesel production with integrated microalgae-biorefinery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Introduction to fatty acids and lipids.

PubMed

Burdge, Graham C; Calder, Philip C

2015-01-01

The purpose of this article is to describe the structure, function and metabolism of fatty acids and lipids that are of particular importance in the context of parenteral nutrition. Lipids are a heterogeneous group of molecules that share the common property of hydrophobicity. Lipids range in structure from simple short hydrocarbon chains to more complex molecules, including triacylglycerols, phospholipids and sterols and their esters. Lipids within each class may differ structurally. Fatty acids are common components of complex lipids, and these differ according to chain length and the presence, number and position of double bonds in the hydrocarbon chain. Structural variation among complex lipids and among fatty acids gives rise to functional differences that result in different impacts upon metabolism and upon cell and tissue responses. Fatty acids and complex lipids exhibit a variety of structural variations that influence their metabolism and their functional effects. © 2015 S. Karger AG, Basel.

Overexpression of heart-type fatty acid binding protein enhances fatty acid-induced podocyte injury

PubMed Central

Gao, Qing; Sarkar, Alhossain; Chen, Yizhi; Xu, Bo; Zhu, Xiaojuan; Yuan, Yang; Guan, Tianjun

2018-01-01

Deregulated lipid metabolism is a characteristic of metabolic diseases including type 2 diabetes and obesity, and likely contributes to podocyte injury and end-stage kidney disease. Heart-type fatty acid binding protein (H-FABP) was reported to be associated with lipid metabolism. The present study investigated whether H-FABP contributes to podocyte homeostasis. Podocytes were transfected by lentiviral vector to construct a cell line which stably overexpressed H-FABP. Small interfering RNA capable of effectively silencing H-FABP was introduced into podocytes to construct a cell line with H-FABP knockdown. Certain groups were treated with palmitic acid (PA) and the fat metabolism, as well as inflammatory and oxidative stress markers were measured. PA accelerated lipid metabolism derangement, inflammatory reaction and oxidative stress in podocytes. Overexpression of H-FABP enhanced the PA-induced disequilibrium in podocytes. The mRNA and protein expression levels of acyl-coenzyme A oxidase 3 and monocyte chemotactic protein 1, and the protein expression levels of 8-hydroxy-2′-deoxyguanosine and 4-hydroxynonenal were upregulated in the H-FABP overexpression group, while the mRNA and protein expression of peroxisome proliferator activated receptor α was downregulated. Knockdown of H-FABP inhibited the PA-induced injury and lipid metabolism derangement, as well as the inflammatory reaction and oxidative stress in podocytes. These results indicated that overexpression of H-FABP enhances fatty acid-induced podocyte injury, while H-FABP inhibition may represent a potential therapeutic strategy for the prevention of lipid metabolism-associated podocyte injury. PMID:29434805

Dynamic Lipid-dependent Modulation of Protein Topology by Post-translational Phosphorylation.

PubMed

Vitrac, Heidi; MacLean, David M; Karlstaedt, Anja; Taegtmeyer, Heinrich; Jayaraman, Vasanthi; Bogdanov, Mikhail; Dowhan, William

2017-02-03

Membrane protein topology and folding are governed by structural principles and topogenic signals that are recognized and decoded by the protein insertion and translocation machineries at the time of initial membrane insertion and folding. We previously demonstrated that the lipid environment is also a determinant of initial protein topology, which is dynamically responsive to post-assembly changes in membrane lipid composition. However, the effect on protein topology of post-assembly phosphorylation of amino acids localized within initially cytoplasmically oriented extramembrane domains has never been investigated. Here, we show in a controlled in vitro system that phosphorylation of a membrane protein can trigger a change in topological arrangement. The rate of change occurred on a scale of seconds, comparable with the rates observed upon changes in the protein lipid environment. The rate and extent of topological rearrangement were dependent on the charges of extramembrane domains and the lipid bilayer surface. Using model membranes mimicking the lipid compositions of eukaryotic organelles, we determined that anionic lipids, cholesterol, sphingomyelin, and membrane fluidity play critical roles in these processes. Our results demonstrate how post-translational modifications may influence membrane protein topology in a lipid-dependent manner, both along the organelle trafficking pathway and at their final destination. The results provide further evidence that membrane protein topology is dynamic, integrating for the first time the effect of changes in lipid composition and regulators of cellular processes. The discovery of a new topology regulatory mechanism opens additional avenues for understanding unexplored structure-function relationships and the development of optimized topology prediction tools. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Betaine and arginine supplementation of low protein diets improves plasma lipids but does not affect hepatic fatty acid composition and related gene expression profiling in pigs.

PubMed

Madeira, Marta S; Rolo, Eva A; Lopes, Paula A; Ramos, Denis A; Alfaia, Cristina M; Pires, Virgínia Mr; Martins, Susana V; Pinto, Rui Ma; Prates, José Am

2018-01-01

The individual and combined effects of betaine and arginine supplemented to reduced protein diets were investigated on plasma metabolites, hepatic fatty acid composition and mRNA levels of lipid-sensitive factors in commercial pigs. Betaine has previously been shown to reduce carcass fat deposition and arginine improves meat quality of finishing pigs. Forty male crossbred pigs were randomly assigned to one of five diets (n = 8): 160 g kg -1 of crude protein (NPD), 130 g kg -1 of crude protein (RPD), RPD with 3.3 g kg -1 of betaine, RPD with 15 g kg -1 of arginine, and RPD with 3.3 g kg -1 of betaine and 15 g kg -1 of arginine. The restriction of dietary protein increased total lipids (P < 0.001), total cholesterol (P < 0.001), high-density lipoprotein-cholesterol (P < 0.001) and low-density lipoprotein cholesterol (P < 0.001). Betaine and arginine, individually or combined, reduced the majority of plasma lipids (P < 0.05) without affecting total fatty acids in the liver and the overall gene expression pattern. These findings suggest a positive effect of betaine and arginine, singly or combined, by reversing plasma lipids increase promoted by dietary protein restriction. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Adipose differentiation-related protein regulates lipids and insulin in pancreatic islets

PubMed Central

Faleck, D. M.; Ali, K.; Roat, R.; Graham, M. J.; Crooke, R. M.; Battisti, R.; Garcia, E.; Ahima, R. S.

2010-01-01

The excess accumulation of lipids in islets is thought to contribute to the development of diabetes in obesity by impairing β-cell function. However, lipids also serve a nutrient function in islets, and fatty acids acutely increase insulin secretion. A better understanding of lipid metabolism in islets will shed light on complex effects of lipids on β-cells. Adipose differentiation-related protein (ADFP) is localized on the surface of lipid droplets in a wide range of cells and plays an important role in intracellular lipid metabolism. We found that ADFP was highly expressed in murine β-cells. Moreover, islet ADFP was increased in mice on a high-fat diet (3.5-fold of control) and after fasting (2.5-fold of control), revealing dynamic changes in ADFP in response to metabolic cues. ADFP expression was also increased by addition of fatty acids in human islets. The downregulation of ADFP in MIN6 cells by antisense oligonucleotide (ASO) suppressed the accumulation of triglycerides upon fatty acid loading (56% of control) along with a reduction in the mRNA levels of lipogenic genes such as diacylglycerol O-acyltransferase-2 and fatty acid synthase. Fatty acid uptake, oxidation, and lipolysis were also reduced by downregulation of ADFP. Moreover, the reduction of ADFP impaired the ability of palmitate to increase insulin secretion. These findings demonstrate that ADFP is important in regulation of lipid metabolism and insulin secretion in β-cells. PMID:20484013

Localization and Ordering of Lipids Around Aquaporin-0: Protein and Lipid Mobility Effects.

PubMed

Briones, Rodolfo; Aponte-Santamaría, Camilo; de Groot, Bert L

2017-01-01

Hydrophobic matching, lipid sorting, and protein oligomerization are key principles by which lipids and proteins organize in biological membranes. The Aquaporin-0 channel (AQP0), solved by electron crystallography (EC) at cryogenic temperatures, is one of the few protein-lipid complexes of which the structure is available in atomic detail. EC and room-temperature molecular dynamics (MD) of dimyristoylglycerophosphocholine (DMPC) annular lipids around AQP0 show similarities, however, crystal-packing and temperature might affect the protein surface or the lipids distribution. To understand the role of temperature, lipid phase, and protein mobility in the localization and ordering of AQP0-lipids, we used MD simulations of an AQP0-DMPC bilayer system. Simulations were performed at physiological and at DMPC gel-phase temperatures. To decouple the protein and lipid mobility effects, we induced gel-phase in the lipids or restrained the protein. We monitored the lipid ordering effects around the protein. Reducing the system temperature or inducing lipid gel-phase had a marginal effect on the annular lipid localization. However, restraining the protein mobility increased the annular lipid localization around the whole AQP0 surface, resembling EC. The distribution of the inter-phosphate and hydrophobic thicknesses showed that stretching of the DMPC annular layer around AQP0 surface is the mechanism that compensates the hydrophobic mismatch in this system. The distribution of the local area-per-lipid and the acyl-chain order parameters showed particular fluid- and gel-like areas that involved several lipid layers. These areas were in contact with the surfaces of higher and lower protein mobility, respectively. We conclude that the AQP0 surfaces induce specific fluid- and gel-phase prone areas. The presence of these areas might guide the AQP0 lipid sorting interactions with other membrane components, and is compatible with the squared array oligomerization of AQP0 tetramers

Chlorogenic acid from honeysuckle improves hepatic lipid dysregulation and modulates hepatic fatty acid composition in rats with chronic endotoxin infusion.

PubMed

Zhou, Yan; Ruan, Zheng; Wen, Yanmei; Yang, Yuhui; Mi, Shumei; Zhou, Lili; Wu, Xin; Ding, Sheng; Deng, Zeyuan; Wu, Guoyao; Yin, Yulong

2016-03-01

Chlorogenic acid as a natural hydroxycinnamic acid has protective effect for liver. Endotoxin induced metabolic disorder, such as lipid dysregulation and hyperlipidemia. In this study, we investigated the effect of chlorogenic acid in rats with chronic endotoxin infusion. The Sprague-Dawley rats with lipid metabolic disorder (LD group) were intraperitoneally injected endotoxin. And the rats of chlorogenic acid-LD group were daily received chlorogenic acid by intragastric administration. In chlorogenic acid-LD group, the area of visceral adipocyte was decreased and liver injury was ameliorated, as compared to LD group. In chlorogenic acid-LD group, serum triglycerides, free fatty acids, hepatic triglycerides and cholesterol were decreased, the proportion of C20:1, C24:1 and C18:3n-6, Δ9-18 and Δ6-desaturase activity index in the liver were decreased, and the proportion of C18:3n-3 acid was increased, compared to the LD group. Moreover, levels of phosphorylated AMP-activated protein kinase, carnitine palmitoyltransferase-I, and fatty acid β-oxidation were increased in chlorogenic acid-LD group compared to LD rats, whereas levels of fatty acid synthase and acetyl-CoA carboxylase were decreased. These findings demonstrate that chlorogenic acid effectively improves hepatic lipid dysregulation in rats by regulating fatty acid metabolism enzymes, stimulating AMP-activated protein kinase activation, and modulating levels of hepatic fatty acids.

Lipid and protein oxidation of α-linolenic acid-enriched pork during refrigerated storage as influenced by diet supplementation with olive leaves (Olea europea L.) or α-tocopheryl acetate.

PubMed

Botsoglou, Evropi; Govaris, Alexander; Ambrosiadis, Ioannis; Fletouris, Dimitrios

2012-12-01

The objective of this study was to evaluate the effect of diet supplementation with olive leaves or α-tocopheryl acetate on lipid and protein oxidation of raw and cooked n-3 enriched-pork during refrigerated storage. Enrichment of pork with α-linolenic acid through diet supplementation with linseed oil enhanced (p≤0.05) lipid oxidation in both raw and cooked chops but had no effect (p>0.05) on protein oxidation during refrigerated storage while decreasing (p≤0.05) the sensory attributes of cooked pork. Diet supplementation with olive leaves or α-tocopheryl acetate had no effect (p>0.05) on the fatty acid composition of pork but decreased (p≤0.05) lipid oxidation while exerting no effect (p>0.05) on protein oxidation in both raw and cooked α-linolenic acid-enriched chops stored and chilled for 9 days. Moreover, olive leaves and α-tocopheryl acetate supplemented at 10 g/kg and 200mg/kg diet, respectively, exerted (p≤0.05) a beneficial effect on the sensory attributes of cooked α-linolenic acid-enriched pork chops. Copyright © 2012 Elsevier Ltd. All rights reserved.

Combined nitrogen limitation and cadmium stress stimulate total carbohydrates, lipids, protein and amino acid accumulation in Chlorella vulgaris (Trebouxiophyceae).

PubMed

Chia, Mathias Ahii; Lombardi, Ana Teresa; da Graça Gama Melão, Maria; Parrish, Christopher C

2015-03-01

Metals have interactive effects on the uptake and metabolism of nutrients in microalgae. However, the effect of trace metal toxicity on amino acid composition of Chlorella vulgaris as a function of varying nitrogen concentrations is not known. In this research, C. vulgaris was used to investigate the influence of cadmium (10(-7) and 2.0×10(-8)molL(-1) Cd) under varying nitrogen (2.9×10(-6), 1.1×10(-5) and 1.1×10(-3)molL(-1)N) concentrations on its growth rate, biomass and biochemical composition. Total carbohydrates, total proteins, total lipids, as well as individual amino acid proportions were determined. The combination of Cd stress and N limitation significantly inhibited growth rate and cell density of C. vulgaris. However, increasing N limitation and Cd stress stimulated higher dry weight and chlorophyll a production per cell. Furthermore, biomolecules like total proteins, carbohydrates and lipids increased with increasing N limitation and Cd stress. Ketogenic and glucogenic amino acids were accumulated under the stress conditions investigated in the present study. Amino acids involved in metal chelation like proline, histidine and glutamine were significantly increased after exposure to combined Cd stress and N limitation. We conclude that N limitation and Cd stress affects the physiology of C. vulgaris by not only decreasing its growth but also stimulating biomolecule production. Copyright © 2015 Elsevier B.V. All rights reserved.

The simulation approach to lipid-protein interactions.

PubMed

Paramo, Teresa; Garzón, Diana; Holdbrook, Daniel A; Khalid, Syma; Bond, Peter J

2013-01-01

The interactions between lipids and proteins are crucial for a range of biological processes, from the folding and stability of membrane proteins to signaling and metabolism facilitated by lipid-binding proteins. However, high-resolution structural details concerning functional lipid/protein interactions are scarce due to barriers in both experimental isolation of native lipid-bound complexes and subsequent biophysical characterization. The molecular dynamics (MD) simulation approach provides a means to complement available structural data, yielding dynamic, structural, and thermodynamic data for a protein embedded within a physiologically realistic, modelled lipid environment. In this chapter, we provide a guide to current methods for setting up and running simulations of membrane proteins and soluble, lipid-binding proteins, using standard atomistically detailed representations, as well as simplified, coarse-grained models. In addition, we outline recent studies that illustrate the power of the simulation approach in the context of biologically relevant lipid/protein interactions.

FAX1, a Novel Membrane Protein Mediating Plastid Fatty Acid Export

PubMed Central

Li, Nannan; Gügel, Irene Luise; Giavalisco, Patrick; Zeisler, Viktoria; Schreiber, Lukas; Soll, Jürgen; Philippar, Katrin

2015-01-01

Fatty acid synthesis in plants occurs in plastids, and thus, export for subsequent acyl editing and lipid assembly in the cytosol and endoplasmatic reticulum is required. Yet, the transport mechanism for plastid fatty acids still remains enigmatic. We isolated FAX1 (fatty acid export 1), a novel protein, which inserts into the chloroplast inner envelope by α-helical membrane-spanning domains. Detailed phenotypic and ultrastructural analyses of FAX1 mutants in Arabidopsis thaliana showed that FAX1 function is crucial for biomass production, male fertility and synthesis of fatty acid-derived compounds such as lipids, ketone waxes, or pollen cell wall material. Determination of lipid, fatty acid, and wax contents by mass spectrometry revealed that endoplasmatic reticulum (ER)-derived lipids decreased when FAX1 was missing, but levels of several plastid-produced species increased. FAX1 over-expressing lines showed the opposite behavior, including a pronounced increase of triacyglycerol oils in flowers and leaves. Furthermore, the cuticular layer of stems from fax1 knockout lines was specifically reduced in C29 ketone wax compounds. Differential gene expression in FAX1 mutants as determined by DNA microarray analysis confirmed phenotypes and metabolic imbalances. Since in yeast FAX1 could complement for fatty acid transport, we concluded that FAX1 mediates fatty acid export from plastids. In vertebrates, FAX1 relatives are structurally related, mitochondrial membrane proteins of so-far unknown function. Therefore, this protein family might represent a powerful tool not only to increase lipid/biofuel production in plants but also to explore novel transport systems involved in vertebrate fatty acid and lipid metabolism. PMID:25646734

The brown adipocyte protein CIDEA promotes lipid droplet fusion via a phosphatidic acid-binding amphipathic helix

PubMed Central

Barneda, David; Planas-Iglesias, Joan; Gaspar, Maria L; Mohammadyani, Dariush; Prasannan, Sunil; Dormann, Dirk; Han, Gil-Soo; Jesch, Stephen A; Carman, George M; Kagan, Valerian; Parker, Malcolm G; Ktistakis, Nicholas T; Klein-Seetharaman, Judith; Dixon, Ann M; Henry, Susan A; Christian, Mark

2015-01-01

Maintenance of energy homeostasis depends on the highly regulated storage and release of triacylglycerol primarily in adipose tissue, and excessive storage is a feature of common metabolic disorders. CIDEA is a lipid droplet (LD)-protein enriched in brown adipocytes promoting the enlargement of LDs, which are dynamic, ubiquitous organelles specialized for storing neutral lipids. We demonstrate an essential role in this process for an amphipathic helix in CIDEA, which facilitates embedding in the LD phospholipid monolayer and binds phosphatidic acid (PA). LD pairs are docked by CIDEA trans-complexes through contributions of the N-terminal domain and a C-terminal dimerization region. These complexes, enriched at the LD–LD contact site, interact with the cone-shaped phospholipid PA and likely increase phospholipid barrier permeability, promoting LD fusion by transference of lipids. This physiological process is essential in adipocyte differentiation as well as serving to facilitate the tight coupling of lipolysis and lipogenesis in activated brown fat. DOI: http://dx.doi.org/10.7554/eLife.07485.001 PMID:26609809

TGD4 involved in endoplasmic reticulum-to-chloroplast lipid trafficking is a phosphatidic acid binding protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Z.; Xu C.; Benning, C.

The synthesis of galactoglycerolipids, which are prevalent in photosynthetic membranes, involves enzymes at the endoplasmic reticulum (ER) and the chloroplast envelope membranes. Genetic analysis of trigalactosyldiacylglycerol (TGD) proteins in Arabidopsis has demonstrated their role in polar lipid transfer from the ER to the chloroplast. The TGD1, 2, and 3 proteins resemble components of a bacterial-type ATP-binding cassette (ABC) transporter, with TGD1 representing the permease, TGD2 the substrate binding protein, and TGD3 the ATPase. However, the function of the TGD4 protein in this process is less clear and its location in plant cells remains to be firmly determined. The predicted C-terminalmore » {beta}-barrel structure of TGD4 is weakly similar to proteins of the outer cell membrane of Gram-negative bacteria. Here, we show that, like TGD2, the TGD4 protein when fused to DsRED specifically binds phosphatidic acid (PtdOH). As previously shown for tgd1 mutants, tgd4 mutants have elevated PtdOH content, probably in extraplastidic membranes. Using highly purified and specific antibodies to probe different cell fractions, we demonstrated that the TGD4 protein was present in the outer envelope membrane of chloroplasts, where it appeared to be deeply buried within the membrane except for the N-terminus, which was found to be exposed to the cytosol. It is proposed that TGD4 is either directly involved in the transfer of polar lipids, possibly PtdOH, from the ER to the outer chloroplast envelope membrane or in the transfer of PtdOH through the outer envelope membrane.« less

Effect of Selenium on Lipid and Amino Acid Metabolism in Yeast Cells.

PubMed

Kieliszek, Marek; Błażejak, Stanisław; Bzducha-Wróbel, Anna; Kot, Anna M

2018-04-19

This article discusses the effect of selenium in aqueous solutions on aspects of lipid and amino acid metabolism in the cell biomass of Saccharomyces cerevisiae MYA-2200 and Candida utilis ATCC 9950 yeasts. The yeast biomass was obtained by using waste products (potato wastewater and glycerol). Selenium, at a dose of 20 mg/L of aqueous solution, affected the differentiation of cellular morphology. Yeast enriched with selenium was characterized by a large functional diversity in terms of protein and amino acid content. The protein content in the biomass of S. cerevisiae enriched with selenium (42.6%) decreased slightly as compared to that in the control sample without additional selenium supplementation (48.4%). Moreover, yeasts of both strains enriched with selenium contained a large amount of glutamic acid, aspartic acid, lysine, and leucine. Analysis of fatty acid profiles in S. cerevisiae yeast supplemented with selenium showed an increase in the unsaturated fatty acid content (e.g., C18:1). The presence of margaric acid (C17:0) and hexadecanoic acid (C17:1) was found in the C. utilis biomass enriched with selenium, in contrast to that of S. cerevisiae. These results indicate that selenium may induce lipid peroxidation, which consequently affects the loss of integrity of the cytoplasmic membrane. Yeast enriched with selenium with optimal amino acid and lipid composition can be used to prepare a novel formula of dietary supplements, which can be applied directly to various diets for both humans and animals.

The incorporation of hydrophobic protein receptors and artificial lipid membranes.

PubMed

Reader, T A; Fiszer de Plazas, S; Salas, P J; de Robertis, E

1976-01-01

The mechanism of chemical synaptic transmission implies: 1) the existence of a specific protein receptor at the postsynaptic membrane, and 2) the interaction between the transmitter released and the receptor, thus producing a change in ionic permeability. Previous studies from our laboratory have shown that special hydrophobic proteins extracted from postsynpatic membranes of different tissues showed a high affinity binding for the different pharmacological agents. The present paper describes experiments in which different hydrophobic protein binding acetylcholine, noradrenaline, gamma-aminobutyric acid, and glutamate were incorporated into artificial lipid membranes, similar to those first described by Mueller et al. (19). The effect of the different pharmacological agents was tested under experimental conditions of voltage clamp and the d.c. current changes measured. The results were then compared for the different lipid-protein membranes employed during the steady state and during transient conductance changes. The specificity of the responses indicate that artificial lipid membranes containing these hydrophobic proteins from electroplax, myocardium, spleen capsule and shrimp muscle can be used as a model to study pharmacologic receptors.

Membrane Binding of HIV-1 Matrix Protein: Dependence on Bilayer Composition and Protein Lipidation

PubMed Central

Barros, Marilia; Nanda, Hirsh

2016-01-01

ABSTRACT By assembling in a protein lattice on the host's plasma membrane, the retroviral Gag polyprotein triggers formation of the viral protein/membrane shell. The MA domain of Gag employs multiple signals—electrostatic, hydrophobic, and lipid-specific—to bring the protein to the plasma membrane, thereby complementing protein-protein interactions, located in full-length Gag, in lattice formation. We report the interaction of myristoylated and unmyristoylated HIV-1 Gag MA domains with bilayers composed of purified lipid components to dissect these complex membrane signals and quantify their contributions to the overall interaction. Surface plasmon resonance on well-defined planar membrane models is used to quantify binding affinities and amounts of protein and yields free binding energy contributions, ΔG, of the various signals. Charge-charge interactions in the absence of the phosphatidylinositide PI(4,5)P2 attract the protein to acidic membrane surfaces, and myristoylation increases the affinity by a factor of 10; thus, our data do not provide evidence for a PI(4,5)P2 trigger of myristate exposure. Lipid-specific interactions with PI(4,5)P2, the major signal lipid in the inner plasma membrane, increase membrane attraction at a level similar to that of protein lipidation. While cholesterol does not directly engage in interactions, it augments protein affinity strongly by facilitating efficient myristate insertion and PI(4,5)P2 binding. We thus observe that the isolated MA protein, in the absence of protein-protein interaction conferred by the full-length Gag, binds the membrane with submicromolar affinities. IMPORTANCE Like other retroviral species, the Gag polyprotein of HIV-1 contains three major domains: the N-terminal, myristoylated MA domain that targets the protein to the plasma membrane of the host; a central capsid-forming domain; and the C-terminal, genome-binding nucleocapsid domain. These domains act in concert to condense Gag into a membrane

Fatty acid transport protein-2 inhibitor Grassofermata/CB5 protects cells against lipid accumulation and toxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saini, Nipun; Black, Paul N.; Montefusco, David

The inhibition of the fatty acid uptake into non-adipose tissues provides an attractive target for prevention of lipotoxicity leading to obesity-associated non-alcoholic fatty liver disease and type 2 diabetes. Fatty acid transport proteins (FATPs) are bifunctional proteins involved in the uptake and activation of fatty acids by esterification with coenzyme A. Here we characterize Grassofermata/CB5, previously identified as a fatty acid uptake inhibitor directed against HsFATP2. The compound was effective in inhibiting the uptake of fatty acids in the low micro-molar range (IC{sub 50} 8–11 μM) and prevented palmitate-mediated lipid accumulation and cell death in cell lines that are models formore » intestines, liver, muscle and pancreas. In adipocytes, uptake inhibition was less effective (IC{sub 50} 58 μM). Inhibition was specific for long chain fatty acids and was ineffective toward medium chain fatty acids, which are transported by diffusion. Kinetic analysis of Grassofermata-dependent FA transport inhibition verified a non-competitive mechanism. By comparison with Grassofermata, several atypical antipsychotic drugs previously implicated as inhibitors of FA uptake were ineffectual. In mice Grassofermata decreased absorption of {sup 13}C-oleate demonstrating its potential as a therapeutic agent. - Highlights: • Grassofermata is a small compound inhibitor of FATP2. • Uptake inhibition is specific for long chain fatty acids. • Uptake kinetics shows low specificity for adipocytes compared to other cell types. • Inhibition is by a non-competitive mechanism. • Atypical antipsychotics do not inhibit FA uptake by comparison with Grassofermata.« less

Urinary Loss of Tricarboxylic Acid Cycle Intermediates As Revealed by Metabolomics Studies: An Underlying Mechanism to Reduce Lipid Accretion by Whey Protein Ingestion?

PubMed Central

2015-01-01

Whey protein intake is associated with the modulation of energy metabolism and altered body composition both in human subjects and in animals, but the underlying mechanisms are not yet elucidated. We fed obesity-prone C57BL/6J mice high-fat diets with either casein (HF casein) or whey (HF whey) for 6 weeks. At equal energy intake and apparent fat and nitrogen digestibility, mice fed HF whey stored less energy as lipids, evident both as lower white adipose tissue mass and as reduced liver lipids, compared with HF-casein-fed mice. Explorative analyses of 48 h urine, both by 1H NMR and LC–MS metabolomic platforms, demonstrated higher urinary excretion of tricarboxylic acid (TCA) cycle intermediates citric acid and succinic acid (identified by both platforms), and cis-aconitic acid and isocitric acid (identified by LC–MS platform) in the HF whey, relative to in the HF-casein-fed mice. Targeted LC–MS analyses revealed higher citric acid and cis-aconitic acid concentrations in fed state plasma, but not in liver of HF-whey-fed mice. We propose that enhanced urinary loss of TCA cycle metabolites drain available substrates for anabolic processes, such as lipogenesis, thereby leading to reduced lipid accretion in HF-whey-fed compared to HF-casein-fed mice. PMID:24702026

Lens lipids.

PubMed

Zelenka, P S

1984-11-01

Lens cells can synthesize, degrade, and remodel lipids. Endogenous lipid synthesis, in conjunction with uptake of exogenous cholesterol and certain fatty acids, leads to the formation of a plasma membrane that is especially rich in sphingomyelin, cholesterol, and long-chain saturated fatty acids. As a result of this unusual lipid composition, lens membranes have very low fluidity, which is restricted even further by lipid-protein interactions. The composition and metabolism of membrane lipids may affect the formation of various types of cataracts. Diets rich in vegetable oils offer some protection against the formation of osmotic cataracts and the hereditary cataract of the RCS rat, although the mechanism of this effect is not clear. Vitamin E also protects against the formation of several types of cataract in vivo and in vitro, suggesting that lipid peroxidation may play a role in cataractogenesis. Certain drugs which inhibit lipid synthesis or degradation are cataractogenic, and a deficiency in cataractogenic, and a deficiency in phosphatidylserine is associated with a loss of Na+/K+ ATPase activity in several types of cataract. Human senile cataracts show a marked loss of protein-lipid interactions, although the overall lipid composition is normal. This loss of protein-lipid interactions may be related to oxidative damage to membrane-associated proteins. Interestingly, the decrease in the fluidity of lens membranes with age would counteract the formation of aqueous pores in the membrane, which can result from the oxidative cross-linking of membrane-associated proteins. Certain pathways of lipid metabolism seem to have regulatory functions. Among these are phosphatidylinositol turnover, phosphatidylethanolamine methylation, and arachidonic acid metabolism. All of these pathways function in the lens. Phosphatidylinositol turnover is correlated with the rate of lens epithelial cell division, while phosphatidylethanolamine methylation seems to be related to the

CALCIUM-INDUCED LIPID PEROXIDATION IS MEDIATED BY RHODNIUS HEME-BINDING PROTEIN (RHBP) AND PREVENTED BY VITELLIN.

PubMed

Paes, Marcia C; Silveira, Alan B; Ventura-Martins, Guilherme; Luciano, Monalisa; Coelho, Marsen G P; Todeschini, Adriane R; Bianconi, M Lucia; Atella, Georgia C; Silva-Neto, Mário A C

2015-10-01

Lipid peroxidation is promoted by the quasi-lipoxygenase (QL) activity of heme proteins and enhanced by the presence of free calcium. Unlike mammalian plasma, the hemolymph of Rhodnius prolixus, a vector of Chagas disease, contains both a free heme-binding protein (RHBP) and circulating lipoproteins. RHBP binds and prevents the heme groups of the proteins from participating in lipid peroxidation reactions. Herein, we show that despite being bound to RHBP, heme groups promote lipid peroxidation through a calcium-dependent QL reaction. This reaction is readily inhibited by the presence of ethylene glycol tetraacetic acid (EGTA), the antioxidant butylated hydroxytoluene or micromolar levels of the main yolk phosphoprotein vitellin (Vt). The inhibition of lipid peroxidation is eliminated by the in vitro dephosphorylation of Vt, indicating that this reaction depends on the interaction of free calcium ions with negatively charged phosphoamino acids. Our results demonstrate that calcium chelation mediated by phosphoproteins occurs via an antioxidant mechanism that protects living organisms from lipid peroxidation. © 2015 Wiley Periodicals, Inc.

Liver X Receptors Balance Lipid Stores in Hepatic Stellate Cells via Rab18, a Retinoid Responsive Lipid Droplet Protein

PubMed Central

O’Mahony, Fiona; Wroblewski, Kevin; O’Byrne, Sheila M.; Jiang, Hongfeng; Clerkin, Kara; Benhammou, Jihane; Blaner, William S.; Beaven, Simon W.

2014-01-01

Liver X receptors (LXRs) are determinants of hepatic stellate cell (HSC) activation and liver fibrosis. Freshly isolated HSCs from Lxrαβ−/− mice have increased lipid droplet (LD) size but the functional consequences of this are unknown. Our aim was to determine whether LXRs link cholesterol to retinoid storage in HSCs and how this impacts activation. Primary HSCs from Lxrαβ−/− and wild-type (WT) mice were profiled by gene array during in vitro activation. Lipid content was quantified by HPLC and mass spectroscopy. Primary HSCs were treated with nuclear receptor ligands, transfected with siRNA and plasmid constructs, and analyzed by immunocytochemistry. Lxrαβ−/− HSCs have increased cholesterol and retinyl esters (CEs & REs). The retinoid increase drives intrinsic retinoic acid receptor (RAR) signaling and activation occurs more rapidly in Lxrαβ−/− HSCs. We identify Rab18 as a novel retinoic acid responsive, lipid droplet associated protein that helps mediate stellate cell activation. Rab18 mRNA, protein, and membrane insertion increase during activation. Both Rab18 GTPase activity and isoprenylation are required for stellate cell lipid droplet loss and induction of activation markers. These phenomena are accelerated in the Lxrαβ−/− HSCs, where there is greater retinoic acid flux. Conversely, Rab18 knockdown retards lipid droplet loss in culture and blocks activation, just like the functional mutants. Rab18 is also induced with acute liver injury in vivo. Conclusion Retinoid and cholesterol metabolism are linked in stellate cells by the LD associated protein, Rab18. Retinoid overload helps explain the pro-fibrotic phenotype of Lxrαβ−/− mice and we establish a pivotal role for Rab18 GTPase activity and membrane insertion in wild-type stellate cell activation. Interference with Rab18 may have significant therapeutic benefit in ameliorating liver fibrosis. PMID:25482505

Guidelines for the Use of Protein Domains in Acidic Phospholipid Imaging.

PubMed

Platre, Matthieu Pierre; Jaillais, Yvon

2016-01-01

Acidic phospholipids are minor membrane lipids but critically important for signaling events. The main acidic phospholipids are phosphatidylinositol phosphates (PIPs also known as phosphoinositides), phosphatidylserine (PS), and phosphatidic acid (PA). Acidic phospholipids are precursors of second messengers of key signaling cascades or are second messengers themselves. They regulate the localization and activation of many proteins, and are involved in virtually all membrane trafficking events. As such, it is crucial to understand the subcellular localization and dynamics of each of these lipids within the cell. Over the years, several techniques have emerged in either fixed or live cells to analyze the subcellular localization and dynamics of acidic phospholipids. In this chapter, we review one of them: the use of genetically encoded biosensors that are based on the expression of specific lipid binding domains (LBDs) fused to fluorescent proteins. We discuss how to design such sensors, including the criteria for selecting the lipid binding domains of interest and to validate them. We also emphasize the care that must be taken during data analysis as well as the main limitations and advantages of this approach.

Studying lipid-protein interactions with electron paramagnetic resonance spectroscopy of spin-labeled lipids.

PubMed

Páli, Tibor; Kóta, Zoltán

2013-01-01

Spin label electron paramagnetic resonance (EPR) of lipid-protein interactions reveals crucial features of the structure and assembly of integral membrane proteins. Spin label EPR spectroscopy is the technique of choice to characterize the protein-solvating lipid shell in its highly dynamic nature, because the EPR spectra of lipids that are spin labeled close to the terminal methyl end of their acyl chains display two spectral components, those corresponding to lipids directly contacting the protein and those corresponding to lipids in the bulk fluid bilayer regions of the membrane. In this chapter, typical spin label EPR procedures are presented that allow determination of the stoichiometry of interaction of spin-labeled lipids with the intra-membranous region of membrane proteins or polypeptides, as well as the association constant of the spin-labeled lipid with respect to the host lipid. The lipids giving rise to the so-called immobile spectral component in the EPR spectrum of such samples are identified as the motionally restricted first-shell lipids solvating membrane proteins in biomembranes. Stoichiometry and selectivity are directly related to the structure of the intra-membranous sections of membrane-associated proteins or polypeptides and can be used to study the state of assembly of such proteins in the membrane. Since these characteristics of lipid-protein interactions are discussed in detail in the literature [see Marsh (Eur Biophys J 39:513-525, 2010) for a most recent review], here we focus more on how to spin label model and biomembranes and how to measure and analyze the two-component EPR spectra of spin-labeled lipids in phospholipid bilayers that contain proteins or polypeptides. After a description of how to prepare spin-labeled model and native biological membranes, we present the reader with computational procedures for determining the molar fraction of motionally restricted lipids when both, one, or none of the pure isolated-mobile or

A method for detergent-free isolation of membrane proteins in their local lipid environment.

PubMed

Lee, Sarah C; Knowles, Tim J; Postis, Vincent L G; Jamshad, Mohammed; Parslow, Rosemary A; Lin, Yu-Pin; Goldman, Adrian; Sridhar, Pooja; Overduin, Michael; Muench, Stephen P; Dafforn, Timothy R

2016-07-01

Despite the great importance of membrane proteins, structural and functional studies of these proteins present major challenges. A significant hurdle is the extraction of the functional protein from its natural lipid membrane. Traditionally achieved with detergents, purification procedures can be costly and time consuming. A critical flaw with detergent approaches is the removal of the protein from the native lipid environment required to maintain functionally stable protein. This protocol describes the preparation of styrene maleic acid (SMA) co-polymer to extract membrane proteins from prokaryotic and eukaryotic expression systems. Successful isolation of membrane proteins into SMA lipid particles (SMALPs) allows the proteins to remain with native lipid, surrounded by SMA. We detail procedures for obtaining 25 g of SMA (4 d); explain the preparation of protein-containing SMALPs using membranes isolated from Escherichia coli (2 d) and control protein-free SMALPS using E. coli polar lipid extract (1-2 h); investigate SMALP protein purity by SDS-PAGE analysis and estimate protein concentration (4 h); and detail biophysical methods such as circular dichroism (CD) spectroscopy and sedimentation velocity analytical ultracentrifugation (svAUC) to undertake initial structural studies to characterize SMALPs (∼2 d). Together, these methods provide a practical tool kit for those wanting to use SMALPs to study membrane proteins.

Effects of the lipid environment, cholesterol and bile acids on the function of the purified and reconstituted human ABCG2 protein.

PubMed

Telbisz, Ágnes; Özvegy-Laczka, Csilla; Hegedűs, Tamás; Váradi, András; Sarkadi, Balázs

2013-03-01

The human ABCG2 multidrug transporter actively extrudes a wide range of hydrophobic drugs and xenobiotics recognized by the transporter in the membrane phase. In order to examine the molecular nature of the transporter and its effects on the lipid environment, we have established an efficient protocol for the purification and reconstitution of the functional protein. We found that the drug-stimulated ATPase and the transport activity of ABCG2 are fully preserved by applying excess lipids and mild detergents during solubilization, whereas a detergent-induced dissociation of the ABCG2 dimer causes an irreversible inactivation. By using the purified and reconstituted protein we demonstrate that cholesterol is an essential activator, whereas bile acids are important modulators of ABCG2 activity. Both wild-type ABCG2 and its R482G mutant variant require cholesterol for full activity, although they exhibit different cholesterol sensitivities. Bile acids strongly decrease the basal ABCG2-ATPase activity both in the wild-type ABCG2 and in the mutant variant. These data reinforce the results for the modulatory effects of cholesterol and bile acids of ABCG2 investigated in a complex cell membrane environment. Moreover, these experiments open the possibility to perform functional and structural studies with a purified, reconstituted and highly active ABCG2 multidrug transporter.

Characterization of Thylakoid-Derived Lipid-Protein Particles Bearing the Large Subunit of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase.

PubMed Central

Smith, M. D.; Ghosh, S.; Dumbroff, E. B.; Thompson, J. E.

1997-01-01

Lipid-protein particles bearing the 55-kD ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) (EC 4.1.1.39) large subunit (RLSU) and no detectable corresponding Rubisco small subunit (RSSU) were isolated from the stroma of intact chloroplasts by flotation centrifugation. Stromal RLSU-bearing particles appear to originate from thylakoids because they can also be generated in vitro by illumination of isolated thylakoids. Their formation in vitro is largely heat denaturable and is facilitated by light or ATP. RLSU-containing lipid-protein particles range from 0.05 to 0.10 [mu]m in radius, contain the same fatty acids as thylakoids, but have a 10- to 15-fold higher free-to-esterified fatty acid ratio than thylakoids. RLSU-bearing lipid-protein particles with no detectable RSSU were also immunopurified from the populations of both stromal lipid-protein particles and those generated in vitro from illuminated thylakoids. Protease shaving indicated that the RLSU is embedded in the lipid-protein particles and that there is also a protease-protected RLSU in thylakoids. These observations collectively indicate that the RLSU associated with thylakoids is released into the stroma by light-facilitated blebbing of lipid-protein particles. The release of RLSU-containing particles may in turn be coordinated with the assembly of Rubisco holoenzyme because chaperonin 60 is also associated with lipid-protein particles isolated from stroma. PMID:12223858

Role of Transbilayer Distribution of Lipid Molecules on the Structure and Protein-Lipid Interaction of an Amyloidogenic Protein on the Membrane Surface

NASA Astrophysics Data System (ADS)

Cheng, Kwan; Cheng, Sara

We used molecular dynamics simulations to examine the effects of transbilayer distribution of lipid molecules, particularly anionic lipids with negatively charged headgroups, on the structure and binding kinetics of an amyloidogenic protein on the membrane surface and subsequent protein-induced structural disruption of the membrane. Our systems consisted of a model beta-sheet rich dimeric protein absorbed on asymmetric bilayers with neutral and anionic lipids and symmetric bilayers with neutral lipids. We observed larger folding, domain aggregation, and tilt angle of the absorbed protein on the asymmetric bilayer surfaces. We also detected more focused bilayer thinning in the asymmetric bilayer due to weak lipid-protein interactions. Our results support the mechanism that the higher lipid packing in the protein-contacting lipid leaflet promotes stronger protein-protein but weaker protein-lipid interactions of an amyloidogenic protein on the membrane surface. We speculate that the observed surface-induced structural and protein-lipid interaction of our model amyloidogenic protein may play a role in the early membrane-associated amyloid cascade pathway that leads to membrane structural damage of neurons in Alzheimer's disease. NSF ACI-1531594.

Functional and in vitro gastric digestibility of the whey protein hydrogel loaded with nanostructured lipid carriers and gelled via citric acid-mediated crosslinking.

PubMed

Hashemi, Behnaz; Madadlou, Ashkan; Salami, Maryam

2017-12-15

Nanostructured lipid carriers (NLCs) with mean size of 347nm were fabricated and added into a heat-denatured whey protein solution. The subsequent crosslinking of proteins by citric acid or CaCl 2 resulted in the formation of cold-set hydrogels. Fourier transform infrared spectroscopy (FTIR) proposed formation of more hydrogen bonds in gel due to NLC loading or citric acid-mediated gelation. It was also found based on FITR spectroscopy that citric acid crosslinking disordered whey proteins. Scanning electron microscopy (SEM) imaging showed a non-porous and finely meshed microstructure for the crosslinked gels compared to non-crosslinked counterparts. Crosslinking also increased the firmness and water-holding capacity of gels. In pepsin-free fluid, a strong correlation existed between reduction in gel swellability and digestibility over periods up to 60min due to NLC loading and citric acid gelation. However, in peptic fluid, NLC loading and citric acid crosslinking brought about much higher decrease in digestibility than swellability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecular simulation of the effect of cholesterol on lipid-mediated protein-protein interactions.

PubMed

de Meyer, Frédérick J-M; Rodgers, Jocelyn M; Willems, Thomas F; Smit, Berend

2010-12-01

Experiments and molecular simulations have shown that the hydrophobic mismatch between proteins and membranes contributes significantly to lipid-mediated protein-protein interactions. In this article, we discuss the effect of cholesterol on lipid-mediated protein-protein interactions as function of hydrophobic mismatch, protein diameter and protein cluster size, lipid tail length, and temperature. To do so, we study a mesoscopic model of a hydrated bilayer containing lipids and cholesterol in which proteins are embedded, with a hybrid dissipative particle dynamics-Monte Carlo method. We propose a mechanism by which cholesterol affects protein interactions: protein-induced, cholesterol-enriched, or cholesterol-depleted lipid shells surrounding the proteins affect the lipid-mediated protein-protein interactions. Our calculations of the potential of mean force between proteins and protein clusters show that the addition of cholesterol dramatically reduces repulsive lipid-mediated interactions between proteins (protein clusters) with positive mismatch, but does not affect attractive interactions between proteins with negative mismatch. Cholesterol has only a modest effect on the repulsive interactions between proteins with different mismatch. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Low-ω3 Fatty Acid and Soy Protein Attenuate Alcohol-Induced Fatty Liver and Injury by Regulating the Opposing Lipid Oxidation and Lipogenic Signaling Pathways

PubMed Central

Reyes-Gordillo, Karina; Shah, Ruchi; Varatharajalu, Ravi; Garige, Mamatha; Leckey, Leslie C.

2016-01-01

Chronic ethanol-induced downregulation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) and upregulation of peroxisome proliferator-activated receptor gamma coactivator 1-beta (PGC1β) affect hepatic lipid oxidation and lipogenesis, respectively, leading to fatty liver injury. Low-ω3 fatty acid (Low-ω3FA) that primarily regulates PGC1α and soy protein (SP) that seems to have its major regulatory effect on PGC1β were evaluated for their protective effects against ethanol-induced hepatosteatosis in rats fed with Lieber-deCarli control or ethanol liquid diets with high or low ω3FA fish oil and soy protein. Low-ω3FA and SP opposed the actions of chronic ethanol by reducing serum and liver lipids with concomitant decreased fatty liver. They also prevented the downregulation of hepatic Sirtuin 1 (SIRT1) and PGC1α and their target fatty acid oxidation pathway genes and attenuated the upregulation of hepatic PGC1β and sterol regulatory element-binding protein 1c (SREBP1c) and their target lipogenic pathway genes via the phosphorylation of 5′ adenosine monophosphate-activated protein kinase (AMPK). Thus, these two novel modulators attenuate ethanol-induced hepatosteatosis and consequent liver injury potentially by regulating the two opposing lipid oxidation and lipogenic pathways. PMID:28074114

A novel lipid transfer protein from the pea Pisum sativum: isolation, recombinant expression, solution structure, antifungal activity, lipid binding, and allergenic properties.

PubMed

Bogdanov, Ivan V; Shenkarev, Zakhar O; Finkina, Ekaterina I; Melnikova, Daria N; Rumynskiy, Eugene I; Arseniev, Alexander S; Ovchinnikova, Tatiana V

2016-04-30

Plant lipid transfer proteins (LTPs) assemble a family of small (7-9 kDa) ubiquitous cationic proteins with an ability to bind and transport lipids as well as participate in various physiological processes including defense against phytopathogens. They also form one of the most clinically relevant classes of plant allergens. Nothing is known to date about correlation between lipid-binding and IgE-binding properties of LTPs. The garden pea Pisum sativum is widely consumed crop and important allergenic specie of the legume family. This work is aimed at isolation of a novel LTP from pea seeds and characterization of its structural, functional, and allergenic properties. Three novel lipid transfer proteins, designated as Ps-LTP1-3, were found in the garden pea Pisum sativum, their cDNA sequences were determined, and mRNA expression levels of all the three proteins were measured at different pea organs. Ps-LTP1 was isolated for the first time from the pea seeds, and its complete amino acid sequence was determined. The protein exhibits antifungal activity and is a membrane-active compound that causes a leakage from artificial liposomes. The protein binds various lipids including bioactive jasmonic acid. Spatial structure of the recombinant uniformly (13)C,(15)N-labelled Ps-LTP1 was solved by heteronuclear NMR spectroscopy. In solution the unliganded protein represents the mixture of two conformers (relative populations ~ 85:15) which are interconnected by exchange process with characteristic time ~ 100 ms. Hydrophobic residues of major conformer form a relatively large internal tunnel-like lipid-binding cavity (van der Waals volume comes up to ~1000 Å(3)). The minor conformer probably corresponds to the protein with the partially collapsed internal cavity. For the first time conformational heterogeneity in solution was shown for an unliganded plant lipid transfer protein. Heat denaturation profile and simulated gastrointestinal digestion assay showed that Ps

Smart polymer brush nanostructures guide the self-assembly of pore-spanning lipid bilayers with integrated membrane proteins

NASA Astrophysics Data System (ADS)

Wilhelmina de Groot, G.; Demarche, Sophie; Santonicola, M. Gabriella; Tiefenauer, Louis; Vancso, G. Julius

2014-01-01

Nanopores in arrays on silicon chips are functionalized with pH-responsive poly(methacrylic acid) (PMAA) brushes and used as supports for pore-spanning lipid bilayers with integrated membrane proteins. Robust platforms are created by the covalent grafting of polymer brushes using surface-initiated atom transfer radical polymerization (ATRP), resulting in sensor chips that can be successfully reused over several assays. His-tagged proteins are selectively and reversibly bound to the nitrilotriacetic acid (NTA) functionalization of the PMAA brush, and consequently lipid bilayer membranes are formed. The enhanced membrane resistance as determined by electrochemical impedance spectroscopy and free diffusion of dyed lipids observed as fluorescence recovery after photobleaching confirmed the presence of lipid bilayers. Immobilization of the His-tagged membrane proteins on the NTA-modified PMAA brush near the pore edges is characterized by fluorescence microscopy. This system allows us to adjust the protein density in free-standing bilayers, which are stabilized by the polymer brush underneath. The potential application of the integrated platform for ion channel protein assays is demonstrated.

Occurrence of fatty acid chlorohydrins in jellyfish lipids.

PubMed

White, R H; Hager, L P

1977-11-01

Fatty acid chlorohydrins are characterized as lipid components of an edible jellyfish. The four isomers 9-chloro-10-hydroxypalmitic acid, 10-chloro-9-hydroxypalmitic acid, 9-chloro-10-hydroxystearic acid, and 10-chloro-9-hydroxystearic acid were identified by gas chromatography-mass spectrometry comparison of the methyl esters and their trimethylsilyl derivatives with known synthetic samples. Two additional isomers, 11-chloro-12-hydroxystearic acid and 12-chloro-11-hydroxystearic acid, were also found in the lipid by the identification of the expected mass spectral fragments of the trimethylsilyl (Me3Si) derivative of their methyl esters. These six isomeric compounds represented approximately 1.4% of the total extractable jellyfish lipid and were released from the lipid as methyl esters by boron trifluoride-methanol treatment. These isomers account for only about 30% of the organic chlorine in the lipid. Evidence is given that the remaining organic chlorine is also present as fatty acid chlorohydrins containing more than one hydroxyl group.

Impact of Lipid and Protein Co-oxidation on Digestibility of Dairy Proteins in Oil-in-Water (O/W) Emulsions.

PubMed

Obando, Mónica; Papastergiadis, Antonios; Li, Shanshan; De Meulenaer, Bruno

2015-11-11

Enrichment of polyunsaturated fatty acids (PUFAs) is a growing trend in the food industry. However, PUFAs are known to be susceptible to lipid oxidation. It has been shown that oxidizing lipids react with proteins present in the food and that as a result polymeric protein complexes are produced. Therefore, the aim of this work was to investigate the impact of lipid and protein co-oxidation on protein digestibility. Casein and whey protein (6 mg/mL) based emulsions with 1% oil with different levels of PUFAs were subjected to respectively autoxidation and photo-oxidation. Upon autoxidation at 70 °C, protein digestibility of whey protein based emulsions containing fish oil decreased to 47.7 ± 0.8% after 48 h, whereas in the controls without oil 67.8 ± 0.7% was observed. Upon photo-oxidation at 4 °C during 30 days, mainly casein-based emulsions containing fish oil were affected: the digestibility amounted to 43.9 ± 1.2%, whereas in the control casein solutions without oil, 72.6 ± 0.2% of the proteins were digestible. Emulsions containing oils with high PUFA levels were more prone to lipid oxidation and thus upon progressive oxidation showed a higher impact on protein digestibility.

Parsing the life-shortening effects of dietary protein: effects of individual amino acids

PubMed Central

Bouchebti, Sofia; Bazazi, Sepideh; Le Hesran, Sophie; Puga, Camille; Latil, Gérard; Simpson, Stephen J.

2017-01-01

High-protein diets shorten lifespan in many organisms. Is it because protein digestion is energetically costly or because the final products (the amino acids) are harmful? To answer this question while circumventing the life-history trade-off between reproduction and longevity, we fed sterile ant workers on diets based on whole proteins or free amino acids. We found that (i) free amino acids shortened lifespan even more than proteins; (ii) the higher the amino acid-to-carbohydrate ratio, the shorter ants lived and the lower their lipid reserves; (iii) for the same amino acid-to-carbohydrate ratio, ants eating free amino acids had more lipid reserves than those eating whole proteins; and (iv) on whole protein diets, ants seem to regulate food intake by prioritizing sugar, while on free amino acid diets, they seem to prioritize amino acids. To test the effect of the amino acid profile, we tested diets containing proportions of each amino acid that matched the ant's exome; surprisingly, longevity was unaffected by this change. We further tested diets with all amino acids under-represented except one, finding that methionine, serine, threonine and phenylalanine are especially harmful. All together, our results show certain amino acids are key elements behind the high-protein diet reduction in lifespan. PMID:28053059

Parsing the life-shortening effects of dietary protein: effects of individual amino acids.

PubMed

Arganda, Sara; Bouchebti, Sofia; Bazazi, Sepideh; Le Hesran, Sophie; Puga, Camille; Latil, Gérard; Simpson, Stephen J; Dussutour, Audrey

2017-01-11

High-protein diets shorten lifespan in many organisms. Is it because protein digestion is energetically costly or because the final products (the amino acids) are harmful? To answer this question while circumventing the life-history trade-off between reproduction and longevity, we fed sterile ant workers on diets based on whole proteins or free amino acids. We found that (i) free amino acids shortened lifespan even more than proteins; (ii) the higher the amino acid-to-carbohydrate ratio, the shorter ants lived and the lower their lipid reserves; (iii) for the same amino acid-to-carbohydrate ratio, ants eating free amino acids had more lipid reserves than those eating whole proteins; and (iv) on whole protein diets, ants seem to regulate food intake by prioritizing sugar, while on free amino acid diets, they seem to prioritize amino acids. To test the effect of the amino acid profile, we tested diets containing proportions of each amino acid that matched the ant's exome; surprisingly, longevity was unaffected by this change. We further tested diets with all amino acids under-represented except one, finding that methionine, serine, threonine and phenylalanine are especially harmful. All together, our results show certain amino acids are key elements behind the high-protein diet reduction in lifespan. © 2017 The Author(s).

Mutual adaptation of a membrane protein and its lipid bilayer during conformational changes.

PubMed

Sonntag, Yonathan; Musgaard, Maria; Olesen, Claus; Schiøtt, Birgit; Møller, Jesper Vuust; Nissen, Poul; Thøgersen, Lea

2011-01-01

The structural elucidation of membrane proteins continues to gather pace, but we know little about their molecular interactions with the lipid environment or how they interact with the surrounding bilayer. Here, with the aid of low-resolution X-ray crystallography, we present direct structural information on membrane interfaces as delineated by lipid phosphate groups surrounding the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) in its phosphorylated and dephosphorylated Ca(2+)-free forms. The protein-lipid interactions are further analysed using molecular dynamics simulations. We find that SERCA adapts to membranes of different hydrophobic thicknesses by inducing local deformations in the lipid bilayers and by undergoing small rearrangements of the amino-acid side chains and helix tilts. These mutually adaptive interactions allow smooth transitions through large conformational changes associated with the transport cycle of SERCA, a strategy that may be of general nature for many membrane proteins.

Consequences of Lipid Droplet Coat Protein Downregulation in Liver Cells

PubMed Central

Bell, Ming; Wang, Hong; Chen, Hui; McLenithan, John C.; Gong, Da-Wei; Yang, Rong-Zee; Yu, Daozhan; Fried, Susan K.; Quon, Michael J.; Londos, Constantine; Sztalryd, Carole

2008-01-01

OBJECTIVE—Accumulation of intracellular lipid droplets (LDs) in non-adipose tissues is recognized as a strong prognostic factor for the development of insulin resistance in obesity. LDs are coated with perilipin, adipose differentiation–related protein, tail interacting protein of 47 kd (PAT) proteins that are thought to regulate LD turnover by modulating lipolysis. Our hypothesis is that PAT proteins modulate LD metabolism and therefore insulin resistance. RESEARCH DESIGN AND METHODS—We used a cell culture model (murine AML12 loaded with oleic acid) and small interfering RNA to directly assess the impact of PAT proteins on LD accumulation, lipid metabolism, and insulin action. PAT proteins associated with excess fat deposited in livers of diet-induced obese (DIO) mice were also measured. RESULTS—Cells lacking PAT proteins exhibited a dramatic increase in LD size and a decrease in LD number. Further, the lipolytic rate increased by ∼2- to 2.5-fold in association with increased adipose triglyceride lipase (ATGL) at the LD surface. Downregulation of PAT proteins also produced insulin resistance, as indicated by decreased insulin stimulation of Akt phosphorylation (P < 0.001). Phosphoinositide-dependent kinase-1 and phosphoinositide 3-kinase decreased, and insulin receptor substrate-1 307 phosphorylation increased. Increased lipids in DIO mice livers were accompanied by changes in PAT composition but also increased ATGL, suggesting a relative PAT deficiency. CONCLUSIONS—These data establish an important role for PAT proteins as surfactant at the LD surface, packaging lipids in smaller units and restricting access of lipases and thus preventing insulin resistance. We suggest that a deficiency of PAT proteins relative to the quantity of ectopic fat could contribute to cellular dysfunction in obesity and type 2 diabetes. PMID:18487449

Lipid-protein nanodiscs promote in vitro folding of transmembrane domains of multi-helical and multimeric membrane proteins.

PubMed

Shenkarev, Zakhar O; Lyukmanova, Ekaterina N; Butenko, Ivan O; Petrovskaya, Lada E; Paramonov, Alexander S; Shulepko, Mikhail A; Nekrasova, Oksana V; Kirpichnikov, Mikhail P; Arseniev, Alexander S

2013-02-01

Production of helical integral membrane proteins (IMPs) in a folded state is a necessary prerequisite for their functional and structural studies. In many cases large-scale expression of IMPs in cell-based and cell-free systems results in misfolded proteins, which should be refolded in vitro. Here using examples of the bacteriorhodopsin ESR from Exiguobacterium sibiricum and full-length homotetrameric K(+) channel KcsA from Streptomyces lividans we found that the efficient in vitro folding of the transmembrane domains of the polytopic and multimeric IMPs could be achieved during the protein encapsulation into the reconstructed high-density lipoprotein particles, also known as lipid-protein nanodiscs. In this case the self-assembly of the IMP/nanodisc complexes from a mixture containing apolipoprotein, lipids and the partially denatured protein solubilized in a harsh detergent induces the folding of the transmembrane domains. The obtained folding yields showed significant dependence on the properties of lipids used for nanodisc formation. The largest recovery of the spectroscopically active ESR (~60%) from the sodium dodecyl sulfate (SDS) was achieved in the nanodiscs containing anionic saturated lipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPG) and was approximately twice lower in the zwitterionic DMPC lipid. The reassembly of tetrameric KcsA from the acid-dissociated monomer solubilized in SDS was the most efficient (~80%) in the nanodiscs containing zwitterionic unsaturated lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). The charged and saturated lipids provided lower tetramer quantities, and the lowest yield (<20%) was observed in DMPC. The overall yield of the ESR and KcsA folding was mainly restricted by the efficiency of the protein encapsulation into the nanodiscs. Copyright © 2012 Elsevier B.V. All rights reserved.

Lipid monolayer structure and interactions in the presence of peptides and proteins

NASA Astrophysics Data System (ADS)

Freites, Juan Alfredo

Structural aspects of two simple model systems, protein-lipid monolayer and peptide-lipid monolayer, were studied by experimental and computer simulation techniques. In both cases, both the choice of system and the approach employed to studying it, were motivated by specific biological problems. The interaction of annexin A1 with monolayers of dipalmitoylphosphatidylcholine (DPPC) was studied by fluorescence microscopy as a function of lipid monolayer phase and pH. It was shown that the annexin A1-DPPC interaction depends strongly on both the domain structure and phase behavior of the DPPC monolayer, and only weakly on the subphase pH. Annexin A1 was found to be line-active, adsorbing preferentially at phase boundaries. Also, annexin A1 was found to form networks in the presence of a domain structure in the lipid monolayer. Molecular dynamics simulations were carried out on a model system composed of a surfactant protein B peptide, SP-B1--25, and a monolayer of hexadecanoic acid. A detailed structural characterization was performed as a function of the lipid monolayer specic area. It was found that the peptide remains inserted in the monolayer up to values of specific area corresponding to an untilted condensed phase of the pure hexadecanoic acid monolayer. The system remains stable by altering the conformational order of both the anionic lipid monolayer and the peptide secondary structure, and effectively constitutes a unique disordered lipid-peptide monolayer phase. Two elements appear to be key for the constitution of this phase: an electrostatic interaction between the cationic residues of the peptide with the anionic headgroups of the lipids, and an exclusion of the aromatic residues on the hydrophobic end of the peptide from the hydrophilic and aqueous regions of the system. A direct comparison between molecular dynamics simulations and laboratory experiments was performed for hexadecanoic acid monolayer systems. In order to simulate specific points on the

Pyrolysis characteristics and pathways of protein, lipid and carbohydrate isolated from microalgae Nannochloropsis sp.

PubMed

Wang, Xin; Sheng, Lili; Yang, Xiaoyi

2017-04-01

Microalgal components were isolated gradually to get lipid-rich, protein-rich and carbohydrate-rich components. The aim of this work was to study pyrolysis mechanism of microalgae by real isolated real algae components. Thermogrametric analysis (DTG) curve of microalgae was fitted by single pyrolysis curves of protein, lipid and carbohydrate except special zones, which likely affected by cell disruption and hydrolysis mass loss. Experimental microalgae liquefaction without water index N was 0.6776, 0.3861 and 0.2856 for isolated lipid, protein and carbohydrate. Pyrolysis pathways of lipid are decarboxylation, decarbonylation, fragmentation of glycerin moieties and steroid to form hydrocarbons, carboxylic acids and esters. Pyrolysis pathways of protein are decarboxylation, deamination, hydrocarbon residue fragmentation, dimerization and fragmentation of peptide bonds to form amide/amines/nitriles, esters, hydrocarbons and N-heterocyclic compounds, especially diketopiperazines (DKPs). Pyrolysis pathways of carbohydrate are dehydrated reactions and further fragmentation to form ketones and aldehyde, decomposition of lignin to form phenols, and fragmentation of lipopolysaccharides. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selected wheat seed defense proteins exhibit competitive binding to model microbial lipid interfaces.

PubMed

Sanders, Michael R; Clifton, Luke A; Neylon, Cameron; Frazier, Richard A; Green, Rebecca J

2013-07-17

Puroindolines (Pins) and purothionins (Pths) are basic, amphiphilic, cysteine-rich wheat proteins that play a role in plant defense against microbial pathogens. This study examined the co-adsorption and sequential addition of Pins (Pin-a, Pin-b, and a mutant form of Pin-b with Trp-44 to Arg-44 substitution) and β-purothionin (β-Pth) model anionic lipid layers using a combination of surface pressure measurements, external reflection FTIR spectroscopy, and neutron reflectometry. Results highlighted differences in the protein binding mechanisms and in the competitive binding and penetration of lipid layers between respective Pins and β-Pth. Pin-a formed a blanket-like layer of protein below the lipid surface that resulted in the reduction or inhibition of β-Pth penetration of the lipid layer. Wild-type Pin-b participated in co-operative binding with β-Pth, whereas the mutant Pin-b did not bind to the lipid layer in the presence of β-Pth. The results provide further insight into the role of hydrophobic and cationic amino acid residues in antimicrobial activity.

Protein membrane interaction: effect of myelin basic protein on the dynamics of oriented lipids

NASA Astrophysics Data System (ADS)

Natali, F.; Relini, A.; Gliozzi, A.; Rolandi, R.; Cavatorta, P.; Deriu, A.; Fasano, A.; Riccio, P.

2003-08-01

We have studied the effect of physiological amounts of myelin basic protein (MBP) on pure dimyristoyl L-α-phosphatidic acid (DMPA) oriented membranes. The investigation has been carried out using several complementary experimental methods to provide a detailed characterization of the proteo-lipid complexes. In particular, taking advantage of the power of the quasi-elastic neutron scattering (QENS) technique as optimal probe in biology, a significant effect is suggested to be induced by MBP on the anisotropy of lipid dynamics across the liquid-gel phase transition. Thus, the enhancement of the spatially restricted, vertical translation motion of DMPA is suggested to be the main responsible for the increased contribution of the out of plane lipid dynamics observed at 340 K.

Optimised purification and characterisation of lipid transfer protein 1 (LTP1) and its lipid-bound isoform LTP1b from barley malt.

PubMed

Nieuwoudt, Melanie; Lombard, Nicolaas; Rautenbach, Marina

2014-08-15

In beer brewing, brewers worldwide strive to obtain product consistency in terms of flavour, colour and foam. Important proteins contributing to beer foam are lipid transfer proteins (LTPs), in particular LTP1 and its lipid-bound isoform LTP1b, which are known to transport lipids in vivo and prevent lipids from destabilising the beer foam. LTP1 and LTP1b were successfully purified using only five purification steps with a high purified protein yield (160 mg LTP1 and LTP1b from 200 g barley). Circular dichroism of LTP1 and LTP1b confirmed that both proteins are highly tolerant to high temperatures (>90 °C) and are pH stable, particularly at a neutral to a more basic pH. Only LTP1 exhibited antiyeast and thermo-stable lytic activity, while LTP1b was inactive, indicating that the fatty acid moiety compromised the antimicrobial activity of LTP1. This lack in antiyeast activity and the positive foam properties of LTP1b would benefit beer fermentation and quality. Copyright © 2014 Elsevier Ltd. All rights reserved.

Surfactant protein B: lipid interactions of synthetic peptides representing the amino-terminal amphipathic domain.

PubMed Central

Bruni, R; Taeusch, H W; Waring, A J

1991-01-01

The mechanisms by which pulmonary surfactant protein B (SP-B) affects the surface activity of surfactant lipids are unclear. We have studied the peptide/lipid interactions of the amino-terminal amphipathic domain of SP-B by comparing the secondary conformations and surface activities of a family of synthetic peptides based on the native human SP-B sequence, modified by site-specific amino acid substitutions. Circular dichroism measurements show an alpha-helical structure correlating with the ability of the peptides to interact with lipids and with the surface activity of peptide/lipid dispersions. Amino acid substitutions altering either the charge or the hydrophobicity of the residues lowered the helical content and reduced the association of the aminoterminal segment with lipid dispersions. Surface activity of peptide/lipid mixtures was maximally altered by reversal of charge in synthetic peptides. These observations indicate that electrostatic interactions and hydrophobicity are important factors in determining optimal structure and function of surfactant peptides in lipid dispersions. Images PMID:1871144

Crystallizing Membrane Proteins Using Lipidic Mesophases

PubMed Central

Caffrey, Martin; Cherezov, Vadim

2009-01-01

A detailed protocol for crystallizing membrane proteins that makes use of lipidic mesophases is described. This has variously been referred to as the lipid cubic phase or in meso method. The method has been shown to be quite general in that it has been used to solve X-ray crystallographic structures of prokaryotic and eukaryotic proteins, proteins that are monomeric, homo- and hetero-multimeric, chromophore-containing and chromophore-free, and α-helical and β-barrel proteins. Its most recent successes are the human engineered β2-adrenergic and adenosine A2A G protein-coupled receptors. Protocols are provided for preparing and characterizing the lipidic mesophase, for reconstituting the protein into the monoolein-based mesophase, for functional assay of the protein in the mesophase, and for setting up crystallizations in manual mode. Methods for harvesting micro-crystals are also described. The time required to prepare the protein-loaded mesophase and to set up a crystallization plate manually is about one hour. PMID:19390528

Impact of Interfacial Composition on Lipid and Protein Co-Oxidation in Oil-in-Water Emulsions Containing Mixed Emulisifers.

PubMed

Zhu, Zhenbao; Zhao, Cui; Yi, Jianhua; Liu, Ning; Cao, Yuangang; Decker, Eric A; McClements, David Julian

2018-05-02

The impact of interfacial composition on lipid and protein co-oxidation in oil-in-water emulsions containing a mixture of proteins and surfactants was investigated. The emulsions consisted of 5% v/v walnut oil, 0.5% w/v whey protein isolate (WPI), and 0 to 0.4% w/v Tween 20 (pH 3 and pH 7). The protein surface load, magnitude of the ξ-potential, and mean particle diameter of the emulsions decreased as the Tween 20 concentration was increased, indicating the whey proteins were displaced by this nonionic surfactant. The whey proteins were displaced from the lipid droplet surfaces more readily at pH 3 than at pH 7, which may have been due to differences in the conformation or interactions of the proteins at the droplet surfaces at different pH values. Emulsions stabilized by whey proteins alone had relatively low lipid oxidation rates when incubated in the dark at 45 °C for up to 8 days, as determined by measuring lipid hydroperoxides and 2-thiobarbituric acid-reactive substances (TBARS). Conversely, the whey proteins themselves were rapidly oxidized, as shown by carbonyl formation, intrinsic fluorescence, sulfhydryl group loss, and electrophoresis measurements. Displacement of whey proteins from the interface by Tween 20 reduced protein oxidation but promoted lipid oxidation. These results indicated that the adsorbed proteins were more prone to oxidation than the nonadsorbed proteins, and therefore, they could act as better antioxidants. Protein oxidation was faster, while lipid oxidation was slower at pH 3 than at pH 7, which was attributed to a higher antioxidant activity of whey proteins under acidic conditions. These results highlight the importance of interfacial composition and solution pH on the oxidative stability of emulsions containing mixed emulsifiers.

Postprandial triglyceride-rich lipoproteins regulate perilipin-2 and perilipin-3 lipid-droplet-associated proteins in macrophages.

PubMed

Varela, Lourdes M; López, Sergio; Ortega-Gómez, Almudena; Bermúdez, Beatriz; Buers, Insa; Robenek, Horst; Muriana, Francisco J G; Abia, Rocío

2015-04-01

Lipid accumulation in macrophages contributes to atherosclerosis. Within macrophages, lipids are stored in lipid droplets (LDs); perilipin-2 and perilipin-3 are the main LD-associated proteins. Postprandial triglyceride (TG)-rich lipoproteins induce LD accumulation in macrophages. The role of postprandial lipoproteins in perilipin-2 and perilipin-3 regulation was studied. TG-rich lipoproteins (TRLs) induced the levels of intracellular TGs, LDs and perilipin-2 protein expression in THP-1 macrophages and in Apoe(-/-) mice bone-marrow-derived macrophages with low and high basal levels of TGs. Perilipin-3 was only synthesized in mice macrophages with low basal levels of TGs. The regulation was dependent on the fatty acid composition of the lipoproteins; monounsaturated and polyunsaturated fatty acids (PUFAs) more strongly attenuated these effects compared with saturated fatty acids. In THP-1 macrophages, immunofluorescence microscopy and freeze-fracture immunogold labeling indicated that the lipoproteins translocated perilipin-3 from the cytoplasm to the LD surface; only the lipoproteins that were rich in PUFAs suppressed this effect. Chemical inhibition showed that lipoproteins induced perilipin-2 protein expression through the peroxisome proliferator-activated nuclear receptor (PPAR) PPARα and PPARγ pathways. Overall, our data indicate that postprandial TRLs may be involved in atherosclerotic plaque formation through the regulation of perilipin-2 and perilipin-3 proteins in macrophages. Because the fatty acid composition of the lipoproteins is dependent on the type of fat consumed, the ingestion of olive oil, which is rich in monounsaturated fatty acids, and fish oil, which is rich in omega-3 fatty acids, can be considered a good nutritional strategy to reduce the risk of atherosclerosis by LD-associated proteins decrease. Copyright © 2015 Elsevier Inc. All rights reserved.

Lipid biosensor interactions with wild type and matrix deletion HIV-1 Gag proteins.

PubMed

Barklis, Eric; Staubus, August O; Mack, Andrew; Harper, Logan; Barklis, Robin Lid; Alfadhli, Ayna

2018-05-01

The matrix (MA) domain of the HIV-1 precursor Gag protein (PrGag) has been shown interact with the HIV-1 envelope (Env) protein, and to direct PrGag proteins to plasma membrane (PM) assembly sites by virtue of its affinity to phosphatidylinositol-4,5-bisphosphate (PI[4,5]P2). Unexpectedly, HIV-1 viruses with large MA deletions (ΔMA) have been shown to be conditionally infectious as long as they are matched with Env truncation mutant proteins or alternative viral glycoproteins. To characterize the interactions of wild type (WT) and ΔMA Gag proteins with PI(4,5)P2 and other acidic phospholipids, we have employed a set of lipid biosensors as probes. Our investigations showed marked differences in WT and ΔMA Gag colocalization with biosensors, effects on biosensor release, and association of biosensors with virus-like particles. These results demonstrate an alternative approach to the analysis of viral protein-lipid associations, and provide new data as to the lipid compositions of HIV-1 assembly sites. Copyright © 2018 Elsevier Inc. All rights reserved.

Electrostatic interactions during acidic phospholipid reactivation of DnaA protein, the Escherichia coli initiator of chromosomal replication.

PubMed

Kitchen, J L; Li, Z; Crooke, E

1999-05-11

The initiation of Escherichia coli chromosomal replication by DnaA protein is strongly influenced by the tight binding of the nucleotides ATP and ADP. Anionic phospholipids in a fluid bilayer promote the conversion of inactive ADP-DnaA protein to replicatively active ATP-DnaA protein in vitro, and thus likely play a key role in regulating DnaA activity. Previous studies have revealed that, during this reactivation, a specific region of DnaA protein inserts into the hydrophobic portion of the lipid bilayer in an acidic phospholipid-dependent manner. To elucidate the requirement for acidic phospholipids in the reactivation process, the contribution of electrostatic forces in the interaction of DnaA and lipid was examined. DnaA-lipid binding required anionic phospholipids, and DnaA-lipid binding as well as lipid-mediated release of DnaA-bound nucleotide were inhibited by increased ionic strength, suggesting the involvement of electrostatic interactions in these processes. As the vesicular content of acidic phospholipids was increased, both nucleotide release and DnaA-lipid binding increased in a linear, parallel manner. Given that DnaA-membrane binding, the insertion of DnaA into the membrane, and the consequent nucleotide release all require anionic phospholipids, the acidic headgroup may be necessary to recruit DnaA protein to the membrane for insertion and subsequent reactivation for replication.

Chemically Stable Lipids for Membrane Protein Crystallization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishchenko, Andrii; Peng, Lingling; Zinovev, Egor

2017-05-01

The lipidic cubic phase (LCP) has been widely recognized as a promising membrane-mimicking matrix for biophysical studies of membrane proteins and their crystallization in a lipidic environment. Application of this material to a wide variety of membrane proteins, however, is hindered due to a limited number of available host lipids, mostly monoacylglycerols (MAGs). Here, we designed, synthesized, and characterized a series of chemically stable lipids resistant to hydrolysis, with properties complementary to the widely used MAGs. In order to assess their potential to serve as host lipids for crystallization, we characterized the phase properties and lattice parameters of mesophases mademore » of two most promising lipids at a variety of different conditions by polarized light microscopy and small-angle X-ray scattering. Both lipids showed remarkable chemical stability and an extended LCP region in the phase diagram covering a wide range of temperatures down to 4 °C. One of these lipids has been used for crystallization and structure determination of a prototypical membrane protein bacteriorhodopsin at 4 and 20 °C.« less

Specific Adhesion of Lipid Membranes Can Simultaneously Produce Two Types of Lipid and Protein Heterogeneities

NASA Astrophysics Data System (ADS)

Shindell, Orrin; Micah, Natalie; Ritzer, Max; Gordon, Vernita

2015-03-01

Living cells adhere to one another and their environment. Adhesion is associated with re-organization of the lipid and protein components of the cell membrane. The resulting heterogeneities are functional structures involved in biological processes. We use artificial lipid membranes that contain a single type of binding protein. Before adhesion, the lipid, protein, and dye components in the membrane are well-mixed and constitute a single disordered-liquid phase (Ld) . After adhesion, two distinct types of heterogeneities coexist in the adhesion zone: a central domain of ordered lipid phase that excludes both binding proteins and membrane dye, and a peripheral domain of disordered lipid phase that is densely packed with adhesion proteins and enriched in membrane dye relative to the non-adhered portion of the vesicle. Thus, we show that adhesion that is mediated by only one type of protein can organize the lipid and protein components of the membranes into heterogeneities that resemble those found in biology, for example the immune synapse.

Lipid-binding proteins modulate ligand-dependent trans-activation by peroxisome proliferator-activated receptors and localize to the nucleus as well as the cytoplasm.

PubMed

Helledie, T; Antonius, M; Sorensen, R V; Hertzel, A V; Bernlohr, D A; Kølvraa, S; Kristiansen, K; Mandrup, S

2000-11-01

Peroxisome proliferator-activated receptors (PPARs) are activated by a variety of fatty acids, eicosanoids, and hypolipidemic and insulin-sensitizing drugs. Many of these compounds bind avidly to members of a family of small lipid-binding proteins, the fatty acid-binding proteins (FABPs). Fatty acids are activated to CoA esters, which bind with high affinity to the acyl-CoA-binding protein (ACBP). Thus, the availability of known and potential PPAR ligands may be regulated by lipid-binding proteins. In this report we show by transient transfection of CV-1 cells that coexpression of ACBP and adipocyte lipid-binding protein (ALBP) exerts a ligand- and PPAR subtype-specific attenuation of PPAR-mediated trans-activation, suggesting that lipid-binding proteins, when expressed at high levels, may function as negative regulators of PPAR activation by certain ligands. Expression of ACBP, ALBP, and keratinocyte lipid-binding protein (KLBP) is induced during adipocyte differentiation, a process during which PPARgamma plays a prominent role. We present evidence that endogenous ACBP, ALBP, and KLBP not only localize to the cytoplasm but also exhibit a prominent nuclear localization in 3T3-L1 adipocytes. In addition, forced expression of ACBP, ALBP, and KLBP in CV-1 cells resulted in a substantial accumulation of all three proteins in the nucleus. These results suggest that lipid-binding proteins, contrary to the general assumption, may exert their action in the nucleus as well as in the cytoplasm.

Lysophosphatidic acid as a lipid mediator with multiple biological actions.

PubMed

Aikawa, Shizu; Hashimoto, Takafumi; Kano, Kuniyuki; Aoki, Junken

2015-02-01

Lysophosphatidic acid (LPA) is one of the simplest glycerophospholipids with one fatty acid chain and a phosphate group as a polar head. Although LPA had been viewed just as a metabolic intermediate in de novo lipid synthetic pathways, it has recently been paid much attention as a lipid mediator. LPA exerts many kinds of cellular processes, such as cell proliferation and smooth muscle contraction, through cognate G protein-coupled receptors. Because lipids are not coded by the genome directly, it is difficult to know their patho- and physiological roles. However, recent studies have identified several key factors mediating the biological roles of LPA, such as receptors and producing enzymes. In addition, studies of transgenic and gene knockout animals for these LPA-related genes, have revealed the biological significance of LPA. In this review we will summarize recent advances in the studies of LPA production and its roles in both physiological and pathological conditions. © The Authors 2014. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Stimuli responsive charge-switchable lipids: Capture and release of nucleic acids.

PubMed

Hersey, Joseph S; LaManna, Caroline M; Lusic, Hrvoje; Grinstaff, Mark W

2016-03-01

Stimuli responsive lipids, which enable control over the formation, transformation, and disruption of supramolecular assemblies, are of interest for biosensing, diagnostics, drug delivery, and basic transmembrane protein studies. In particular, spatiotemporal control over a supramolecular structure can be achieved using light activated compounds to induce significant supramolecular rearrangements. As such, a family of cationic lipids are described which undergo a permanent switch in charge upon exposure to 365 nm ultraviolet (UV) light to enable the capture of negatively charged nucleic acids within the self-assembled supramolecular structure of the lipids and subsequent release of these macromolecules upon exposure to UV light and disruption of the assemblies. The lipids are composed of either two different tripeptide head groups, Lysine-Glycine-Glycine (KGG) and Glycine-Glycine-Glycine (GGG) and three different hydrocarbon chain lengths (C6, C10, or C14) terminated by a UV light responsive 1-(2-nitrophenyl)ethanol (NPE) protected carboxylic acid. The photolysis of the NPE protected lipid is measured as a function of time, and the resulting changes in net molecular charge are observed using zeta potential analysis for each head group and chain length combination. A proof of concept study for the capture and release of both linear DNA (calf thymus) and siRNA is presented using an ethidium bromide quenching assay where a balance between binding affinity and supramolecular stability are found to be the key to optimal nucleic acid capture and release. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Curvature Forces in Membrane Lipid-Protein Interactions

PubMed Central

Brown, Michael F.

2012-01-01

Membrane biochemists are becoming increasingly aware of the role of lipid-protein interactions in diverse cellular functions. This review describes how conformational changes of membrane proteins—involving folding, stability, and membrane shape transitions—potentially involve elastic remodeling of the lipid bilayer. Evidence suggests that membrane lipids affect proteins through interactions of a relatively long-range nature, extending beyond a single annulus of next-neighbor boundary lipids. It is assumed the distance scale of the forces is large compared to the molecular range of action. Application of the theory of elasticity to flexible soft surfaces derives from classical physics, and explains the polymorphism of both detergents and membrane phospholipids. A flexible surface model (FSM) describes the balance of curvature and hydrophobic forces in lipid-protein interactions. Chemically nonspecific properties of the lipid bilayer modulate the conformational energetics of membrane proteins. The new biomembrane model challenges the standard model (the fluid mosaic model) found in biochemistry texts. The idea of a curvature force field based on data first introduced for rhodopsin gives a bridge between theory and experiment. Influences of bilayer thickness, nonlamellar-forming lipids, detergents, and osmotic stress are all explained by the FSM. An increased awareness of curvature forces suggests that research will accelerate as structural biology becomes more closely entwined with the physical chemistry of lipids in explaining membrane structure and function. PMID:23163284

Role of adipocyte lipid-binding protein (ALBP) and acyl-coA binding protein (ACBP) in PPAR-mediated transactivation.

PubMed

Helledie, Torben; Jørgensen, Claus; Antonius, Marianne; Krogsdam, Ann M; Kratchmarova, Irina; Kristiansen, Karsten; Mandrup, Susanne

2002-10-01

Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that are activated by a number of fatty acids and fatty acid derivatives. By contrast, we have recently shown that acyl-CoA esters display PPAR antagonistic properties in vitro. We have also shown that the adipocyte lipid binding protein (ALBP), the keratinocyte lipid binding protein (KLBP) and the acyl-CoA binding protein (ACBP) exhibit a prominent nuclear localization in differentiating 3T3-L1 adipocytes. Similarly, ectopic expression of these proteins in CV-1 cells resulted in a primarily nuclear localization. We therefore speculated that FABPs and ACBP might regulate the availability of PPAR agonists and antagonists by affecting not only their esterification in the cytoplasm but also their transport to and availability in the nucleus. We show here that coexpression of ALBP or ACBP exerts a negative effect on ligand-dependent PPAR transactivation, when tetradecylthioacetic (TTA) is used as ligand but not when the thiazolidinedione BRL49653 is used as ligand. The results presented here do not support the hypothesis that ALBP facilitates the transport of the fatty acid-type ligands to the nucleus, rather ALBP appears to sequester or increase the turn-over of the agonist. Similarly, our results are in keeping with a model in which ACBP increase the metabolism of these ligands.

Oleic Acid enhances all-trans retinoic Acid loading in nano-lipid emulsions.

PubMed

Chinsriwongkul, Akhayachatra; Opanasopit, Praneet; Ngawhirunpat, Tanasait; Rojanarata, Theerasak; Sila-On, Warisada; Ruktanonchai, Uracha

2010-01-01

The aim of this study was to investigate the enhancement of all-trans retinoic acid (ATRA) loading in nano-lipid emulsions and stability by using oleic acid. The effect of formulation factors including initial ATRA concentration and the type of oil on the physicochemical properties, that is, percentage yield, percentage drug release, and photostability of formulations, was determined. The solubility of ATRA was increased in the order of oleic acid > MCT > soybean oil > water. The physicochemical properties of ATRA-loaded lipid emulsion, including mean particle diameter and zeta potential, were modulated by changing an initial ATRA concentration as well as the type and mixing ratio of oil and oleic acid as an oil phase. The particles of lipid emulsions had average sizes of less than 250 nm and negative zeta potential. The addition of oleic acid in lipid emulsions resulted in high loading capacity. The photodegradation rate was found to be dependent on the initial drug concentration but independent of the type of oily phase used in this study. The release rates were not affected by initial ATRA concentration but were affected by the type of oil, where oleic acid showed the highest release rate of ATRA from lipid emulsions.

Polyunsaturated Fatty Acids in Lipid Bilayers and Tubules

NASA Astrophysics Data System (ADS)

Hirst, Linda S.; Yuan, Jing; Pramudya, Yohannes; Nguyen, Lam T.

2007-03-01

Omega-3 polyunsaturated fatty acids (PUFAs) are found in a variety of biological membranes and have been implicated with lipid raft formation and possible function, typical molecules include DHA (Docosahexanoic Acid) and AA (Alphalinoleic Acid) which have been the focus of considerable attention in recent years. We are interested in the phase behavior of these molecules in the lipid bilayer. The addition of lipid molecules with polyunsaturated chains has a clear effect on the fluidity and curvature of the membrane and we investigate the effects the addition of polyunsaturated lipids on bilayer structure and tubule formation. Self-assembled cylindrical lipid tubules have attracted considerable attention because of their interesting structures and potential technological applications. Using x-ray diffraction techniques, Atomic Force Microscopy and confocal fluorescence imaging, both symmetric and mixed chain lipids were incorporated into model membranes and the effects on bilayer structure and tubule formation investigated.

Lipoic acid functionalized amino acids cationic lipids as gene vectors.

PubMed

Su, Rong-Chuan; Liu, Qiang; Yi, Wen-Jing; Zheng, Li-Ting; Zhao, Zhi-Gang

2016-10-01

A series of reducible cationic lipids 4a-4f with different amino acid polar-head groups were prepared. The novel lipid contains a hydrophobic lipoic acid (LA) moiety, which can be reduced under reductive conditions to release of the encapsulated plasmid DNA. The particle size, zeta potential and cellular uptake of lipoplexes formed with DNA, as well as the transfection efficacy (TE) were characterized. The TE of the cationic lipid based on arginine was especially high, and was 2.5times higher than that of a branched polyethylenimine in the presence of 10% serum. Copyright © 2016 Elsevier Ltd. All rights reserved.

Critical Comparison of Biomembrane Force Fields: Protein-Lipid Interactions at the Membrane Interface.

PubMed

Sandoval-Perez, Angelica; Pluhackova, Kristyna; Böckmann, Rainer A

2017-05-09

Molecular dynamics (MD) simulations offer the possibility to study biological processes at high spatial and temporal resolution often not reachable by experiments. Corresponding biomolecular force field parameters have been developed for a wide variety of molecules ranging from inorganic ligands and small organic molecules over proteins and lipids to nucleic acids. Force fields have typically been parametrized and validated on thermodynamic observables and structural characteristics of individual compounds, e.g. of soluble proteins or lipid bilayers. Less strictly, due to the added complexity and missing experimental data to compare to, force fields have hardly been tested on the properties of mixed systems, e.g. on protein-lipid systems. Their selection and combination for mixed systems is further complicated by the partially differing parametrization strategies. Additionally, the presence of other compounds in the system may shift the subtle balance of force field parameters. Here, we assessed the protein-lipid interactions as described in the four atomistic force fields GROMOS54a7, CHARMM36 and the two force field combinations Amber14sb/Slipids and Amber14sb/Lipid14. Four observables were compared, focusing on the membrane-water interface: the conservation of the secondary structure of transmembrane proteins, the positioning of transmembrane peptides relative to the lipid bilayer, the insertion depth of side chains of unfolded peptides absorbed at the membrane interface, and the ability to reproduce experimental insertion energies of Wimley-White peptides at the membrane interface. Significant differences between the force fields were observed that affect e.g. membrane insertion depths and tilting of transmembrane peptides.

Lipid vesicle-mediated affinity chromatography using magnetic activated cell sorting (LIMACS): a novel method to analyze protein-lipid interaction.

PubMed

Bieberich, Erhard

2011-04-26

The analysis of lipid protein interaction is difficult because lipids are embedded in cell membranes and therefore, inaccessible to most purification procedures. As an alternative, lipids can be coated on flat surfaces as used for lipid ELISA and Plasmon resonance spectroscopy. However, surface coating lipids do not form microdomain structures, which may be important for the lipid binding properties. Further, these methods do not allow for the purification of larger amounts of proteins binding to their target lipids. To overcome these limitations of testing lipid protein interaction and to purify lipid binding proteins we developed a novel method termed lipid vesicle-mediated affinity chromatography using magnetic-activated cell sorting (LIMACS). In this method, lipid vesicles are prepared with the target lipid and phosphatidylserine as the anchor lipid for Annexin V MACS. Phosphatidylserine is a ubiquitous cell membrane phospholipid that shows high affinity to the protein Annexin V. Using magnetic beads conjugated to Annexin V the phosphatidylserine-containing lipid vesicles will bind to the magnetic beads. When the lipid vesicles are incubated with a cell lysate the protein binding to the target lipid will also be bound to the beads and can be co-purified using MACS. This method can also be used to test if recombinant proteins reconstitute a protein complex binding to the target lipid. We have used this method to show the interaction of atypical PKC (aPKC) with the sphingolipid ceramide and to co-purify prostate apoptosis response 4 (PAR-4), a protein binding to ceramide-associated aPKC. We have also used this method for the reconstitution of a ceramide-associated complex of recombinant aPKC with the cell polarity-related proteins Par6 and Cdc42. Since lipid vesicles can be prepared with a variety of sphingo- or phospholipids, LIMACS offers a versatile test for lipid-protein interaction in a lipid environment that resembles closely that of the cell membrane

Lipid and protein accumulation in developing seeds of three lupine species: Lupinus luteus L., Lupinus albus L., and Lupinus mutabilis Sweet.

PubMed

Borek, Slawomir; Pukacka, Stanisława; Michalski, Krzysztof; Ratajczak, Lech

2009-01-01

A comparative study was carried out on the dynamics of lipid accumulation in developing seeds of three lupine species. Lupine seeds differ in lipid content; yellow lupine (Lupinus luteus L.) seeds contain about 6%, white lupine (Lupinus albus L.) 7-14%, and Andean lupine (Lupinus mutabilis Sweet) about 20% of lipids by dry mass. Cotyledons from developing seeds were isolated and cultured in vitro for 96 h on Heller medium with 60 mM sucrose (+S) or without sucrose (-S). Each medium was additionally enriched with 35 mM asparagine or 35 mM NaNO3. Asparagine caused an increase in protein accumulation and simultaneously decreased the lipid content, but nitrate increased accumulation of both protein and lipid. Experiments with [1-14C]acetate and [2-14C]acetate showed that the decrease in lipid accumulation in developing lupine seeds resulted from exhaustion of lipid precursors rather than from degradation or modification of the enzymatic apparatus. The carbon atom from the C-1 position of acetate was liberated mainly as CO2, whereas the carbon atom from the C-2 position was preferentially used in anabolic pathways. The dominant phospholipid in the investigated lupine seed storage organs was phosphatidylcholine. The main fatty acid in yellow lupine cotyledons was linoleic acid, in white lupine it was oleic acid, and in Andean lupine it was both linoleic and oleic acids. The relationship between stimulation of lipid and protein accumulation by nitrate in developing lupine cotyledons and enhanced carbon flux through glycolysis caused by the inorganic nitrogen form is discussed.

Lipid content and fatty acid profile during lake whitefish embryonic development at different incubation temperatures.

PubMed

Mueller, Casey A; Doyle, Liam; Eme, John; Manzon, Richard G; Somers, Christopher M; Boreham, Douglas R; Wilson, Joanna Y

2017-01-01

Lipids serve as energy sources, structural components, and signaling molecules during fish embryonic development, and utilization of lipids may vary with temperature. Embryonic energy utilization under different temperatures is an important area of research in light of the changing global climate. Therefore, we examined percent lipid content and fatty acid profiles of lake whitefish (Coregonus clupeaformis) throughout embryonic development at three incubation temperatures. We sampled fertilized eggs and embryos at gastrulation, eyed and fin flutter stages following chronic incubation at temperatures of 1.8, 4.9 and 8.0°C. Hatchlings were also sampled following incubation at temperatures of 3.3, 4.9 and 8.0°C. Fertilized eggs had an initial high percentage of dry mass composed of lipid (percent lipid content; ~29%) consisting of ~20% saturated fatty acids (SFA), ~32% monounsaturated fatty acids (MUFA), ~44% polyunsaturated fatty acids (PUFA), and 4% unidentified. The most abundant fatty acids were 16:0, 16:1, 18:1(n-9c), 20:4(n-6), 20:5(n-3) and 22:6(n-3). This lipid profile matches that of other cold-water fish species. Percent lipid content increased during embryonic development, suggesting protein or other yolk components were preferentially used for energy. Total percentage of MUFA decreased during development, which indicated MUFA were the primary lipid catabolized for energy during embryonic development. Total percentage of PUFA increased during development, driven largely by an increase in 22:6(n-3). Temperature did not influence percent lipid content or percent MUFA at any development stage, and had inconsistent effects on percent SFA and percent PUFA during development. Thus, lake whitefish embryos appear to be highly adapted to low temperatures, and do not alter lipids in response to temperature within their natural incubation conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

Amino Acid Degradations Produced by Lipid Oxidation Products.

PubMed

Hidalgo, Francisco J; Zamora, Rosario

2016-06-10

Differently to amino acid degradations produced by carbohydrate-derived reactive carbonyls, amino acid degradations produced by lipid oxidation products are lesser known in spite of being lipid oxidation a major source of reactive carbonyls in food. This article analyzes the conversion of amino acids into Strecker aldehydes, α-keto acids, and amines produced by lipid-derived free radicals and carbonyl compounds, as well as the role of lipid oxidation products on the reactions suffered by these compounds: the formation of Strecker aldehydes and other aldehydes from α-keto acids; the formation of Strecker aldehydes and olefins from amines; the formation of shorter aldehydes from Strecker aldehydes; and the addition reactions suffered by the olefins produced from the amines. The relationships among all these reactions and the effect of reaction conditions on them are discussed. This knowledge should contribute to better control food processing in order to favor the formation of desirable beneficial compounds and to inhibit the production of compounds with deleterious properties.

Dietary fish protein hydrolysates containing bioactive motifs affect serum and adipose tissue fatty acid compositions, serum lipids, postprandial glucose regulation and growth in obese Zucker fa/fa rats.

PubMed

Drotningsvik, Aslaug; Mjøs, Svein A; Pampanin, Daniela M; Slizyte, Rasa; Carvajal, Ana; Remman, Tore; Høgøy, Ingmar; Gudbrandsen, Oddrun A

2016-10-01

The world's fisheries and aquaculture industries produce vast amounts of protein-containing by-products that can be enzymatically hydrolysed to smaller peptides and possibly be used as additives to functional foods and nutraceuticals targeted for patients with obesity-related metabolic disorders. To investigate the effects of fish protein hydrolysates on markers of metabolic disorders, obese Zucker fa/fa rats consumed diets with 75 % of protein from casein/whey (CAS) and 25 % from herring (HER) or salmon (SAL) protein hydrolysate from rest raw material, or 100 % protein from CAS for 4 weeks. The fatty acid compositions were similar in the experimental diets, and none of them contained any long-chain n-3 PUFA. Ratios of lysine:arginine and methionine:glycine were lower in HER and SAL diets when compared with CAS, and taurine was detected only in fish protein hydrolysate diets. Motifs with reported hypocholesterolemic or antidiabetic activities were identified in both fish protein hydrolysates. Rats fed HER diet had lower serum HDL-cholesterol and LDL-cholesterol, and higher serum TAG, MUFA and n-3:n-6 PUFA ratio compared with CAS-fed rats. SAL rats gained more weight and had better postprandial glucose regulation compared with CAS rats. Serum lipids and fatty acids were only marginally affected by SAL, but adipose tissue contained less total SFA and more total n-3 PUFA when compared with CAS. To conclude, diets containing hydrolysed rest raw material from herring or salmon proteins may affect growth, lipid metabolism, postprandial glucose regulation and fatty acid composition in serum and adipose tissue in obese Zucker rats.

The adaptor protein alpha-syntrophin regulates adipocyte lipid droplet growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisinger, Kristina; Rein-Fischboeck, Lisa; Pohl, Rebekka

The scaffold protein alpha-syntrophin (SNTA) regulates lipolysis indicating a role in lipid homeostasis. Adipocytes are the main lipid storage cells in the body, and here, the function of SNTA has been analyzed in 3T3-L1 cells. SNTA is expressed in preadipocytes and is induced early during adipogenesis. Knock-down of SNTA in preadipocytes increases their proliferation. Proteins which are induced during adipogenesis like adiponectin and caveolin-1, and the inflammatory cytokine IL-6 are at normal levels in the mature cells differentiated from preadipocytes with low SNTA. This suggests that SNTA does neither affect differentiation nor inflammation. Expression of proteins with a role inmore » cholesterol and triglyceride homeostasis is unchanged. Consequently, basal and epinephrine induced lipolysis as well as insulin stimulated phosphorylation of Akt and ERK1/2 are normal. Importantly, adipocytes with low SNTA form smaller lipid droplets and store less triglycerides. Stearoyl-CoA reductase and MnSOD are reduced upon SNTA knock-down but do not contribute to lower lipid levels. Oleate uptake is even increased in cells with SNTA knock-down. In summary, current data show that SNTA is involved in the expansion of lipid droplets independent of adipogenesis. Enhanced preadipocyte proliferation and capacity to store surplus fatty acids may protect adipocytes with low SNTA from lipotoxicity in obesity. - Highlights: • Alpha-syntrophin (SNTA) is expressed in 3T3-L1adipocytes. • SNTA knock-down in preadipocytes has no effect on adipogenesis. • Mature 3T3-L1 differentiated from cells with low SNTA form small lipid droplets. • SCD1 and MnSOD are reduced in adipocytes with low SNTA. • SCD1 knock-down does not alter triglyceride levels.« less

Branched short-chain fatty acids modulate glucose and lipid metabolism in primary adipocytes

PubMed Central

Heimann, Emilia; Nyman, Margareta; Pålbrink, Ann-Ki; Lindkvist-Petersson, Karin; Degerman, Eva

2016-01-01

ABSTRACT Short-chain fatty acids (SCFAs), e.g. acetic acid, propionic acid and butyric acid, generated through colonic fermentation of dietary fibers, have been shown to reach the systemic circulation at micromolar concentrations. Moreover, SCFAs have been conferred anti-obesity properties in both animal models and human subjects. Branched SCFAs (BSCFAs), e.g., isobutyric and isovaleric acid, are generated by fermentation of branched amino acids, generated from undigested protein reaching colon. However, BSCFAs have been sparsely investigated when referring to effects on energy metabolism. Here we primarily investigate the effects of isobutyric acid and isovaleric acid on glucose and lipid metabolism in primary rat and human adipocytes. BSCFAs inhibited both cAMP-mediated lipolysis and insulin-stimulated de novo lipogenesis at 10 mM, whereas isobutyric acid potentiated insulin-stimulated glucose uptake by all concentrations (1, 3 and 10 mM) in rat adipocytes. For human adipocytes, only SCFAs inhibited lipolysis at 10 mM. In both in vitro models, BSCFAs and SCFAs reduced phosphorylation of hormone sensitive lipase, a rate limiting enzyme in lipolysis. In addition, BSCFAs and SCFAs, in contrast to insulin, inhibited lipolysis in the presence of wortmannin, a phosphatidylinositide 3-kinase inhibitor and OPC3911, a phosphodiesterase 3 inhibitor in rat adipocytes. Furthermore, BSCFAs and SCFAs reduced insulin-mediated phosphorylation of protein kinase B. To conclude, BSCFAs have effects on adipocyte lipid and glucose metabolism that can contribute to improved insulin sensitivity in individuals with disturbed metabolism. PMID:27994949

Engineering acyl carrier protein to enhance production of shortened fatty acids.

PubMed

Liu, Xueliang; Hicks, Wade M; Silver, Pamela A; Way, Jeffrey C

2016-01-01

The acyl carrier protein (ACP) is an essential and ubiquitous component of microbial synthesis of fatty acids, the natural precursor to biofuels. Natural fatty acids usually contain long chains of 16 or more carbon atoms. Shorter carbon chains, with increased fuel volatility, are desired for internal combustion engines. Engineering the length specificity of key proteins in fatty acid metabolism, such as ACP, may enable microbial synthesis of these shorter chain fatty acids. We constructed a homology model of the Synechococcus elongatus ACP, showing a hydrophobic pocket harboring the growing acyl chain. Amino acids within the pocket were mutated to increase steric hindrance to the acyl chain. Certain mutant ACPs, when over-expressed in Escherichia coli, increased the proportion of shorter chain lipids; I75 W and I75Y showed the strongest effects. Expression of I75 W and I75Y mutant ACPs also increased production of lauric acid in E. coli that expressed the C12-specific acyl-ACP thioesterase from Cuphea palustris. We engineered the specificity of the ACP, an essential protein of fatty acid metabolism, to alter the E. coli lipid pool and enhance production of medium-chain fatty acids as biofuel precursors. These results indicate that modification of ACP itself could be combined with enzymes affecting length specificity in fatty acid synthesis to enhance production of commodity chemicals based on fatty acids.

Protective Effects of Ferulic Acid on High Glucose-Induced Protein Glycation, Lipid Peroxidation, and Membrane Ion Pump Activity in Human Erythrocytes

PubMed Central

Sompong, Weerachat; Cheng, Henrique; Adisakwattana, Sirichai

2015-01-01

Ferulic acid (FA) is the ubiquitous phytochemical phenolic derivative of cinnamic acid. Experimental studies in diabetic models demonstrate that FA possesses multiple mechanisms of action associated with anti-hyperglycemic activity. The mechanism by which FA prevents diabetes-associated vascular damages remains unknown. The aim of study was to investigate the protective effects of FA on protein glycation, lipid peroxidation, membrane ion pump activity, and phosphatidylserine exposure in high glucose-exposed human erythrocytes. Our results demonstrated that FA (10-100 μM) significantly reduced the levels of glycated hemoglobin (HbA1c) whereas 0.1-100 μM concentrations inhibited lipid peroxidation in erythrocytes exposed to 45 mM glucose. This was associated with increased glucose consumption. High glucose treatment also caused a significant reduction in Na+/K+-ATPase activity in the erythrocyte plasma membrane which could be reversed by FA. Furthermore, we found that FA (0.1-100 μM) prevented high glucose-induced phosphatidylserine exposure. These findings provide insights into a novel mechanism of FA for the prevention of vascular dysfunction associated with diabetes. PMID:26053739

Influence of the lipid phase state and electrostatic surface potential on the conformations of a peripherally bound membrane protein.

PubMed

Decca, María B; Galassi, Vanesa V; Perduca, Massimiliano; Monaco, Hugo L; Montich, Guillermo G

2010-11-25

Avian liver bile acid-binding protein (L-BABP) binds peripherically to anionic lipid membranes. We previously showed that in the absence of added salt the binding to 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) occurs with changes in the secondary structure, the extent of which depends on the phase state of the lipid. In the present work, we used Fourier transform infrared spectroscopy to study the conformations of L-BABP bound to lipids with phosphoglycerol and phosphatidic acid polar head groups and with different transition temperatures in an aqueous medium with high ionic strength (0.1 M NaCl). When L-BABP was bound to the lipids with saturated acyl chains, DMPG, 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG), 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA), and 1,2-dilauroyl-sn-glycero-3-phosphate (DLPA), the conformation shifted from a native-like secondary structure to an unfolded state at the temperature of lipid chain melting. The protein was in the native-like conformation when it was bound to the unsaturated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) in the liquid-crystalline phase. We also measured the electrokinetic surface potential of POPG and DMPG vesicles in the gel and in the liquid-crystalline phase and the protein binding constant to these lipid membranes. We found a correlation indicating that protein unfolding in the interface was due to the increase in the electrostatic surface potential that occurs in the lipid phase transition.

Fatty acid profile of 25 alternative lipid feedstocks

USDA-ARS?s Scientific Manuscript database

This study reports the fatty acid profiles of 25 alternative lipid feedstocks for the production of bio-based fuels and chemicals. Lipids were extracted using hexane from oil-bearing seeds using a standard Soxhlet apparatus. Fatty acid profiles were measured using gas chromatography-flame ionization...

Lipid and protein accumulation in developing seeds of three lupine species: Lupinus luteus L., Lupinus albus L., and Lupinus mutabilis Sweet

PubMed Central

Borek, Sławomir; Pukacka, Stanisława; Michalski, Krzysztof; Ratajczak, Lech

2009-01-01

A comparative study was carried out on the dynamics of lipid accumulation in developing seeds of three lupine species. Lupine seeds differ in lipid content; yellow lupine (Lupinus luteus L.) seeds contain about 6%, white lupine (Lupinus albus L.) 7–14%, and Andean lupine (Lupinus mutabilis Sweet) about 20% of lipids by dry mass. Cotyledons from developing seeds were isolated and cultured in vitro for 96 h on Heller medium with 60 mM sucrose (+S) or without sucrose (–S). Each medium was additionally enriched with 35 mM asparagine or 35 mM NaNO3. Asparagine caused an increase in protein accumulation and simultaneously decreased the lipid content, but nitrate increased accumulation of both protein and lipid. Experiments with [1-14C]acetate and [2-14C]acetate showed that the decrease in lipid accumulation in developing lupine seeds resulted from exhaustion of lipid precursors rather than from degradation or modification of the enzymatic apparatus. The carbon atom from the C-1 position of acetate was liberated mainly as CO2, whereas the carbon atom from the C-2 position was preferentially used in anabolic pathways. The dominant phospholipid in the investigated lupine seed storage organs was phosphatidylcholine. The main fatty acid in yellow lupine cotyledons was linoleic acid, in white lupine it was oleic acid, and in Andean lupine it was both linoleic and oleic acids. The relationship between stimulation of lipid and protein accumulation by nitrate in developing lupine cotyledons and enhanced carbon flux through glycolysis caused by the inorganic nitrogen form is discussed. PMID:19635747

Effects of different biomass drying and lipid extraction methods on algal lipid yield, fatty acid profile, and biodiesel quality.

PubMed

Hussain, Javid; Liu, Yan; Lopes, Wilson A; Druzian, Janice I; Souza, Carolina O; Carvalho, Gilson C; Nascimento, Iracema A; Liao, Wei

2015-03-01

Three lipid extraction methods of hexane Soxhlet (Sox-Hex), Halim (HIP), and Bligh and Dyer (BD) were applied on freeze-dried (FD) and oven-dried (OD) Chlorella vulgaris biomass to evaluate their effects on lipid yield, fatty acid profile, and algal biodiesel quality. Among these three methods, HIP was the preferred one for C. vulgaris lipid recovery considering both extraction efficiency and solvent toxicity. It had the highest lipid yields of 20.0 and 22.0% on FD and OD biomass, respectively, with corresponding neutral lipid yields of 14.8 and 12.7%. The lipid profiling analysis showed that palmitic, oleic, linoleic, and α-linolenic acids were the major fatty acids in the algal lipids, and there were no significant differences on the amount of these acids between different drying and extraction methods. Correlative models applied to the fatty acid profiles concluded that high contents of palmitic and oleic acids in algal lipids contributed to balancing the ratio of saturated and unsaturated fatty acids and led to a high-quality algal biodiesel.

Tauroursodeoxycholic Acid Attenuates Lipid Accumulation in Endoplasmic Reticulum-Stressed Macrophages

PubMed Central

Hua, Yinan; Kandadi, Machender R.; Zhu, Meijun; Ren, Jun; Sreejayan, Nair

2011-01-01

Background/Aim Recent evidence suggests that endoplasmic reticulum (ER) stress provoked under diabetic conditions augments the expression of scavenger receptors on macrophages, promoting the uptake of oxidized low-density lipoprotein (ox-LDL) uptake and atherogenesis. The aim of the present study was to test the hypothesis that the chemical chaperone tauroursodeoxycholic acid (TUDCA) attenuates lipid accumulation in macrophages subjected to ER stress. Methods Cultured human macrophages were subjected to ER-stress by treating them with tunicamycin. Lipid-uptake by macrophages subjected to ER-stress in the presence or absence of TUDCA was assessed by oil red O staining and by assessing the cellular uptake of Dil-ox-LDL by fluorescence measurement. Protein levels and phosphorylation status of ER stress markers, insulin-signalling molecules and scavenger receptor were assessed by Western blotting. Results Treatment of cultured human macrophages with the ER-stressor tunicamycin caused an increase in the protein levels of CD-36, and augmentation of lipid-uptake both of which were inhibited by TUDCA. TUDCA-treatment inhibited tunicamycin-induced ER-stress as evidenced by the attenuation of phosphorylation of eukaryotic translation initiation factor-2α and glucose reactive protein-78. In addition, TUDCA improved insulin signaling in macrophages by augmenting Akt-phosphorylation and blunting c-Jun N-terminal kinase activity. Conclusion Inhibition of macrophage ER-stress may represent a potential strategy in preventing atherogenesis under diabetic conditions. PMID:19834331

Acid sphingomyelinase activity is regulated by membrane lipids and facilitates cholesterol transfer by NPC2.

PubMed

Oninla, Vincent O; Breiden, Bernadette; Babalola, Jonathan O; Sandhoff, Konrad

2014-12-01

During endocytosis, membrane components move to intraluminal vesicles of the endolysosomal compartment for digestion. At the late endosomes, cholesterol is sorted out mainly by two sterol-binding proteins, Niemann-Pick protein type C (NPC)1 and NPC2. To study the NPC2-mediated intervesicular cholesterol transfer, we developed a liposomal assay system. (Abdul-Hammed, M., B. Breiden, M. A. Adebayo, J. O. Babalola, G. Schwarzmann, and K. Sandhoff. 2010. Role of endosomal membrane lipids and NPC2 in cholesterol transfer and membrane fusion. J. Lipid Res. 51: 1747-1760.) Anionic lipids stimulate cholesterol transfer between liposomes while SM inhibits it, even in the presence of anionic bis(monoacylglycero)phosphate (BMP). Preincubation of vesicles containing SM with acid sphingomyelinase (ASM) (SM phosphodiesterase, EC 3.1.4.12) results in hydrolysis of SM to ceramide (Cer), which enhances cholesterol transfer. Besides SM, ASM also cleaves liposomal phosphatidylcholine. Anionic phospholipids derived from the plasma membrane (phosphatidylglycerol and phosphatidic acid) stimulate SM and phosphatidylcholine hydrolysis by ASM more effectively than BMP, which is generated during endocytosis. ASM-mediated hydrolysis of liposomal SM was also stimulated by incorporation of diacylglycerol (DAG), Cer, and free fatty acids into the liposomal membranes. Conversely, phosphatidylcholine hydrolysis was inhibited by incorporation of cholesterol, Cer, DAG, monoacylglycerol, and fatty acids. Our data suggest that SM degradation by ASM is required for physiological secretion of cholesterol from the late endosomal compartment, and is a key regulator of endolysosomal lipid digestion. Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc.

Effect of brown seaweed lipids on fatty acid composition and lipid hydroperoxide levels of mouse liver.

PubMed

Airanthi, M K Widjaja-Adhi; Sasaki, Naoya; Iwasaki, Sayaka; Baba, Nobuko; Abe, Masayuki; Hosokawa, Masashi; Miyashita, Kazuo

2011-04-27

Brown seaweed lipids from Undaria pinnatifida (Wakame), Sargassum horneri (Akamoku), and Cystoseira hakodatensis (Uganomoku) contained several bioactive compounds, namely, fucoxanthin, polyphenols, and omega-3 polyunsaturated fatty acids (PUFA). Fucoxanthin and polyphenol contents of Akamoku and Uganomoku lipids were higher than those of Wakame lipids, while Wakame lipids showed higher total omega-3 PUFA content than Akamoku and Uganomoku lipids. The levels of docosahexaenoic acid (DHA) and arachidonic acid (AA) in liver lipids of KK-A(y) mouse significantly increased by Akamoku and Uganomoku lipid feeding as compared with the control, but not by Wakame lipid feeding. Fucoxanthin has been reported to accelerate the bioconversion of omega-3 PUFA and omega-6 PUFA to DHA and AA, respectively. The higher hepatic DHA and AA level of mice fed Akamoku and Uganomoku lipids would be attributed to the higher content of fucoxanthin of Akamoku and Uganomoku lipids. The lipid hydroperoxide levels of the liver of mice fed brown seaweed lipids were significantly lower than those of control mice, even though total PUFA content was higher in the liver of mice fed brown seaweed lipids. This would be, at least in part, due to the antioxidant activity of fucoxanthin metabolites in the liver.

Characterization of 3D Voronoi Tessellation Nearest Neighbor Lipid Shells Provides Atomistic Lipid Disruption Profile of Protein Containing Lipid Membranes

PubMed Central

Cheng, Sara Y.; Duong, Hai V.; Compton, Campbell; Vaughn, Mark W.; Nguyen, Hoa; Cheng, Kwan H.

2015-01-01

Quantifying protein-induced lipid disruptions at the atomistic level is a challenging problem in membrane biophysics. Here we propose a novel 3D Voronoi tessellation nearest-atom-neighbor shell method to classify and characterize lipid domains into discrete concentric lipid shells surrounding membrane proteins in structurally heterogeneous lipid membranes. This method needs only the coordinates of the system and is independent of force fields and simulation conditions. As a proof-of-principle, we use this multiple lipid shell method to analyze the lipid disruption profiles of three simulated membrane systems: phosphatidylcholine, phosphatidylcholine/cholesterol, and beta-amyloid/phosphatidylcholine/cholesterol. We observed different atomic volume disruption mechanisms due to cholesterol and beta-amyloid Additionally, several lipid fractional groups and lipid-interfacial water did not converge to their control values with increasing distance or shell order from the protein. This volume divergent behavior was confirmed by bilayer thickness and chain orientational order calculations. Our method can also be used to analyze high-resolution structural experimental data. PMID:25637891

Acid sphingomyelinase activity is regulated by membrane lipids and facilitates cholesterol transfer by NPC2[S

PubMed Central

Oninla, Vincent O.; Breiden, Bernadette; Babalola, Jonathan O.; Sandhoff, Konrad

2014-01-01

During endocytosis, membrane components move to intraluminal vesicles of the endolysosomal compartment for digestion. At the late endosomes, cholesterol is sorted out mainly by two sterol-binding proteins, Niemann-Pick protein type C (NPC)1 and NPC2. To study the NPC2-mediated intervesicular cholesterol transfer, we developed a liposomal assay system. (Abdul-Hammed, M., B. Breiden, M. A. Adebayo, J. O. Babalola, G. Schwarzmann, and K. Sandhoff. 2010. Role of endosomal membrane lipids and NPC2 in cholesterol transfer and membrane fusion. J. Lipid Res. 51: 1747–1760.) Anionic lipids stimulate cholesterol transfer between liposomes while SM inhibits it, even in the presence of anionic bis(monoacylglycero)phosphate (BMP). Preincubation of vesicles containing SM with acid sphingomyelinase (ASM) (SM phosphodiesterase, EC 3.1.4.12) results in hydrolysis of SM to ceramide (Cer), which enhances cholesterol transfer. Besides SM, ASM also cleaves liposomal phosphatidylcholine. Anionic phospholipids derived from the plasma membrane (phosphatidylglycerol and phosphatidic acid) stimulate SM and phosphatidylcholine hydrolysis by ASM more effectively than BMP, which is generated during endocytosis. ASM-mediated hydrolysis of liposomal SM was also stimulated by incorporation of diacylglycerol (DAG), Cer, and free fatty acids into the liposomal membranes. Conversely, phosphatidylcholine hydrolysis was inhibited by incorporation of cholesterol, Cer, DAG, monoacylglycerol, and fatty acids. Our data suggest that SM degradation by ASM is required for physiological secretion of cholesterol from the late endosomal compartment, and is a key regulator of endolysosomal lipid digestion. PMID:25339683

Intestinal-fatty acid binding protein and lipid transport in human intestinal epithelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montoudis, Alain; Delvin, Edgard; Canadian Institute of Health Research, Group of the Functional Development and Physiopathology of the Digestive Tract, and Department of Anatomy and Cellular Biology, Faculty of Medicine and Health Sciences, Universite de Sherbrooke, Sherbrooke, Que., Canada J1H 5N4

2006-01-06

Intestinal-fatty acid binding protein (I-FABP) is a 14-15 kDa cytoplasmic molecule highly expressed in the enterocyte. Although different functions have been proposed for various FABP family members, the specific function of I-FABP in human intestine remains unclear. Here, we studied the role of I-FABP in molecularly modified normal human intestinal epithelial cells (HIEC-6). cDNA transfection resulted in 90-fold I-FABP overexpression compared to cells treated with empty pQCXIP vector. The high-resolution immunogold technique revealed labeling mainly in the cytosol and confirmed the marked phenotype abundance of I-FABP in cDNA transfected cells. I-FABP overexpression was not associated with alterations in cell proliferationmore » and viability. Studies using these transfected cells cultured with [{sup 14}C]oleic acid did not reveal higher efficiency in de novo synthesis or secretion of triglycerides, phospholipids, and cholesteryl esters compared to cells treated with empty pQCXIP vector only. Similarly, the incubation with [{sup 35}S]methionine did not disclose a superiority in the biogenesis of apolipoproteins (apo) A-I, A-IV, B-48, and B-100. Finally, cells transfected with I-FABP did not exhibit an increased production of chylomicrons, VLDL, LDL, and HDL. Our observations establish that I-FABP overexpression in normal HIEC-6 is not related to cell proliferation, lipid esterification, apo synthesis, and lipoprotein assembly, and, therefore, exclude its role in intestinal fat transport.« less

Determining Membrane Protein-Lipid Binding Thermodynamics Using Native Mass Spectrometry.

PubMed

Cong, Xiao; Liu, Yang; Liu, Wen; Liang, Xiaowen; Russell, David H; Laganowsky, Arthur

2016-04-06

Membrane proteins are embedded in the biological membrane where the chemically diverse lipid environment can modulate their structure and function. However, the thermodynamics governing the molecular recognition and interaction of lipids with membrane proteins is poorly understood. Here, we report a method using native mass spectrometry (MS), to determine thermodynamics of individual ligand binding events to proteins. Unlike conventional methods, native MS can resolve individual ligand binding events and, coupled with an apparatus to control the temperature, determine binding thermodynamic parameters, such as for protein-lipid interactions. We validated our approach using three soluble protein-ligand systems (maltose binding protein, lysozyme, and nitrogen regulatory protein) and obtained similar results to those using isothermal titration calorimetry and surface plasmon resonance. We also determined for the first time the thermodynamics of individual lipid binding to the ammonia channel (AmtB), an integral membrane protein from Escherichia coli. Remarkably, we observed distinct thermodynamic signatures for the binding of different lipids and entropy-enthalpy compensation for binding lipids of variable chain length. Additionally, using a mutant form of AmtB that abolishes a specific phosphatidylglycerol (PG) binding site, we observed distinct changes in the thermodynamic signatures for binding PG, implying these signatures can identify key residues involved in specific lipid binding and potentially differentiate between specific lipid binding sites.

Solution Structure and Backbone Dynamics of Human Liver Fatty Acid Binding Protein: Fatty Acid Binding Revisited

PubMed Central

Cai, Jun; Lücke, Christian; Chen, Zhongjing; Qiao, Ye; Klimtchuk, Elena; Hamilton, James A.

2012-01-01

Liver fatty acid binding protein (L-FABP), a cytosolic protein most abundant in liver, is associated with intracellular transport of fatty acids, nuclear signaling, and regulation of intracellular lipolysis. Among the members of the intracellular lipid binding protein family, L-FABP is of particular interest as it can i), bind two fatty acid molecules simultaneously and ii), accommodate a variety of bulkier physiological ligands such as bilirubin and fatty acyl CoA. To better understand the promiscuous binding and transport properties of L-FABP, we investigated structure and dynamics of human L-FABP with and without bound ligands by means of heteronuclear NMR. The overall conformation of human L-FABP shows the typical β-clam motif. Binding of two oleic acid (OA) molecules does not alter the protein conformation substantially, but perturbs the chemical shift of certain backbone and side-chain protons that are involved in OA binding according to the structure of the human L-FABP/OA complex. Comparison of the human apo and holo L-FABP structures revealed no evidence for an “open-cap” conformation or a “swivel-back” mechanism of the K90 side chain upon ligand binding, as proposed for rat L-FABP. Instead, we postulate that the lipid binding process in L-FABP is associated with backbone dynamics. PMID:22713574

Genetically programmed expression of proteins containing the unnatural amino acid phenylselenocysteine

DOEpatents

Wang, Jiangyun; Schultz, Peter G.

2010-09-07

The invention relates to orthogonal pairs of tRNAs and aminoacyl-tRNA synthetases that can incorporate the unnatural amino acid phenylselenocysteine into proteins produced in eubacterial host cells such as E. coli. The invention provides, for example but not limited to, novel orthogonal aminoacyl-tRNA synthetases, polynucleotides encoding the novel synthetase molecules, methods for identifying and making the novel synthetases, methods for producing proteins containing the unnatural amino acid phenylselenocysteine and translation systems. The invention further provides methods for producing modified proteins (e.g., lipidated proteins) through targeted modification of the phenylselenocysteine residue in a protein.

Genetically programmed expression of proteins containing the unnatural amino acid phenylselenocysteine

DOEpatents

Wang, Jiangyun; Schultz, Peter G.

2012-07-10

The invention relates to orthogonal pairs of tRNAs and aminoacyl-tRNA synthetases that can incorporate the unnatural amino acid phenylselenocysteine into proteins produced in eubacterial host cells such as E. coli. The invention provides, for example but not limited to, novel orthogonal aminoacyl-tRNA synthetases, polynucleotides encoding the novel synthetase molecules, methods for identifying and making the novel synthetases, methods for producing proteins containing the unnatural amino acid phenylselenocysteine and translation systems. The invention further provides methods for producing modified proteins (e.g., lipidated proteins) through targeted modification of the phenylselenocysteine residue in a protein.

Intrinsic stability of Brassicaceae plasma membrane in relation to changes in proteins and lipids as a response to salinity.

PubMed

Chalbi, Najla; Martínez-Ballesta, Ma Carmen; Youssef, Nabil Ben; Carvajal, Micaela

2015-03-01

Changes in plasma membrane lipids, such as sterols and fatty acids, have been observed as a result of salt stress. These alterations, together with modification of the plasma membrane protein profile, confer changes in the physical properties of the membrane to be taken into account for biotechnological uses. In our experiments, the relationship between lipids and proteins in three different Brassicaceae species differing in salinity tolerance (Brassica oleracea, B. napus and Cakile maritima) and the final plasma membrane stability were studied. The observed changes in the sterol (mainly an increase in sitosterol) and fatty acid composition (increase in RUFA) in each species led to physical adaptation of the plasma membrane to salt stress. The in vitro vesicles stability was higher in the less tolerant (B. oleracea) plants together with low lipoxygenase activity. These results indicate that the proteins/lipids ratio and lipid composition is an important aspect to take into account for the use of natural vesicles in plant biotechnology. Copyright © 2014 Elsevier GmbH. All rights reserved.

Measuring protein-protein and protein-nucleic Acid interactions by biolayer interferometry.

PubMed

Sultana, Azmiri; Lee, Jeffrey E

2015-02-02

Biolayer interferometry (BLI) is a simple, optical dip-and-read system useful for measuring interactions between proteins, peptides, nucleic acids, small molecules, and/or lipids in real time. In BLI, a biomolecular bait is immobilized on a matrix at the tip of a fiber-optic sensor. The binding between the immobilized ligand and another molecule in an analyte solution produces a change in optical thickness at the tip and results in a wavelength shift proportional to binding. BLI provides direct binding affinities and rates of association and dissociation. This unit describes an efficient approach using streptavidin-based BLI to analyze DNA-protein and protein-protein interactions. A quantitative set of equilibrium binding affinities (K(d)) and rates of association and dissociation (k(a)/k(d)) can be measured in minutes using nanomole quantities of sample. Copyright © 2015 John Wiley & Sons, Inc.

The role of interfacial lipids in stabilizing membrane protein oligomers.

PubMed

Gupta, Kallol; Donlan, Joseph A C; Hopper, Jonathan T S; Uzdavinys, Povilas; Landreh, Michael; Struwe, Weston B; Drew, David; Baldwin, Andrew J; Stansfeld, Phillip J; Robinson, Carol V

2017-01-19

Oligomerization of membrane proteins in response to lipid binding has a critical role in many cell-signalling pathways but is often difficult to define or predict. Here we report the development of a mass spectrometry platform to determine simultaneously the presence of interfacial lipids and oligomeric stability and to uncover how lipids act as key regulators of membrane-protein association. Evaluation of oligomeric strength for a dataset of 125 α-helical oligomeric membrane proteins reveals an absence of interfacial lipids in the mass spectra of 12 membrane proteins with high oligomeric stability. For the bacterial homologue of the eukaryotic biogenic transporters (LeuT, one of the proteins with the lowest oligomeric stability), we found a precise cohort of lipids within the dimer interface. Delipidation, mutation of lipid-binding sites or expression in cardiolipin-deficient Escherichia coli abrogated dimer formation. Molecular dynamics simulation revealed that cardiolipin acts as a bidentate ligand, bridging across subunits. Subsequently, we show that for the Vibrio splendidus sugar transporter SemiSWEET, another protein with low oligomeric stability, cardiolipin shifts the equilibrium from monomer to functional dimer. We hypothesized that lipids are essential for dimerization of the Na + /H + antiporter NhaA from E. coli, which has the lowest oligomeric strength, but not for the substantially more stable homologous Thermus thermophilus protein NapA. We found that lipid binding is obligatory for dimerization of NhaA, whereas NapA has adapted to form an interface that is stable without lipids. Overall, by correlating interfacial strength with the presence of interfacial lipids, we provide a rationale for understanding the role of lipids in both transient and stable interactions within a range of α-helical membrane proteins, including G-protein-coupled receptors.

Bacillus subtilis Lipid Extract, A Branched-Chain Fatty Acid Model Membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nickels, Jonathan D.; Chatterjee, Sneha; Mostofian, Barmak

Lipid extracts are an excellent choice of model biomembrane; however at present, there are no commercially available lipid extracts or computational models that mimic microbial membranes containing the branched-chain fatty acids found in many pathogenic and industrially relevant bacteria. Here, we advance the extract of Bacillus subtilis as a standard model for these diverse systems, providing a detailed experimental description and equilibrated atomistic bilayer model included as Supporting Information to this Letter and at (http://cmb.ornl.gov/members/cheng). The development and validation of this model represents an advance that enables more realistic simulations and experiments on bacterial membranes and reconstituted bacterial membrane proteins.

Adipocyte Fatty Acid Binding Protein Potentiates Toxic Lipids-Induced Endoplasmic Reticulum Stress in Macrophages via Inhibition of Janus Kinase 2-dependent Autophagy

PubMed Central

Hoo, Ruby L. C.; Shu, Lingling; Cheng, Kenneth K. Y.; Wu, Xiaoping; Liao, Boya; Wu, Donghai; Zhou, Zhiguang; Xu, Aimin

2017-01-01

Lipotoxicity is implicated in the pathogenesis of obesity-related inflammatory complications by promoting macrophage infiltration and activation. Endoplasmic reticulum (ER) stress and adipocyte fatty acid binding protein (A-FABP) play key roles in obesity and mediate inflammatory activity through similar signaling pathways. However, little is known about their interplay in lipid-induced inflammatory responses. Here, we showed that prolonged treatment of palmitic acid (PA) increased ER stress and expression of A-FABP, which was accompanied by reduced autophagic flux in macrophages. Over-expression of A-FABP impaired PA-induced autophagy associating with enhanced ER stress and pro-inflammatory cytokine production, while genetic ablation or pharmacological inhibition of A-FABP reversed the conditions. PA-induced expression of autophagy-related protein (Atg)7 was attenuated in A-FABP over-expressed macrophages, but was elevated in A-FABP-deficient macrophages. Mechanistically, A-FABP potentiated the effects of PA by inhibition of Janus Kinase (JAK)2 activity, thus diminished PA-induced Atg7 expression contributing to impaired autophagy and further augmentation of ER stress. These findings suggest that A-FABP acts as autophagy inhibitor to instigate toxic lipids-induced ER stress through inhibition of JAK2-dependent autophagy, which in turn triggers inflammatory responses in macrophages. A-FABP-JAK2 axis may represent an important pathological pathway contributing to obesity-related inflammatory diseases. PMID:28094778

Maternal diets deficient in folic acid and related methyl donors modify mechanisms associated with lipid metabolism in the fetal liver of the rat.

PubMed

McNeil, Christopher J; Hay, Susan M; Rucklidge, Garry J; Reid, Martin D; Duncan, Gary J; Rees, William D

2009-11-01

Previously we have examined the effects of diets deficient in folic acid ( - F) or folate deficient with low methionine and choline ( - F LM LC) on the relative abundance of soluble proteins in the liver of the pregnant rat. In the present study we report the corresponding changes in the fetal liver at day 21 of gestation. The abundance of eighteen proteins increased when dams were fed the - F diet. When dams were fed the - F LM LC diet, thirty-three proteins increased and eight decreased. Many of the differentially abundant proteins in the fetal liver could be classified into the same functional groups as those previously identified in the maternal liver, namely protein synthesis, metabolism, lipid metabolism and proteins associated with the cytoskeleton and endoplasmic reticulum. The pattern was consistent with reduced cell proliferation in the - F LM LC group but not in the - F group. Metabolic enzymes associated with lipid metabolism changed in both the - F and - F LM LC groups. The mRNA for carnitine palmitoyl transferase were up-regulated and CD36 (fatty acid translocase) down-regulated in the - F group, suggesting increased mitochondrial oxidation of fatty acids as an indirect response to altered maternal lipid metabolism. In the - F LM LC group the mRNA for acetyl CoA carboxylase was down-regulated, suggesting reduced fatty acid synthesis. The mRNA for transcriptional regulators including PPARalpha and sterol response element-binding protein-1c were unchanged. These results suggest that an adequate supply of folic acid and the related methyl donors may benefit fetal development directly by improving lipid metabolism in fetal as well as maternal tissues.

High folic acid consumption leads to pseudo-MTHFR deficiency, altered lipid metabolism, and liver injury in mice.

PubMed

Christensen, Karen E; Mikael, Leonie G; Leung, Kit-Yi; Lévesque, Nancy; Deng, Liyuan; Wu, Qing; Malysheva, Olga V; Best, Ana; Caudill, Marie A; Greene, Nicholas D E; Rozen, Rima

2015-03-01

Increased consumption of folic acid is prevalent, leading to concerns about negative consequences. The effects of folic acid on the liver, the primary organ for folate metabolism, are largely unknown. Methylenetetrahydrofolate reductase (MTHFR) provides methyl donors for S-adenosylmethionine (SAM) synthesis and methylation reactions. Our goal was to investigate the impact of high folic acid intake on liver disease and methyl metabolism. Folic acid-supplemented diet (FASD, 10-fold higher than recommended) and control diet were fed to male Mthfr(+/+) and Mthfr(+/-) mice for 6 mo to assess gene-nutrient interactions. Liver pathology, folate and choline metabolites, and gene expression in folate and lipid pathways were examined. Liver and spleen weights were higher and hematologic profiles were altered in FASD-fed mice. Liver histology revealed unusually large, degenerating cells in FASD Mthfr(+/-) mice, consistent with nonalcoholic fatty liver disease. High folic acid inhibited MTHFR activity in vitro, and MTHFR protein was reduced in FASD-fed mice. 5-Methyltetrahydrofolate, SAM, and SAM/S-adenosylhomocysteine ratios were lower in FASD and Mthfr(+/-) livers. Choline metabolites, including phosphatidylcholine, were reduced due to genotype and/or diet in an attempt to restore methylation capacity through choline/betaine-dependent SAM synthesis. Expression changes in genes of one-carbon and lipid metabolism were particularly significant in FASD Mthfr(+/-) mice. The latter changes, which included higher nuclear sterol regulatory element-binding protein 1, higher Srepb2 messenger RNA (mRNA), lower farnesoid X receptor (Nr1h4) mRNA, and lower Cyp7a1 mRNA, would lead to greater lipogenesis and reduced cholesterol catabolism into bile. We suggest that high folic acid consumption reduces MTHFR protein and activity levels, creating a pseudo-MTHFR deficiency. This deficiency results in hepatocyte degeneration, suggesting a 2-hit mechanism whereby mutant hepatocytes cannot

Electron paramagnetic resonance study of lipid and protein membrane components of erythrocytes oxidized with hydrogen peroxide

PubMed Central

Mendanha, S.A.; Anjos, J.L.V.; Silva, A.H.M.; Alonso, A.

2012-01-01

Electron paramagnetic resonance (EPR) spectroscopy of spin labels was used to monitor membrane dynamic changes in erythrocytes subjected to oxidative stress with hydrogen peroxide (H2O2). The lipid spin label, 5-doxyl stearic acid, responded to dramatic reductions in membrane fluidity, which was correlated with increases in the protein content of the membrane. Membrane rigidity, associated with the binding of hemoglobin (Hb) to the erythrocyte membrane, was also indicated by a spin-labeled maleimide, 5-MSL, covalently bound to the sulfhydryl groups of membrane proteins. At 2% hematocrit, these alterations in membrane occurred at very low concentrations of H2O2 (50 µM) after only 5 min of incubation at 37°C in azide phosphate buffer, pH 7.4. Lipid peroxidation, suggested by oxidative hemolysis and malondialdehyde formation, started at 300 µM H2O2 (for incubation of 3 h), which is a concentration about six times higher than those detected with the probes. Ascorbic acid and α-tocopherol protected the membrane against lipoperoxidation, but did not prevent the binding of proteins to the erythrocyte membrane. Moreover, the antioxidant (+)-catechin, which also failed to prevent the cross-linking of cytoskeletal proteins with Hb, was very effective in protecting erythrocyte ghosts from lipid peroxidation induced by the Fenton reaction. This study also showed that EPR spectroscopy can be useful to assess the molecular dynamics of red blood cell membranes in both the lipid and protein domains and examine oxidation processes in a system that is so vulnerable to oxidation. PMID:22473321

Recombinant production and solution structure of lipid transfer protein from lentil Lens culinaris

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gizatullina, Albina K.; Moscow Institute of Physics and Technology; Finkina, Ekaterina I.

2013-10-04

Highlights: •Lipid transfer protein from lentil seeds (Lc-LTP2) was overexpressed in E. coli. •Antimicrobial activity and spatial structure of the recombinant Lc-LTP2 were examined. •Internal tunnel-like lipid-binding cavity occupies ∼7% of the total Lc-LTP2 volume. •Binding of DMPG lipid induces moderate rearrangements in the Lc-LTP2 structure. •Lc-LTP2/DMPG complex has limited lifetime and dissociates within tens of hours. -- Abstract: Lipid transfer protein, designated as Lc-LTP2, was isolated from seeds of the lentil Lens culinaris. The protein has molecular mass 9282.7 Da, consists of 93 amino acid residues including 8 cysteines forming 4 disulfide bonds. Lc-LTP2 and its stable isotope labeledmore » analogues were overexpressed in Escherichia coli and purified. Antimicrobial activity of the recombinant protein was examined, and its spatial structure was studied by NMR spectroscopy. The polypeptide chain of Lc-LTP2 forms four α-helices (Cys4-Leu18, Pro26-Ala37, Thr42-Ala56, Thr64-Lys73) and a long C-terminal tail without regular secondary structure. Side chains of the hydrophobic residues form a relatively large internal tunnel-like lipid-binding cavity (van der Waals volume comes up to ∼600 Å{sup 3}). The side-chains of Arg45, Pro79, and Tyr80 are located near an assumed mouth of the cavity. Titration with dimyristoyl phosphatidylglycerol (DMPG) revealed formation of the Lc-LTP2/lipid non-covalent complex accompanied by rearrangements in the protein spatial structure and expansion of the internal cavity. The resultant Lc-LTP2/DMPG complex demonstrates limited lifetime and dissociates within tens of hours.« less

The TULIP superfamily of eukaryotic lipid-binding proteins as a mediator of lipid sensing and transport.

PubMed

Alva, Vikram; Lupas, Andrei N

2016-08-01

The tubular lipid-binding (TULIP) superfamily has emerged in recent years as a major mediator of lipid sensing and transport in eukaryotes. It currently encompasses three protein families, SMP-like, BPI-like, and Takeout-like, which share a common fold. This fold consists of a long helix wrapped in a highly curved anti-parallel β-sheet, enclosing a central, lipophilic cavity. The SMP-like proteins, which include subunits of the ERMES complex and the extended synaptotagmins (E-Syts), appear to be mainly located at membrane contacts sites (MCSs) between organelles, mediating inter-organelle lipid exchange. The BPI-like proteins, which include the bactericidal/permeability-increasing protein (BPI), the LPS (lipopolysaccharide)-binding protein (LBP), the cholesteryl ester transfer protein (CETP), and the phospholipid transfer protein (PLTP), are either involved in innate immunity against bacteria through their ability to sense lipopolysaccharides, as is the case for BPI and LBP, or in lipid exchange between lipoprotein particles, as is the case for CETP and PLTP. The Takeout-like proteins, which are comprised of insect juvenile hormone-binding proteins and arthropod allergens, transport, where known, lipid hormones to target tissues during insect development. In all cases, the activity of these proteins is underpinned by their ability to bind large, hydrophobic ligands in their central cavity and segregate them away from the aqueous environment. Furthermore, where they are involved in lipid exchange, recent structural studies have highlighted their ability to establish lipophilic, tubular channels, either between organelles in the case of SMP domains or between lipoprotein particles in the case of CETP. Here, we review the current knowledge on the structure, versatile functions, and evolution of the TULIP superfamily. We propose a deep evolutionary split in this superfamily, predating the Last Eukaryotic Common Ancestor, between the SMP-like proteins, which act on

The Lipid Raft Proteome of African Trypanosomes Contains Many Flagellar Proteins.

PubMed

Sharma, Aabha I; Olson, Cheryl L; Engman, David M

2017-08-24

Lipid rafts are liquid-ordered membrane microdomains that form by preferential association of 3-β-hydroxysterols, sphingolipids and raft-associated proteins often having acyl modifications. We isolated lipid rafts of the protozoan parasite Trypanosoma brucei and determined the protein composition of lipid rafts in the cell. This analysis revealed a striking enrichment of flagellar proteins and several putative signaling proteins in the lipid raft proteome. Calpains and intraflagellar transport proteins, in particular, were found to be abundant in the lipid raft proteome. These findings provide additional evidence supporting the notion that the eukaryotic cilium/flagellum is a lipid raft-enriched specialized structure with high concentrations of sterols, sphingolipids and palmitoylated proteins involved in environmental sensing and cell signaling.

Permeability of lipid bilayers to amino acids and phosphate

NASA Technical Reports Server (NTRS)

Chakrabarti, A. C.; Deamer, D. W.

1992-01-01

Permeability coefficients for amino acid classes, including neutral, polar, hydrophobic, and charged species, were measured and compared with values for other ionic solutes such as phosphate. The rates of efflux of glycine, lysine, phenylalanine, serine and tryptophan were determined after they were passively entrapped in large unilamellar vesicles (LUVs) composed of egg phosphatidylcholine (EPC) or dimyristoylphosphatidylcholine (DMPC). The following permeability coefficients were obtained for: glycine, 5.7 x 10(-12) cm s-1 (EPC), 2.0 x 10(-11) cm s-1 (DMPC); serine, 5.5 x 10(-12) cm s-1 (EPC), 1.6 x 10(-11) cm s-1 (DMPC); lysine, 5.1 x 10(-12) cm s-1 (EPC), 1.9 x 10(-11) cm s-1 (DMPC); tryptophan, 4.1 x 10(-10) cm s-1 (EPC); and phenylalanine, 2.5 x 10(-10) cm s-1 (EPC). Decreasing lipid chain length increased permeability slightly, while variations in pH had only minor effects on the permeability coefficients of the amino acids tested. Phosphate permeability was in the range of 10(-12)-10(-13) cm s-1 depending on the pH of the medium. The values for the polar and charged amino acids were surprisingly similar to those previously measured for monovalent cations such as sodium and potassium, which are in the range of 10(-12)-10(-13) cm s-1, depending on conditions and the lipid species used. This observation suggests that the permeation rates for the neutral, polar and charged amino acids are controlled by bilayer fluctuations and transient defects, rather than partition coefficients and Born energy barriers. The results are relevant to the permeation of certain peptides into lipid bilayers during protein translocation and membrane biogenesis.

Lipid transfer particle from the silkworm, Bombyx mori, is a novel member of the apoB/large lipid transfer protein family[S

PubMed Central

Yokoyama, Hiroshi; Yokoyama, Takeru; Yuasa, Masashi; Fujimoto, Hirofumi; Sakudoh, Takashi; Honda, Naoko; Fugo, Hajime; Tsuchida, Kozo

2013-01-01

Lipid transfer particle (LTP) is a high-molecular-weight, very high-density lipoprotein known to catalyze the transfer of lipids between a variety of lipoproteins, including both insects and vertebrates. Studying the biosynthesis and regulation pathways of LTP in detail has not been possible due to a lack of information regarding the apoproteins. Here, we sequenced the cDNA and deduced amino acid sequences for three apoproteins of LTP from the silkworm (Bombyx mori). The three subunit proteins of the LTP are coded by two genes, apoLTP-II/I and apoLTP-III. ApoLTP-I and apoLTP-II are predicted to be generated by posttranslational cleavage of the precursor protein, apoLTP-II/I. Clusters of amphipathic secondary structure within apoLTP-II/I are similar to Homo sapiens apolipoprotein B (apoB) and insect lipophorins. The apoLTP-II/I gene is a novel member of the apoB/large lipid transfer protein gene family. ApoLTP-III has a putative conserved juvenile hormone-binding protein superfamily domain. Expression of apoLTP-II/I and apoLTP-III genes was synchronized and both genes were primarily expressed in the fat body at the stage corresponding to increased lipid transport needs. We are now in a position to study in detail the physiological role of LTP and its biosynthesis and assembly. PMID:23812557

Identification of novel phosphatidic acid-binding proteins in the rat brain.

PubMed

Park, ChiHu; Kang, Du-Seock; Shin, Geon-Hoon; Seo, Jeongkon; Kim, Hyein; Suh, Pann-Ghill; Bae, Chang-Dae; Shin, Joo-Ho

2015-05-19

Phosphatidic acid (PA) is an abundant negatively-charged phospholipid and has long been considered to be an important signaling molecule in diverse cellular events. Thus, the identification of proteins that specifically interact with PA is of considerable interest to understand the regulatory roles of PA. Herein, lipid-affinity purification and mass spectrometric analysis reveals 43 proteins, 19 known and 24 novel, as PA-binding proteins. A lipid-protein overlay assay confirmed that GDI1, PACSIN1, and DPYSL2 interact with not only with PA but also with other phospholipids. These results might be helpful for deciphering the functional effect of PA in the brain. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Prediction of glycolipid-binding domains from the amino acid sequence of lipid raft-associated proteins: application to HpaA, a protein involved in the adhesion of Helicobacter pylori to gastrointestinal cells.

PubMed

Fantini, Jacques; Garmy, Nicolas; Yahi, Nouara

2006-09-12

Protein-glycolipid interactions mediate the attachment of various pathogens to the host cell surface as well as the association of numerous cellular proteins with lipid rafts. Thus, it is of primary importance to identify the protein domains involved in glycolipid recognition. Using structure similarity searches, we could identify a common glycolipid-binding domain in the three-dimensional structure of several proteins known to interact with lipid rafts. Yet the three-dimensional structure of most raft-targeted proteins is still unknown. In the present study, we have identified a glycolipid-binding domain in the amino acid sequence of a bacterial adhesin (Helicobacter pylori adhesin A, HpaA). The prediction was based on the major properties of the glycolipid-binding domains previously characterized by structural searches. A short (15-mer) synthetic peptide corresponding to this putative glycolipid-binding domain was synthesized, and we studied its interaction with glycolipid monolayers at the air-water interface. The synthetic HpaA peptide recognized LacCer but not Gb3. This glycolipid specificity was in line with that of the whole bacterium. Molecular modeling studies gave some insights into this high selectivity of interaction. It also suggested that Phe147 in HpaA played a key role in LacCer recognition, through sugar-aromatic CH-pi stacking interactions with the hydrophobic side of the galactose ring of LacCer. Correspondingly, the replacement of Phe147 with Ala strongly affected LacCer recognition, whereas substitution with Trp did not. Our method could be used to identify glycolipid-binding domains in microbial and cellular proteins interacting with lipid shells, rafts, and other specialized membrane microdomains.

Ligand Binding Properties of the Lentil Lipid Transfer Protein: Molecular Insight into the Possible Mechanism of Lipid Uptake.

PubMed

Shenkarev, Zakhar O; Melnikova, Daria N; Finkina, Ekaterina I; Sukhanov, Stanislav V; Boldyrev, Ivan A; Gizatullina, Albina K; Mineev, Konstantin S; Arseniev, Alexander S; Ovchinnikova, Tatiana V

2017-03-28

The lentil lipid transfer protein, designated as Lc-LTP2, was isolated from Lens culinaris seeds. The protein belongs to the LTP1 subfamily and consists of 93 amino acid residues. Its spatial structure includes four α-helices (H1-H4) and a long C-terminal tail. Here, we report the ligand binding properties of Lc-LTP2. The fluorescent 2-p-toluidinonaphthalene-6-sulfonate binding assay revealed that the affinity of Lc-LTP2 for saturated and unsaturated fatty acids was enhanced with a decrease in acyl-chain length. Measurements of boundary potential in planar lipid bilayers and calcein dye leakage in vesicular systems revealed preferential interaction of Lc-LTP2 with the negatively charged membranes. Lc-LTP2 more efficiently transferred anionic dimyristoylphosphatidylglycerol (DMPG) than zwitterionic dimyristoylphosphatidylcholine. Nuclear magnetic resonance experiments confirmed the higher affinity of Lc-LTP2 for anionic lipids and those with smaller volumes of hydrophobic chains. The acyl chains of the bound lysopalmitoylphosphatidylglycerol (LPPG), DMPG, or dihexanoylphosphatidylcholine molecules occupied the internal hydrophobic cavity, while their headgroups protruded into the aqueous environment between helices H1 and H3. The spatial structure and backbone dynamics of the Lc-LTP2-LPPG complex were determined. The internal cavity was expanded from ∼600 to ∼1000 Å 3 upon the ligand binding. Another entrance into the internal cavity, restricted by the H2-H3 interhelical loop and C-terminal tail, appeared to be responsible for the attachment of Lc-LTP2 to the membrane or micelle surface and probably played an important role in the lipid uptake determining the ligand specificity. Our results confirmed the previous assumption regarding the membrane-mediated antimicrobial action of Lc-LTP2 and afforded molecular insight into its biological role in the plant.

Structural elucidation of the interaction between neurodegenerative disease-related tau protein with model lipid membranes

NASA Astrophysics Data System (ADS)

Jones, Emmalee M.

A protein's sequence of amino acids determines how it folds. That folded structure is linked to protein function, and misfolding to dysfunction. Protein misfolding and aggregation into beta-sheet rich fibrillar aggregates is connected with over 20 neurodegenerative diseases, including Alzheimer's disease (AD). AD is characterized in part by misfolding, aggregation and deposition of the microtubule associated tau protein into neurofibrillary tangles (NFTs). However, two questions remain: What is tau's fibrillization mechanism, and what is tau's cytotoxicity mechanism? Tau is prone to heterogeneous interactions, including with lipid membranes. Lipids have been found in NFTs, anionic lipid vesicles induced aggregation of the microtubule binding domain of tau, and other protein aggregates induced ion permeability in cells. This evidence prompted our investigation of tau's interaction with model lipid membranes to elucidate the structural perturbations those interactions induced in tau protein and in the membrane. We show that although tau is highly charged and soluble, it is highly surface active and preferentially interacts with anionic membranes. To resolve molecular-scale structural details of tau and model membranes, we utilized X-ray and neutron scattering techniques. X-ray reflectivity indicated tau aggregated at air/water and anionic lipid membrane interfaces and penetrated into membranes. More significantly, membrane interfaces induced tau protein to partially adopt a more compact conformation with density similar to folded protein and ordered structure characteristic of beta-sheet formation. This suggests possible membrane-based mechanisms of tau aggregation. Membrane morphological changes were seen using fluorescence microscopy, and X-ray scattering techniques showed tau completely disrupts anionic membranes, suggesting an aggregate-based cytotoxicity mechanism. Further investigation of protein constructs and a "hyperphosphorylation" disease mimic helped

Efficient delivery of genome-editing proteins using bioreducible lipid nanoparticles.

PubMed

Wang, Ming; Zuris, John A; Meng, Fantao; Rees, Holly; Sun, Shuo; Deng, Pu; Han, Yong; Gao, Xue; Pouli, Dimitra; Wu, Qi; Georgakoudi, Irene; Liu, David R; Xu, Qiaobing

2016-03-15

A central challenge to the development of protein-based therapeutics is the inefficiency of delivery of protein cargo across the mammalian cell membrane, including escape from endosomes. Here we report that combining bioreducible lipid nanoparticles with negatively supercharged Cre recombinase or anionic Cas9:single-guide (sg)RNA complexes drives the electrostatic assembly of nanoparticles that mediate potent protein delivery and genome editing. These bioreducible lipids efficiently deliver protein cargo into cells, facilitate the escape of protein from endosomes in response to the reductive intracellular environment, and direct protein to its intracellular target sites. The delivery of supercharged Cre protein and Cas9:sgRNA complexed with bioreducible lipids into cultured human cells enables gene recombination and genome editing with efficiencies greater than 70%. In addition, we demonstrate that these lipids are effective for functional protein delivery into mouse brain for gene recombination in vivo. Therefore, the integration of this bioreducible lipid platform with protein engineering has the potential to advance the therapeutic relevance of protein-based genome editing.

The Lipid Raft Proteome of African Trypanosomes Contains Many Flagellar Proteins

PubMed Central

Sharma, Aabha I.; Olson, Cheryl L.; Engman, David M.

2017-01-01

Lipid rafts are liquid-ordered membrane microdomains that form by preferential association of 3-β-hydroxysterols, sphingolipids and raft-associated proteins often having acyl modifications. We isolated lipid rafts of the protozoan parasite Trypanosoma brucei and determined the protein composition of lipid rafts in the cell. This analysis revealed a striking enrichment of flagellar proteins and several putative signaling proteins in the lipid raft proteome. Calpains and intraflagellar transport proteins, in particular, were found to be abundant in the lipid raft proteome. These findings provide additional evidence supporting the notion that the eukaryotic cilium/flagellum is a lipid raft-enriched specialized structure with high concentrations of sterols, sphingolipids and palmitoylated proteins involved in environmental sensing and cell signaling. PMID:28837104

Synergistic interactions of lipids and myelin basic protein

NASA Astrophysics Data System (ADS)

Hu, Yufang; Doudevski, Ivo; Wood, Denise; Moscarello, Mario; Husted, Cynthia; Genain, Claude; Zasadzinski, Joseph A.; Israelachvili, Jacob

2004-09-01

This report describes force measurements and atomic force microscope imaging of lipid-protein interactions that determine the structure of a model membrane system that closely mimics the myelin sheath. Our results suggest that noncovalent, mainly electrostatic and hydrophobic, interactions are responsible for the multilamellar structure and stability of myelin. We find that myelin basic protein acts as a lipid coupler between two apposed bilayers and as a lipid "hole-filler," effectively preventing defect holes from developing. From our protein-mediated-adhesion and force-distance measurements, we develop a simple quantitative model that gives a reasonably accurate picture of the molecular mechanism and adhesion of bilayer-bridging proteins by means of noncovalent interactions. The results and model indicate that optimum myelin adhesion and stability depend on the difference between, rather than the product of, the opposite charges on the lipid bilayers and myelin basic protein, as well as on the repulsive forces associated with membrane fluidity, and that small changes in any of these parameters away from the synergistically optimum values can lead to large changes in the adhesion or even its total elimination. Our results also show that the often-asked question of which membrane species, the lipids or the proteins, are the "important ones" may be misplaced. Both components work synergistically to provide the adhesion and overall structure. A better appreciation of the mechanism of this synergy may allow for a better understanding of stacked and especially myelin membrane structures and may lead to better treatments for demyelinating diseases such as multiple sclerosis. lipid-protein interactions | myelin membrane structure | membrane adhesion | membrane regeneration/healing | demyelinating diseases

Lipids and fatty acids in roasted chickens.

PubMed

Souza, S A; Visentainer, J V; Matsushita, M; Souza, N E

1999-09-01

Total lipids from meat portions of breast, thigh, wing, side and back with and without skin from 10 roasted chickens were extracted with chloroform and methanol and gravimetrically determined, and their fatty acids were analysed as methyl esters by gaseous chromatography, using a flame ionization detector and capillary column. The main fatty acids found were: C16:0, C18:1 omega 9, and C18:2 omega 6. The average ratio observed between PUFA/SFA was of 0.98, mainly due to the great concentration of the C18:2 omega 6 fatty acid, with an average of 26.75%. Regarding to the lipids content, the skinless breast showed the lowest content, 0.78 g/100 g, while the back with skin was the one with the highest content, 12.13 g/100 g except for the pure skin, with 26.54 grams of lipids by 100 grams.

Characterization and antifungal properties of wheat nonspecific lipid transfer proteins.

PubMed

Sun, Jin-Yue; Gaudet, Denis A; Lu, Zhen-Xiang; Frick, Michele; Puchalski, Byron; Laroche, André

2008-03-01

This study simultaneously considered the phylogeny, fatty acid binding ability, and fungal toxicity of a large number of monocot nonspecific lipid transfer proteins (ns-LTP). Nine novel full-length wheat ns-LTP1 clones, all possessing coding sequences of 348 bp, isolated from abiotic- and biotic-stressed cDNA libraries from aerial tissues, exhibited highly conserved coding regions with 78 to 99 and 71 to 100% identity at the nucleotide and amino acid levels, respectively. Phylogenetic analyses revealed two major ns-LTP families in wheat. Eight wheat ns-LTP genes from different clades were cloned into the expression vector pPICZalpha and transformed into Pichia pastoris. Sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blotting, and in vitro lipid binding activity assay confirmed that the eight ns-LTP were all successfully expressed and capable of in vitro binding fatty acid molecules. A comparative in vitro study on the toxicity of eight wheat ns-LTP to mycelium growth or spore germination of eight wheat pathogens and three nonwheat pathogens revealed differential toxicities among different ns-LTP. Values indicating 50% inhibition of fungal growth or spore germination of three selected ns-LTP against six fungi ranged from 1 to 7 microM. In vitro lipid-binding activity of ns-LTP was not correlated with their antifungal activity. Using the fluorescent probe SYTOX Green as an indicator of fungal membrane integrity, the in vitro toxicity of wheat ns-LTP was associated with alteration in permeability of fungal membranes.

Ribosomal protein-Mdm2-p53 pathway coordinates nutrient stress with lipid metabolism by regulating MCD and promoting fatty acid oxidation.

PubMed

Liu, Yong; He, Yizhou; Jin, Aiwen; Tikunov, Andrey P; Zhou, Lishi; Tollini, Laura A; Leslie, Patrick; Kim, Tae-Hyung; Li, Lei O; Coleman, Rosalind A; Gu, Zhennan; Chen, Yong Q; Macdonald, Jeffrey M; Graves, Lee M; Zhang, Yanping

2014-06-10

The tumor suppressor p53 has recently been shown to regulate energy metabolism through multiple mechanisms. However, the in vivo signaling pathways related to p53-mediated metabolic regulation remain largely uncharacterized. By using mice bearing a single amino acid substitution at cysteine residue 305 of mouse double minute 2 (Mdm2(C305F)), which renders Mdm2 deficient in binding ribosomal proteins (RPs) RPL11 and RPL5, we show that the RP-Mdm2-p53 signaling pathway is critical for sensing nutrient deprivation and maintaining liver lipid homeostasis. Although the Mdm2(C305F) mutation does not significantly affect growth and development in mice, this mutation promotes fat accumulation under normal feeding conditions and hepatosteatosis under acute fasting conditions. We show that nutrient deprivation inhibits rRNA biosynthesis, increases RP-Mdm2 interaction, and induces p53-mediated transactivation of malonyl-CoA decarboxylase (MCD), which catalyzes the degradation of malonyl-CoA to acetyl-CoA, thus modulating lipid partitioning. Fasted Mdm2(C305F) mice demonstrate attenuated MCD induction and enhanced malonyl-CoA accumulation in addition to decreased oxidative respiration and increased fatty acid accumulation in the liver. Thus, the RP-Mdm2-p53 pathway appears to function as an endogenous sensor responsible for stimulating fatty acid oxidation in response to nutrient depletion.

Lipid A binding proteins in macrophages detected by ligand blotting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hampton, R.Y.; Golenbock, D.T.; Raetz, C.R.H.

1987-05-01

Endotoxin (LPS) stimulates a variety of eukaryotic cells. These actions are involved in the pathogenesis of Gram-negative septicemia. The site of action of the LPS toxic moiety, lipid A (LA), is unclear. Their laboratory has previously identified a bioactive LA precursor lipid IV/sub A/, which can be enzymatically labeled with /sup 32/P/sub i/ (10/sup 9/ dpm/nmole) and purified (99%). They now show that this ligand binds to specific proteins immobilized on nitrocellulose (NC) from LPS-sensitive RAW 264.7 cultured macrophages. NC blots were incubated with (/sup 32/P)-IV/sub A/ in a buffer containing BSA, NaCl, polyethylene glycol, and azide. Binding was assessedmore » using autoradiography or scintillation counting. Dot blot binding of the radioligand was inhibited by excess cold IV/sub A/, LA, or ReLPS but not by phosphatidylcholine, cardiolipin, phosphatidylinositol, or phosphatidic acid. Binding was trypsin-sensitive and dependent on protein concentration. Particulate macrophage proteins were subjected to SDS-PAGE and then electroblotted onto NC. Several discrete binding proteins were observed. Identical treatment of fetal bovine serum or molecular weight standards revealed no detectable binding. By avoiding high nonspecific binding of intact membranes, this ligand blotting assay may be useful in elucidating the molecular actions of LPS.« less

Effect of pomegranate peel extract on lipid and protein oxidation in beef meatballs during refrigerated storage.

PubMed

Turgut, Sebahattin Serhat; Soyer, Ayla; Işıkçı, Fatma

2016-06-01

Antioxidant effect of pomegranate peel extract (PE) to retard lipid and protein oxidation was investigated in meatballs during refrigerated storage at 4±1°C. Concentrated lyophilised water extract of pomegranate peel was incorporated into freshly minced beef meat at 0.5% and 1% concentrations and compared with 0.01% butylated hydroxytoluene (BHT) as a reference and control (without any antioxidant). PE showed high phenolic content and antioxidant activity. In PE added samples, thiobarbituric acid reactive substances (TBARS) value, peroxide formation, loss of sulfhydryl groups and formation of protein carbonyls were lower than control (P<0.01) after 8 days of storage. Sensory evaluation with respect to colour and rancid odour revealed that PE incorporation in meatballs prolonged the refrigerated storage up to 8 days. Addition of both 0.5 and 1% PE in meatballs reduced lipid and protein oxidation and improved sensory scores. These results indicated that PE was effective on retarding lipid and protein oxidation. Copyright © 2016 Elsevier Ltd. All rights reserved.

A grape polyphenol extract modulates muscle membrane fatty acid composition and lipid metabolism in high-fat--high-sucrose diet-fed rats.

PubMed

Aoun, Manar; Michel, Francoise; Fouret, Gilles; Schlernitzauer, Audrey; Ollendorff, Vincent; Wrutniak-Cabello, Chantal; Cristol, Jean-Paul; Carbonneau, Marie-Annette; Coudray, Charles; Feillet-Coudray, Christine

2011-08-01

Accumulation of muscle TAG content and modification of muscle phospholipid fatty acid pattern may have an impact on lipid metabolism, increasing the risk of developing diabetes. Some polyphenols have been reported to modulate lipid metabolism, in particular those issued from red grapes. The present study was designed to determine whether a grape polyphenol extract (PPE) modulates skeletal muscle TAG content and phospholipid fatty acid composition in high-fat-high-sucrose (HFHS) diet-fed rats. Muscle plasmalemmal and mitochondrial fatty acid transporters, GLUT4 and lipid metabolism pathways were also explored. The PPE decreased muscle TAG content in HFHS/PPE diet-fed rats compared with HFHS diet-fed rats and induced higher proportions of n-3 PUFA in phospholipids. The PPE significantly up-regulated GLUT4 mRNA expression. Gene and protein expression of muscle fatty acid transporter cluster of differentiation 36 (CD36) was increased in HFHS diet-fed rats but returned to control values in HFHS/PPE diet-fed rats. Carnitine palmitoyltransferase 1 protein expression was decreased with the PPE. Mitochondrial β-hydroxyacyl CoA dehydrogenase was increased in HFHS diet-fed rats and returned to control values with PPE supplementation. Lipogenesis, mitochondrial biogenesis and mitochondrial activity were not affected by the PPE. In conclusion, the PPE modulated membrane phospholipid fatty acid composition and decreased muscle TAG content in HFHS diet-fed rats. The PPE lowered CD36 gene and protein expression, probably decreasing fatty acid transport and lipid accumulation within skeletal muscle, and increased muscle GLUT4 expression. These effects of the PPE are in favour of a better insulin sensibility.

The role of lipid composition for insertion and stabilization of amino acids in membranes

NASA Astrophysics Data System (ADS)

Johansson, Anna C. V.; Lindahl, Erik

2009-05-01

While most membrane protein helices are clearly hydrophobic, recent experiments have indicated that it is possible to insert marginally hydrophobic helices into bilayers and have suggested apparent in vivo free energies of insertion for charged residues that are low, e.g., a few kcals for arginine. In contrast, a number of biophysical simulation studies have predicted that the bilayer interior is close to a pure hydrophobic environment with large penalties for hydrophilic amino acids—and yet the experimental scales do significantly better at predicting actual membrane proteins from sequence. Here, we have systematically studied the dependence of the free energy profiles on lipid properties, including tail length, saturation, headgroup hydrogen bond strength, and charge, both to see to whether the in vivo insertion can be explained in whole or part from lipid composition of the endoplasmic reticulum (ER) membranes, and if the solvation properties can help interpret how protein function depends on the lipids. We find that lipid charge is important to stabilize charged amino acids inside the bilayer (with implications, e.g., for ion channels), that thicker bilayers have higher solvation costs for hydrophilic side chains, and that headgroup hydrogen bond strength determines how adaptive the lipids are as a hydrophobic/hydrophilic solvent. None of the different free energy profiles are even close to the low apparent in vivo insertion cost, which suggests that regardless of the specific ER membrane composition the current experimental results cannot be explained by normal lipid-type variation.

The role of interfacial lipids in stabilising membrane protein oligomers

PubMed Central

Uzdavinys, Povilas; Landreh, Michael; Struwe, Weston B.; Drew, David; Baldwin, Andrew J.; Stansfeld, Phillip J.; Robinson, Carol V.

2017-01-01

Oligomerisation of membrane proteins in response to lipid binding plays a critical role in many cell-signaling pathways 1 but is often difficult to define 2 or predict 3. Here we develop a mass spectrometry platform to determine simultaneously presence of interfacial lipids and oligomeric stability and discover how lipids act as key regulators of membrane protein association. Evaluation of oligomeric strength for a dataset of 125 α-helical oligomeric membrane proteins revealed an absence of interfacial lipids in the mass spectra of 12 membrane proteins with high oligomeric stability. For the bacterial homologue of the eukaryotic biogenic transporters (LeuT) 4 one of the proteins with the lowest oligomeric stability, we found a precise cohort of lipids within the dimer interface. Delipidation, mutation of lipid binding sites or expression in cardiolipin (CDL) deficient Escherichia coli, abrogated dimer formation. Molecular dynamics simulation revealed that CDL acts as a bidentate ligand bridging across subunits. Subsequently, we show that for the sugar transporter SemiSWEET from Vibrio splendidus 5, another protein with low oligomeric stability, cardiolipin shifts the equilibrium from monomer to functional dimer. We hypothesised that lipids would be essential for dimerisation of the Na+/H+ antiporter NhaA from E. coli, which has the lowest oligomeric strength, but not for substantially more stable, homologous NapA from Thermus thermophilus. We found that lipid binding is obligatory for dimerisation of NhaA, whereas NapA has adapted to form an interface that is stable without lipids. Overall, by correlating interfacial strength with the presence of interfacial lipids we provide a rationale for understanding the role of lipids in both transient and stable interactions within a range of α-helical membrane proteins, including GPCRs. PMID:28077870

Lipid and fatty acid analysis of the Plodia interpunctella granulosis virus (PiGV) envelope

NASA Technical Reports Server (NTRS)

Shastri-Bhalla, K.; Funk, C. J.; Consigli, R. A.; Spooner, B. S. (Principal Investigator)

1993-01-01

Virus envelope was isolated from Plodia interpunctella granulosis virus, produced in early fourth-instar larvae. Both polar and neutral lipids were analyzed by two-dimensional thin-layer chromatography. Fatty acid composition of various individual neutral and polar lipids was determined by gas-liquid chromatography. The major components of envelope neutral lipid were diacylglycerols. Palmitic acid and stearic acid were the major saturated fatty acids in both polar and neutral lipids. Whereas palmitoleic acid was the major unsaturated fatty acids in neutral lipids, oleic acid was the major unsaturated fatty acid in the polar lipids.

Simple, effective protein extraction method and proteomics analysis from polyunsaturated fatty acids-producing micro-organisms.

PubMed

Ling, Xueping; Guo, Jing; Zheng, Chuqiang; Ye, Chiming; Lu, Yinghua; Pan, Xueshan; Chen, Zhengqi; Ng, I-Son

2015-12-01

Polyunsaturated fatty acids (PUFAs) are valuable ingredients in the food and pharmaceutical products due to their beneficial influence on human health. Most studies paid attention on the production of PUFAs from oleaginous micro-organisms but seldom on the comparative proteomics of cells. In the study, three methods (i.e., cold shock, acetone precipitation and ethanol precipitation) for lipid removal from crude protein extracts were applied in different PUFAs-producing micro-organisms. Among the selective strains, Schizochytrium was used as an oleaginous strain with high lipid of 60.3 (w/w%) in biomass. The Mortierella alpina and Cunninghamella echinulata were chosen as the low-lipid-content strains with 25.8 (w/w%) and 21.8 (w/w%) of lipid in biomass, respectively. The cold shock resulted as the most effective method for lipid removed, thus obtained higher protein amount for Schizochytrium. Moreover, from the comparative proteomics for the three PUFAs-producing strains, it showed more significant proteins of up or down-regulation were explored under cold shock treatment. Therefore, the essential proteins (i.e., polyunsaturated fatty acid synthase) and regulating proteins were observed. In conclusion, this study provides a valuable and practical approach for analysis of high PUFAs-producing strains at the proteomics level, and would further accelerate the understanding of the metabolic flux in oleaginous micro-organisms.

Membrane proteins bind lipids selectively to modulate their structure and function.

PubMed

Laganowsky, Arthur; Reading, Eamonn; Allison, Timothy M; Ulmschneider, Martin B; Degiacomi, Matteo T; Baldwin, Andrew J; Robinson, Carol V

2014-06-05

Previous studies have established that the folding, structure and function of membrane proteins are influenced by their lipid environments and that lipids can bind to specific sites, for example, in potassium channels. Fundamental questions remain however regarding the extent of membrane protein selectivity towards lipids. Here we report a mass spectrometry approach designed to determine the selectivity of lipid binding to membrane protein complexes. We investigate the mechanosensitive channel of large conductance (MscL) from Mycobacterium tuberculosis and aquaporin Z (AqpZ) and the ammonia channel (AmtB) from Escherichia coli, using ion mobility mass spectrometry (IM-MS), which reports gas-phase collision cross-sections. We demonstrate that folded conformations of membrane protein complexes can exist in the gas phase. By resolving lipid-bound states, we then rank bound lipids on the basis of their ability to resist gas phase unfolding and thereby stabilize membrane protein structure. Lipids bind non-selectively and with high avidity to MscL, all imparting comparable stability; however, the highest-ranking lipid is phosphatidylinositol phosphate, in line with its proposed functional role in mechanosensation. AqpZ is also stabilized by many lipids, with cardiolipin imparting the most significant resistance to unfolding. Subsequently, through functional assays we show that cardiolipin modulates AqpZ function. Similar experiments identify AmtB as being highly selective for phosphatidylglycerol, prompting us to obtain an X-ray structure in this lipid membrane-like environment. The 2.3 Å resolution structure, when compared with others obtained without lipid bound, reveals distinct conformational changes that re-position AmtB residues to interact with the lipid bilayer. Our results demonstrate that resistance to unfolding correlates with specific lipid-binding events, enabling a distinction to be made between lipids that merely bind from those that modulate membrane

Lipid transfer proteins in the assembly of apoB-containing lipoproteins.

PubMed

Sirwi, Alaa; Hussain, M Mahmood

2018-04-12

A better understanding of intracellular lipoprotein assembly may help identify proteins with important roles in lipid disorders. ApoB-containing lipoproteins are macromolecular lipid and protein micelles that act as specialized transport vehicles for hydrophobic lipids. They are assembled predominantly in enterocytes and hepatocytes to transport dietary and endogenous fat, respectively, to different tissues. Assembly occurs in the endoplasmic reticulum and is dependent on lipid re-synthesis in the endoplasmic reticulum and on a chaperone, namely microsomal triglyceride transfer protein. Precursors for lipid synthesis are obtained from extracellular sources and from cytoplasmic lipid droplets. Microsomal triglyceride transfer protein is the major and essential lipid transfer protein that transfers phospholipids and triacylglycerols to nascent apoB for the assembly of lipoproteins. Assembly is aided by cell death-inducing DFF45-like effector B and by phospholipid transfer protein, which may facilitate additional deposition of triacylglycerols and phospholipids, respectively, to apoB. Here, we summarize the current understanding of the different steps in the assembly of apoB-containing lipoproteins and discuss the role of lipid transfer proteins in these steps to help identify new clinical targets for lipid-associated disorders, such as heart disease. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Localization of a portion of the liver isoform of fatty-acid-binding protein (L-FABP) to peroxisomes

PubMed Central

Antonenkov, Vasily D.; Sormunen, Raija T.; Ohlmeier, Steffen; Amery, Leen; Fransen, Marc; Mannaerts, Guy P.; Hiltunen, J. Kalervo

2005-01-01

The liver isoform of fatty-acid-binding protein (L-FABP) facilitates the cellular uptake, transport and metabolism of fatty acids and is also involved in the regulation of gene expressions and cell differentiation. Consistent with these functions, L-FABP is predominantly present in the cytoplasm and to a lesser extent in the nucleus; however, a significant portion of this protein has also been detected in fractions containing different organelles. More recent observations, notably on L-FABP-deficient mice, indicated a possible direct involvement of L-FABP in the peroxisomal oxidation of long-chain fatty acids. In order to clarify the links between L-FABP and peroxisomal lipid metabolism, we reinvestigated the subcellular distribution of the protein. Analytical subcellular fractionation by a method preserving the intactness of isolated peroxisomes, two-dimensional gel electrophoresis of peroxisomal matrix proteins combined with MS analysis, and immunoelectron microscopy of liver sections demonstrate the presence of L-FABP in the matrix of peroxisomes as a soluble protein. Peroxisomal L-FABP was highly inducible by clofibrate. The induction of L-FABP was accompanied by a marked increase in the binding capacity of peroxisomal matrix proteins for oleic acid and cis-parinaric acid. The peroxisomal β-oxidation of palmitoyl-CoA and acyl-CoA thioesterase activity were stimulated by L-FABP, indicating that the protein modulates the function of peroxisomal lipid-metabolizing enzymes. The possible role of intraperoxisomal L-FABP in lipid metabolism is discussed. PMID:16262600

Localization of a portion of the liver isoform of fatty-acid-binding protein (L-FABP) to peroxisomes.

PubMed

Antonenkov, Vasily D; Sormunen, Raija T; Ohlmeier, Steffen; Amery, Leen; Fransen, Marc; Mannaerts, Guy P; Hiltunen, J Kalervo

2006-03-01

The liver isoform of fatty-acid-binding protein (L-FABP) facilitates the cellular uptake, transport and metabolism of fatty acids and is also involved in the regulation of gene expressions and cell differentiation. Consistent with these functions, L-FABP is predominantly present in the cytoplasm and to a lesser extent in the nucleus; however, a significant portion of this protein has also been detected in fractions containing different organelles. More recent observations, notably on L-FABP-deficient mice, indicated a possible direct involvement of L-FABP in the peroxisomal oxidation of long-chain fatty acids. In order to clarify the links between L-FABP and peroxisomal lipid metabolism, we reinvestigated the subcellular distribution of the protein. Analytical subcellular fractionation by a method preserving the intactness of isolated peroxisomes, two-dimensional gel electrophoresis of peroxisomal matrix proteins combined with MS analysis, and immunoelectron microscopy of liver sections demonstrate the presence of L-FABP in the matrix of peroxisomes as a soluble protein. Peroxisomal L-FABP was highly inducible by clofibrate. The induction of L-FABP was accompanied by a marked increase in the binding capacity of peroxisomal matrix proteins for oleic acid and cis-parinaric acid. The peroxisomal beta-oxidation of palmitoyl-CoA and acyl-CoA thioesterase activity were stimulated by L-FABP, indicating that the protein modulates the function of peroxisomal lipid-metabolizing enzymes. The possible role of intraperoxisomal L-FABP in lipid metabolism is discussed.

Identification of the bile acid-binding site of the ileal lipid-binding protein by photoaffinity labeling, matrix-assisted laser desorption ionization-mass spectrometry, and NMR structure.

PubMed

Kramer, W; Sauber, K; Baringhaus, K H; Kurz, M; Stengelin, S; Lange, G; Corsiero, D; Girbig, F; König, W; Weyland, C

2001-03-09

The ileal lipid-binding protein (ILBP) is the only physiologically relevant bile acid-binding protein in the cytosol of ileocytes. To identify the bile acid-binding site(s) of ILBP, recombinant rabbit ILBP photolabeled with 3-azi- and 7-azi-derivatives of cholyltaurine was analyzed by a combination of enzymatic fragmentation, gel electrophoresis, and matrix-assisted laser desorption ionization (MALDI)-mass spectrometry. The attachment site of the 3-position of cholyltaurine was localized to the amino acid triplet His(100)-Thr(101)-Ser(102) using the photoreactive 3,3-azo-derivative of cholyltaurine. With the corresponding 7,7-azo-derivative, the attachment point of the 7-position could be localized to the C-terminal part (position 112-128) as well as to the N-terminal part suggesting more than one binding site for bile acids. By chemical modification and NMR structure of ILBP, arginine residue 122 was identified as the probable contact point for the negatively charged side chain of cholyltaurine. Consequently, bile acids bind to ILBP with the steroid nucleus deep inside the protein cavity and the negatively charged side chain near the entry portal. The combination of photoaffinity labeling, enzymatic fragmentation, MALDI-mass spectrometry, and NMR structure was successfully used to determine the topology of bile acid binding to ILBP.

A comparative study of the fatty acid composition of prochloron lipids

NASA Technical Reports Server (NTRS)

Kenrick, J. R.; Deane, E. M.; Bishop, D. G.

1983-01-01

The chemical analysis of lipids of Prochloron isolated from several hosts is discussed. The object was to determine whether differences in lipid composition could be used to characterize organisms from different sources. Major lipid components are given. An analysis of fatty acid composition of individual lipids slowed a distinctive disstribution of fatty acids. While present results do not justify the use of fatty acid content in the taxonomy of Prochlon, the variations found in the lipids of cells from the same host harvested from different areas, or at different times in the same area, suggest that a study of the effects of temperature and light intensity on lipid composition would be rewarding.

The peritumoural adipose tissue microenvironment and cancer. The roles of fatty acid binding protein 4 and fatty acid binding protein 5.

PubMed

Guaita-Esteruelas, S; Gumà, J; Masana, L; Borràs, J

2018-02-15

The adipose tissue microenvironment plays a key role in tumour initiation and progression because it provides fatty acids and adipokines to tumour cells. The fatty acid-binding protein (FABP) family is a group of small proteins that act as intracellular fatty acid transporters. Adipose-derived FABPs include FABP4 and FABP5. Both have an important role in lipid-related metabolic processes and overexpressed in many cancers, such as breast, prostate, colorectal and ovarian. Moreover, their expression in peritumoural adipose tissue is deregulated, and their circulating levels are upregulated in some tumours. In this review, we discuss the role of the peritumoural adipose tissue and the related adipokines FABP4 and FABP5 in cancer initiation and progression and the possible pathways implicated in these processes. Copyright © 2017 Elsevier B.V. All rights reserved.

Lipid-protein interaction induced domains: Kinetics and conformational changes in multicomponent vesicles

NASA Astrophysics Data System (ADS)

Sreeja, K. K.; Sunil Kumar, P. B.

2018-04-01

The spatio-temporal organization of proteins and the associated morphological changes in membranes are of importance in cell signaling. Several mechanisms that promote the aggregation of proteins at low cell surface concentrations have been investigated in the past. We show, using Monte Carlo simulations, that the affinity of proteins for specific lipids can hasten their aggregation kinetics. The lipid membrane is modeled as a dynamically triangulated surface with the proteins defined as in-plane fields at the vertices. We show that, even at low protein concentrations, strong lipid-protein interactions can result in large protein clusters indicating a route to lipid mediated signal amplification. At high protein concentrations, the domains form buds similar to that seen in lipid-lipid interaction induced phase separation. Protein interaction induced domain budding is suppressed when proteins act as anisotropic inclusions and exhibit nematic orientational order. The kinetics of protein clustering and resulting conformational changes are shown to be significantly different for the isotropic and anisotropic curvature inducing proteins.

Spectral analysis of light emitted during the oxidation of lipids and proteins

NASA Astrophysics Data System (ADS)

Turrens, Julio F.; Robinson, Eric; Freeman, Scott; George, Benedict F., III

2003-05-01

Oxidative stress is associated with a variety of pathological processes of clinical relevance. Some of the intermediates generated during the chain reactions associated with oxidation of lipids and proteins are electronically excited and decay emitting photons, which may be detected with the help of sensitive photomultipliers. This technique has been used to monitor oxidative stress in a variety of scenarios including intact organs in vivo or in vitro, and simple models such as proteins and lipids exposed to oxidants. The main drawback of this technique is that the emission of light is extremely weak and it is subjected to substantial interference from spurious sources. In addition, the quantum efficiency of photomultipliers varies with wavelength making it even more difficult to collect reliable data using photomultipliers sensitive to relatively broad spectral ranges. In order to identify the peak emission wavelengths in the visible region, we exposed model systems (proteins, lipids and amino acids) to peroxynitrite and sources of hydroxyl and alcoxyl radicals, analyzing the emission of light with interference filters. The results indicate that the peak emission for most biological models occurs between 450 and 700 nm. The emission at higher wavelengths (lower energy levels) was observed mostly in the presence of less powerful oxidants such as tert-butyl hydroperoxide.

Influence of omega-3 polyunsaturated fatty acids from fish oil or meal on the structure of lipid microdomains in bovine luteal cells.

PubMed

Plewes, M R; Burns, P D; Graham, P E; Bruemmer, J E; Engle, T E

2018-06-01

Biological membranes are composed of a lipid bilayer and proteins that form lipid microdomains. This study examined the effects of fish byproducts on lipid-protein interactions within lipid microdomains of bovine luteal cells. In Exp. 1 and 2, luteal cells were prepared from corpora lutea (CL; n = 4 to 8) collected at an abattoir. Exp. 1 was conducted to optimize ultrasonication in a detergent-free protocol for isolation of lipid microdomains. A power setting of 10 to 20% was effective in isolating lipid microdomains from bulk lipid. In Exp. 2, cells were cultured in control medium or fish oil to determine influence of fish oil on distribution of lipid microdomain markers and prostaglandin F 2α (FP) receptors. Cells treated with fish oil had a smaller percentage of microdomain markers and FP receptor in microdomains (P < 0.05). In Exp. 3 and 4, cells were prepared from mid-cycle CL obtained from cows supplemented with corn gluten meal (n = 4) or fish meal (n = 4). Exp. 3 examined effects of dietary supplementation on distribution of lipid microdomain markers and FP receptor and Exp. 4 on fatty acid composition within lipid microdomains. A smaller percentage of lipid microdomain markers and FP receptor was detected in microdomains of cells collected from fish meal supplemented animals (P < 0.05). In Exp. 4, a greater percentage of omega-3 polyunsaturated fatty acids was detected in bulk lipid from fish meal supplemented cows (P < 0.05). Results show that fish byproducts influence lipid-protein interactions in lipid microdomains in bovine luteal cells. Copyright © 2018 Elsevier B.V. All rights reserved.

SLDP: a novel protein related to caleosin is associated with the endosymbiotic Symbiodinium lipid droplets from Euphyllia glabrescens.

PubMed

Pasaribu, Buntora; Lin, I-Ping; Tzen, Jason T C; Jauh, Guang-Yuh; Fan, Tung-Yung; Ju, Yu-Min; Cheng, Jing-O; Chen, Chii-Shiarng; Jiang, Pei-Luen

2014-10-01

Intracellular lipid droplets (LDs) have been proposed to play a key role in the mutualistic endosymbiosis between reef-building corals and the dinoflagellate endosymbiont Symbiodinium spp. This study investigates and identifies LD proteins in Symbiodinium from Euphyllia glabrescens. Discontinuous Percoll gradient centrifugation was used to separate Symbiodinium cells from E. glabrescens tentacles. Furthermore, staining with a fluorescent probe, Nile red, indicated that lipids accumulated in that freshly isolated Symbiodinium cells and lipid analyses further showed polyunsaturated fatty acids (PUFA) was abundant. The stable LDs were purified from endosymbiotic Symbiodinium cells. The structural integrity of the Symbiodinium LDs was maintained via electronegative repulsion and steric hindrance possibly provided by their surface proteins. Protein extracts from the purified LDs revealed a major protein band with a molecular weight of 20 kDa, which was termed Symbiodinium lipid droplet protein (SLDP). Interestingly, immunological cross-recognition analysis revealed that SLDP was detected strongly by the anti-sesame and anti-cycad caleosin antibodies. It was suggested that the stable Symbiodinium LDs were sheltered by this unique structural protein and was suggested that SLDP might be homologous to caleosin to a certain extent.

Lipid droplet-associated proteins in high-fat fed mice with the effects of voluntary running and diet change.

PubMed

Rinnankoski-Tuikka, Rita; Hulmi, Juha J; Torvinen, Sira; Silvennoinen, Mika; Lehti, Maarit; Kivelä, Riikka; Reunanen, Hilkka; Kujala, Urho M; Kainulainen, Heikki

2014-08-01

The relation between lipid accumulation and influence of exercise on insulin sensitivity is not straightforward. A proper balance between lipid droplet synthesis, lipolysis, and oxidative metabolism would ensure low local intramyocellular fatty acid levels, thereby possibly protecting against lipotoxicity-associated insulin resistance. This study investigated whether the accumulation of triglycerides and lipid droplets in response to high availability of fatty acids after high-fat feeding would parallel the abundance of intramyocellular perilipin proteins, especially PLIN5. The effects on these variables after diet change or voluntary running exercise intervention in skeletal muscle were also investigated. During a 19-week experiment, C57BL/6J mice were studied in six different groups: low-fat diet sedentary, low-fat diet active, high-fat diet sedentary, high-fat diet active and two groups which were high-fat sedentary for nine weeks, after which divided into low-fat sedentary or low-fat active groups. Myocellular triglyceride concentration and perilipin protein expression levels were assessed. We show that, concurrently with impaired insulin sensitivity, the expression level of PLIN5 and muscular triglyceride concentration increased dramatically after high-fat diet. These adaptations were reversible after the diet change intervention with no additional effect of exercise. After high-fat diet, lipid droplets become larger providing more surface area for PLIN5. We suggest that PLIN5 is an important regulator of lipid droplet turnover in altered conditions of fatty acid supply and consumption. Imbalances in lipid droplet metabolism and turnover might lead to lipotoxicity-related insulin resistance. Copyright © 2014 Elsevier Inc. All rights reserved.

Immunomodulatory lipids in plants: plant fatty acid amides and the human endocannabinoid system.

PubMed

Gertsch, Jürg

2008-05-01

Since the discovery that endogenous lipid mediators show similar cannabimimetic effects as phytocannabinoids from CANNABIS SATIVA, our knowledge about the endocannabinoid system has rapidly expanded. Today, endocannabinoid action is known to be involved in various diseases, including inflammation and pain. As a consequence, the G-protein coupled cannabinoid receptors, endocannabinoid transport, as well as endocannabinoid metabolizing enzymes represent targets to block or enhance cannabinoid receptor-mediated signalling for therapeutic intervention. Based on the finding that certain endocannabinoid-like fatty acid N-alkylamides from purple coneflower ( ECHINACEA spp.) potently activate CB2 cannabinoid receptors we have focused our interest on plant fatty acid amides (FAAs) and their overall cannabinomodulatory effects. Certain FAAs are also able to partially inhibit the action of fatty acid amide hydrolase (FAAH), which controls the breakdown of endocannabinoids. Intriguingly, plants lack CB receptors and do not synthesize endocannabinoids, but express FAAH homologues capable of metabolizing plant endogenous N-acylethanolamines (NAEs). While the site of action of these NAEs in plants is unknown, endogenous NAEs and arachidonic acid glycerols in animals interact with distinct physiological lipid receptors, including cannabinoid receptors. There is increasing evidence that also plant FAAs other than NAEs can pharmacologically modulate the action of these endogenous lipid signals. The interference of plant FAAs with the animal endocannabinoid system could thus be a fortunate evolutionary cross point with yet unexplored therapeutic potential.

High folic acid consumption leads to pseudo-MTHFR deficiency, altered lipid metabolism, and liver injury in mice12345

PubMed Central

Christensen, Karen E; Mikael, Leonie G; Leung, Kit-Yi; Lévesque, Nancy; Deng, Liyuan; Wu, Qing; Malysheva, Olga V; Best, Ana; Caudill, Marie A; Greene, Nicholas DE

2015-01-01

Background: Increased consumption of folic acid is prevalent, leading to concerns about negative consequences. The effects of folic acid on the liver, the primary organ for folate metabolism, are largely unknown. Methylenetetrahydrofolate reductase (MTHFR) provides methyl donors for S-adenosylmethionine (SAM) synthesis and methylation reactions. Objective: Our goal was to investigate the impact of high folic acid intake on liver disease and methyl metabolism. Design: Folic acid–supplemented diet (FASD, 10-fold higher than recommended) and control diet were fed to male Mthfr+/+ and Mthfr+/− mice for 6 mo to assess gene-nutrient interactions. Liver pathology, folate and choline metabolites, and gene expression in folate and lipid pathways were examined. Results: Liver and spleen weights were higher and hematologic profiles were altered in FASD-fed mice. Liver histology revealed unusually large, degenerating cells in FASD Mthfr+/− mice, consistent with nonalcoholic fatty liver disease. High folic acid inhibited MTHFR activity in vitro, and MTHFR protein was reduced in FASD-fed mice. 5-Methyltetrahydrofolate, SAM, and SAM/S-adenosylhomocysteine ratios were lower in FASD and Mthfr+/− livers. Choline metabolites, including phosphatidylcholine, were reduced due to genotype and/or diet in an attempt to restore methylation capacity through choline/betaine-dependent SAM synthesis. Expression changes in genes of one-carbon and lipid metabolism were particularly significant in FASD Mthfr+/− mice. The latter changes, which included higher nuclear sterol regulatory element-binding protein 1, higher Srepb2 messenger RNA (mRNA), lower farnesoid X receptor (Nr1h4) mRNA, and lower Cyp7a1 mRNA, would lead to greater lipogenesis and reduced cholesterol catabolism into bile. Conclusions: We suggest that high folic acid consumption reduces MTHFR protein and activity levels, creating a pseudo-MTHFR deficiency. This deficiency results in hepatocyte degeneration, suggesting a 2

Lysine and novel hydroxylysine lipids in soil bacteria: amino acid membrane lipid response to temperature and pH in Pseudopedobacter saltans

PubMed Central

Moore, Eli K.; Hopmans, Ellen C.; Rijpstra, W. Irene C.; Sánchez-Andrea, Irene; Villanueva, Laura; Wienk, Hans; Schoutsen, Frans; Stams, Alfons J. M.; Sinninghe Damsté, Jaap S.

2015-01-01

Microbial decomposition of organic matter is an essential process in the global carbon cycle. The soil bacteria Pseudopedobacter saltans and Flavobacterium johnsoniae are both able to degrade complex organic molecules, but it is not fully known how their membrane structures are adapted to their environmental niche. The membrane lipids of these species were extracted and analyzed using high performance liquid chromatography-electrospray ionization/ion trap/mass spectrometry (HPLC-ESI/IT/MS) and high resolution accurate mass/mass spectrometry (HRAM/MS). Abundant unknown intact polar lipids (IPLs) from P. saltans were isolated and further characterized using amino acid analysis and two dimensional nuclear magnetic resonance (NMR) spectroscopy. Ornithine IPLs (OLs) with variable (hydroxy) fatty acid composition were observed in both bacterial species. Lysine-containing IPLs (LLs) were also detected in both species and were characterized here for the first time using HPLC-MS. Novel LLs containing hydroxy fatty acids and novel hydroxylysine lipids with variable (hydroxy) fatty acid composition were identified in P. saltans. The confirmation of OL and LL formation in F. johnsoniae and P. saltans and the presence of OlsF putative homologs in P. saltans suggest the OlsF gene coding protein is possibly involved in OL and LL biosynthesis in both species, however, potential pathways of OL and LL hydroxylation in P. saltans are still undetermined. Triplicate cultures of P. saltans were grown at three temperature/pH combinations: 30°C/pH 7, 15°C/pH 7, and 15°C/pH 9. The fractional abundance of total amino acid containing IPLs containing hydroxylated fatty acids was significantly higher at higher temperature, and the fractional abundance of lysine-containing IPLs was significantly higher at lower temperature and higher pH. These results suggest that these amino acid-containing IPLs, including the novel hydroxylysine lipids, could be involved in temperature and pH stress

Lipid sensing by mTOR complexes via de novo synthesis of phosphatidic acid.

PubMed

Menon, Deepak; Salloum, Darin; Bernfeld, Elyssa; Gorodetsky, Elizabeth; Akselrod, Alla; Frias, Maria A; Sudderth, Jessica; Chen, Pei-Hsuan; DeBerardinis, Ralph; Foster, David A

2017-04-14

mTOR, the mammalian target of rapamycin, integrates growth factor and nutrient signals to promote a transformation from catabolic to anabolic metabolism, cell growth, and cell cycle progression. Phosphatidic acid (PA) interacts with the FK506-binding protein-12-rapamycin-binding (FRB) domain of mTOR, which stabilizes both mTOR complexes: mTORC1 and mTORC2. We report here that mTORC1 and mTORC2 are activated in response to exogenously supplied fatty acids via the de novo synthesis of PA, a central metabolite for membrane phospholipid biosynthesis. We examined the impact of exogenously supplied fatty acids on mTOR in KRas-driven cancer cells, which are programmed to utilize exogenous lipids. The induction of mTOR by oleic acid was dependent upon the enzymes responsible for de novo synthesis of PA. Suppression of the de novo synthesis of PA resulted in G 1 cell cycle arrest. Although it has long been appreciated that mTOR is a sensor of amino acids and glucose, this study reveals that mTOR also senses the presence of lipids via production of PA. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Perilipin-related protein regulates lipid metabolism in C. elegans.

PubMed

Chughtai, Ahmed Ali; Kaššák, Filip; Kostrouchová, Markéta; Novotný, Jan Philipp; Krause, Michael W; Saudek, Vladimír; Kostrouch, Zdenek; Kostrouchová, Marta

2015-01-01

Perilipins are lipid droplet surface proteins that contribute to fat metabolism by controlling the access of lipids to lipolytic enzymes. Perilipins have been identified in organisms as diverse as metazoa, fungi, and amoebas but strikingly not in nematodes. Here we identify the protein encoded by the W01A8.1 gene in Caenorhabditis elegans as the closest homologue and likely orthologue of metazoan perilipin. We demonstrate that nematode W01A8.1 is a cytoplasmic protein residing on lipid droplets similarly as human perilipins 1 and 2. Downregulation or elimination of W01A8.1 affects the appearance of lipid droplets resulting in the formation of large lipid droplets localized around the dividing nucleus during the early zygotic divisions. Visualization of lipid containing structures by CARS microscopy in vivo showed that lipid-containing structures become gradually enlarged during oogenesis and relocate during the first zygotic division around the dividing nucleus. In mutant embryos, the lipid containing structures show defective intracellular distribution in subsequent embryonic divisions and become gradually smaller during further development. In contrast to embryos, lipid-containing structures in enterocytes and in epidermal cells of adult animals are smaller in mutants than in wild type animals. Our results demonstrate the existence of a perilipin-related regulation of fat metabolism in nematodes and provide new possibilities for functional studies of lipid metabolism.

Utilization of non-conventional systems for conversion of biomass to food components: Recovery optimization and characterizations of algal proteins and lipids

NASA Technical Reports Server (NTRS)

Karel, M.; Nakhost, Z.

1986-01-01

Protein isolate obtained from green algae (Scenedesmus obliquus) cultivated under controlled conditions was characterized. Molecular weight determination of fractionated algal proteins using SDS-polyacrylamide gel electrophoresis revealed a wide spectrum of molecular weights ranging from 15,000 to 220,000. Isoelectric points of dissociated proteins were in the range of 3.95 to 6.20. Amino acid composition of protein isolate compared favorably with FAO standards. High content of essential amino acids leucine, valine, phenylalanine and lysine makes algal protein isolate a high quality component of closed environment life support system (CELSS) diets. To optimize the removal of algal lipids and pigments supercritical carbon dioxide extraction (with and without ethanol as a co-solvent) was used. Addition of ethanol to supercritical CO2 resulted in more efficient removal of algal lipids and produced protein isolate with a good yield and protein recovery. The protein isolate extracted by the above mixture had an improved water solubility.

Reversible Nuclear-Lipid-Droplet Morphology Induced by Oleic Acid: A Link to Cellular-Lipid Metabolism

PubMed Central

Lagrutta, Lucía C.; Montero-Villegas, Sandra; Layerenza, Juan P.; Sisti, Martín S.; García de Bravo, Margarita M.

2017-01-01

Neutral lipids—involved in many cellular processes—are stored as lipid droplets (LD), those mainly cytosolic (cLD) along with a small nuclear population (nLD). nLD could be involved in nuclear-lipid homeostasis serving as an endonuclear buffering system that would provide or incorporate lipids and proteins involved in signalling pathways as transcription factors and as enzymes of lipid metabolism and nuclear processes. Our aim was to determine if nLD constituted a dynamic domain. Oleic-acid (OA) added to rat hepatocytes or HepG2 cells in culture produced cellular-phenotypic LD modifications: increases in TAG, CE, C, and PL content and in cLD and nLD numbers and sizes. LD increments were reversed on exclusion of OA and were prevented by inhibition of acyl-CoA synthetase (with Triacsin C) and thus lipid biosynthesis. Under all conditions, nLD corresponded to a small population (2–10%) of total cellular LD. The anabolism triggered by OA, involving morphologic and size changes within the cLD and nLD populations, was reversed by a net balance of catabolism, upon eliminating OA. These catabolic processes included lipolysis and the mobilization of hydrolyzed FA from the LD to cytosolic-oxidation sites. These results would imply that nLD are actively involved in nuclear processes that include lipids. In conclusion, nLD are a dynamic nuclear domain since they are modified by OA through a reversible mechanism in combination with cLD; this process involves acyl-CoA-synthetase activity; ongoing TAG, CE, and PL biosynthesis. Thus, liver nLD and cLD are both dynamic cellular organelles. PMID:28125673

The bovine seminal plasma protein PDC-109 extracts phosphorylcholine-containing lipids from the outer membrane leaflet.

PubMed

Tannert, Astrid; Kurz, Anke; Erlemann, Karl-Rudolf; Müller, Karin; Herrmann, Andreas; Schiller, Jürgen; Töpfer-Petersen, Edda; Manjunath, Puttaswamy; Müller, Peter

2007-04-01

The bovine seminal plasma protein PDC-109 modulates the maturation of bull sperm cells by removing lipids, mainly phosphatidylcholine and cholesterol, from their cellular membrane. Here, we have characterized the process of extraction of endogenous phospholipids and of their respective analogues. By measuring the PDC-109-mediated release of fluorescent phospholipid analogues from lipid vesicles and from biological membranes (human erythrocytes, bovine epididymal sperm cells), we showed that PDC-109 extracts phospholipids with a phosphorylcholine headgroup mainly from the outer leaflet of these membranes. The ability of PDC-109 to extract endogenous phospholipids from epididymal sperm cells was followed by mass spectrometry, which allowed us to characterize the fatty acid pattern of the released lipids. From these cells, PDC-109 extracted phosphatidylcholine and sphingomyelin that contained an enrichment of mono- and di-unsaturated fatty acids as well as short-chain and lyso-phosphatidylcholine species. Based on the results, a model explaining the phospholipid specificity of PDC-109-mediated lipid release is presented.

Jinlida granule inhibits palmitic acid induced-intracellular lipid accumulation and enhances autophagy in NIT-1 pancreatic β cells through AMPK activation.

PubMed

Wang, Dingkun; Tian, Min; Qi, Yuan; Chen, Guang; Xu, Lijun; Zou, Xin; Wang, Kaifu; Dong, Hui; Lu, Fuer

2015-02-23

Jinlida granule (JLDG), composed of seventeen Chinese medical herbs, is a widely used Chinese herbal prescription for treating diabetes mellitus. However, the mechanism underlying this effect remains unclear. To determine the main components in JLDG and to explore the effect of JLDG on autophagy and lipid accumulation in NIT-1 pancreatic β cells exposed to politic acid (PA) through AMP activated protein kinase (AMPK) signaling pathway. JLDG was prepared and the main components contained in the granules were identified by ultra performance liquid chromatography (UPLC) fingerprint. Intracellular lipid accumulation in NIT-1 cells was induced by culturing with medium containing PA. Intracellular lipid droplets were observed by Oil Red O staining and triglyceride (TG) content was measured by colorimetric assay. The formation of autophagosomes was observed under transmission electron microscope. The expression of AMPK and phospho-AMPK (pAMPK) proteins as well as its downstream fatty acid metabolism-related proteins (fatty acid synthase, FAS; acetyl-coA carboxylase, ACC; carnitine acyltransferase 1, CPT-1) and autophagy-related genes (mammal target of rapamycin, mTOR; tuberous sclerosis complex 1, TSC1; microtubule-associated protein 1 light chain 3, LC3-II) were determined by Western blot. The expression of sterol regulating element binding protein 1c (SREBP-1c) mRNA was examined by real time PCR (RT-PCR). Our data showed that JLDG could significantly reduce PA-induced intracellular lipid accumulation in NIT-1 pancreatic β cells. This effect was associated with increased protein expression of pAMPK and AMPK in NIT-1 cells. Treatment with JLDG also decreased the expression of AMPK downstream lipogenic genes (SREBP-1c mRNA, FAS and ACC proteins) whereas increased the expression of fatty acid oxidation gene (CPT-1 protein). Additionally, JLDG-treated cells displayed a markedly increase in the number of autophagosomes which was accompanied by the down-regulation of m

Mechanisms of Lipid Accumulation in the Bone Morphogenetic Protein Receptor Type 2 Mutant Right Ventricle

PubMed Central

Brittain, Evan L.; Fessel, Joshua P.; Penner, Niki; Atkinson, James; Funke, Mitch; Grueter, Carrie; Jerome, W. Gray; Freeman, Michael; Newman, John H.; West, James; Hemnes, Anna R.

2016-01-01

Rationale: In heritable pulmonary arterial hypertension with germline mutation in the bone morphogenetic protein receptor type 2 (BMPR2) gene, right ventricle (RV) dysfunction is associated with RV lipotoxicity; however, the underlying mechanism for lipid accumulation is not known. Objectives: We hypothesized that lipid accumulation in cardiomyocytes with BMPR2 mutation occurs owing to alterations in lipid transport and impaired fatty acid oxidation (FAO), which is exacerbated by a high-lipid (Western) diet (WD). Methods: We used a transgenic mouse model of pulmonary arterial hypertension with mutant BMPR2 and generated a cardiomyocyte cell line with BMPR2 mutation. Electron microscopy and metabolomic analysis were performed on mouse RVs. Measurements and Main Results: By metabolomics analysis, we found an increase in long-chain fatty acids in BMPR2 mutant mouse RVs compared with controls, which correlated with cardiac index. BMPR2-mutant cardiomyocytes had increased lipid compared with controls. Direct measurement of FAO in the WD-fed BMPR2-mutant RV showed impaired palmitate-linked oxygen consumption, and metabolomics analysis showed reduced indices of FAO. Using both mutant BMPR2 mouse RVs and cardiomyocytes, we found an increase in the uptake of 14C-palmitate and fatty acid transporter CD36 that was further exacerbated by WD. Conclusions: Taken together, our data suggest that impaired FAO and increased expression of the lipid transporter CD36 are key mechanisms underlying lipid deposition in the BMPR2-mutant RV, which are exacerbated in the presence of dietary lipids. These findings suggest important features leading to RV lipotoxicity in pulmonary arterial hypertension and may point to novel areas of therapeutic intervention. PMID:27077479

Anaerobic digestion of cattle offal: protein and lipid-rich substrate degradation and population dynamics of acidogens and methanogens.

PubMed

Lee, Joonyeob; Koo, Taewoan; Han, Gyuseong; Shin, Seung Gu; Hwang, Seokhwan

2015-12-01

Anaerobic digestion of cattle offal was investigated in batch reactors at 35 °C to determine the feasibility of using cattle offal as a feedstock. The organic content [i.e., volatile solids (VS)] of the cattle offal was mainly composed of protein (33.9%) and lipids (46.1%). Hydrolysis along with acidogenesis was monitored to investigate the substrate degradation and generation of intermediate products (e.g., volatile fatty acids, ammonia). Acetate (2.03 g/L), propionate (0.60 g/L), n-butyrate (0.39 g/L), and iso-valerate (0.37 g/L) were major acidogenesis products (91% of total volatile fatty acid concentration). Overall protein and lipid degradation were 82.9 and 81.8%, respectively. Protein degraded first, and four times faster (0.28 day(-1)) than lipid (0.07 day(-1)). Methane yields were 0.52 L CH4/g VSadded and 0.65 L CH4/g VSremoved, indicating that anaerobic digestion of the offal was feasible. A quantitative QPCR assay was conducted to understand the microbial dynamics. The variation patt erns in the gene concentrations successfully indicated the population dynamics of proteolytic and lipolytic acidogens. A fourth-order Runge-Kutta approximation was used to determine the kinetics of the acidogens. The molecular biotechnology approach was appropriate for the evaluation of the acidogenic biokinetics. The maximum growth rate, μ m, halfsaturation coefficients, K s, microbial yield coefficient, Y, cell mass decay rate coefficient, k d, of the proteolytic acidogens were 9.9 day(-1), 37.8 g protein/L, 1.1 × 10(10) copies/g protein, and 3.8 × 10(-1), respectively. Those for the lipolytic acidogens were 1.2 × 10(-1) day(-1), 8.3 g lipid/L, 1.5 × 10(9) copies/g lipid, and 9.9 × 10(-3) day(-1), respectively.

Domain Formation Induced by the Adsorption of Charged Proteins on Mixed Lipid Membranes

PubMed Central

Mbamala, Emmanuel C.; Ben-Shaul, Avinoam; May, Sylvio

2005-01-01

Peripheral proteins can trigger the formation of domains in mixed fluid-like lipid membranes. We analyze the mechanism underlying this process for proteins that bind electrostatically onto a flat two-component membrane, composed of charged and neutral lipid species. Of particular interest are membranes in which the hydrocarbon lipid tails tend to segregate owing to nonideal chain mixing, but the (protein-free) lipid membrane is nevertheless stable due to the electrostatic repulsion between the charged lipid headgroups. The adsorption of charged, say basic, proteins onto a membrane containing anionic lipids induces local lipid demixing, whereby charged lipids migrate toward (or away from) the adsorption site, so as to minimize the electrostatic binding free energy. Apart from reducing lipid headgroup repulsion, this process creates a gradient in lipid composition around the adsorption zone, and hence a line energy whose magnitude depends on the protein's size and charge and the extent of lipid chain nonideality. Above a certain critical lipid nonideality, the line energy is large enough to induce domain formation, i.e., protein aggregation and, concomitantly, macroscopic lipid phase separation. We quantitatively analyze the thermodynamic stability of the dressed membrane based on nonlinear Poisson-Boltzmann theory, accounting for both the microscopic characteristics of the proteins and lipid composition modulations at and around the adsorption zone. Spinodal surfaces and critical points of the dressed membranes are calculated for several different model proteins of spherical and disk-like shapes. Among the models studied we find the most substantial protein-induced membrane destabilization for disk-like proteins whose charges are concentrated in the membrane-facing surface. If additional charges reside on the side faces of the proteins, direct protein-protein repulsion diminishes considerably the propensity for domain formation. Generally, a highly charged flat face

Lipid nanotechnologies for structural studies of membrane-associated proteins.

PubMed

Stoilova-McPhie, Svetla; Grushin, Kirill; Dalm, Daniela; Miller, Jaimy

2014-11-01

We present a methodology of lipid nanotubes (LNT) and nanodisks technologies optimized in our laboratory for structural studies of membrane-associated proteins at close to physiological conditions. The application of these lipid nanotechnologies for structure determination by cryo-electron microscopy (cryo-EM) is fundamental for understanding and modulating their function. The LNTs in our studies are single bilayer galactosylceramide based nanotubes of ∼20 nm inner diameter and a few microns in length, that self-assemble in aqueous solutions. The lipid nanodisks (NDs) are self-assembled discoid lipid bilayers of ∼10 nm diameter, which are stabilized in aqueous solutions by a belt of amphipathic helical scaffold proteins. By combining LNT and ND technologies, we can examine structurally how the membrane curvature and lipid composition modulates the function of the membrane-associated proteins. As proof of principle, we have engineered these lipid nanotechnologies to mimic the activated platelet's phosphtaidylserine rich membrane and have successfully assembled functional membrane-bound coagulation factor VIII in vitro for structure determination by cryo-EM. The macromolecular organization of the proteins bound to ND and LNT are further defined by fitting the known atomic structures within the calculated three-dimensional maps. The combination of LNT and ND technologies offers a means to control the design and assembly of a wide range of functional membrane-associated proteins and complexes for structural studies by cryo-EM. The presented results confirm the suitability of the developed methodology for studying the functional structure of membrane-associated proteins, such as the coagulation factors, at a close to physiological environment. © 2014 Wiley Periodicals, Inc.

Protein Analysis of Sapienic Acid-Treated Porphyromonas gingivalis Suggests Differential Regulation of Multiple Metabolic Pathways.

PubMed

Fischer, Carol L; Dawson, Deborah V; Blanchette, Derek R; Drake, David R; Wertz, Philip W; Brogden, Kim A

2016-01-01

Lipids endogenous to skin and mucosal surfaces exhibit potent antimicrobial activity against Porphyromonas gingivalis, an important colonizer of the oral cavity implicated in periodontitis. Our previous work demonstrated the antimicrobial activity of the fatty acid sapienic acid (C(16:1Δ6)) against P. gingivalis and found that sapienic acid treatment alters both protein and lipid composition from those in controls. In this study, we further examined whole-cell protein differences between sapienic acid-treated bacteria and untreated controls, and we utilized open-source functional association and annotation programs to explore potential mechanisms for the antimicrobial activity of sapienic acid. Our analyses indicated that sapienic acid treatment induces a unique stress response in P. gingivalis resulting in differential expression of proteins involved in a variety of metabolic pathways. This network of differentially regulated proteins was enriched in protein-protein interactions (P = 2.98 × 10(-8)), including six KEGG pathways (P value ranges, 2.30 × 10(-5) to 0.05) and four Gene Ontology (GO) molecular functions (P value ranges, 0.02 to 0.04), with multiple suggestive enriched relationships in KEGG pathways and GO molecular functions. Upregulated metabolic pathways suggest increases in energy production, lipid metabolism, iron acquisition and processing, and respiration. Combined with a suggested preferential metabolism of serine, which is necessary for fatty acid biosynthesis, these data support our previous findings that the site of sapienic acid antimicrobial activity is likely at the bacterial membrane. P. gingivalis is an important opportunistic pathogen implicated in periodontitis. Affecting nearly 50% of the population, periodontitis is treatable, but the resulting damage is irreversible and eventually progresses to tooth loss. There is a great need for natural products that can be used to treat and/or prevent the overgrowth of periodontal pathogens and

Calcium Ions as “Miscibility Switch”: Colocalization of Surfactant Protein B with Anionic Lipids under Absolute Calcium Free Conditions

PubMed Central

Saleem, Mohammed; Meyer, Michaela C.; Breitenstein, Daniel; Galla, Hans-Joachim

2009-01-01

Abstract One of the main determinants of lung surfactant function is the complex interplay between its protein and lipid components. The lipid specificity of surfactant protein B (SP-B), however, and the protein's ability to selectively squeeze out lipids, has remained contradictory. In this work we present, for the first time to our knowledge, by means of time-of-flight secondary ion mass spectrometry chemical imaging, a direct evidence for colocalization of SP-B as well as its model peptide KL4 with negatively charged dipalmitoylphosphatidylglycerol under absolute calcium free conditions. Our results prove that protein/lipid localization depends on the miscibility of all surfactant components, which itself is influenced by subphase ionic conditions. In contrast to our earlier studies reporting SP-B/KL4 colocalization with zwitterionic dipalmitoylphosphatidylcholine, in the presence of even the smallest traces of calcium, we finally evidence an apparent reversal of protein/lipid mixing behavior upon calcium removal with ethylene diamine tetraacetic acid. In addition, scanning force microscopy measurements reveal that by depleting the subphase from calcium ions the protrusion formation ability of SP-B or KL4 is not hampered. However, in the case of KL4, distinct differences in protrusion morphology and height are visible. Our results support the idea that calcium ions act as a “miscibility switch” in surfactant model systems and probably are one of the major factors steering lipid/protein mixing behavior as well as influencing the protein's protrusion formation ability. PMID:19619464

Short-Chain Fatty Acids Enhance the Lipid Accumulation of 3T3-L1 Cells by Modulating the Expression of Enzymes of Fatty Acid Metabolism.

PubMed

Yu, Haining; Li, Ran; Huang, Haiyong; Yao, Ru; Shen, Shengrong

2018-01-01

Short-chain fatty acids (SCFA) such as acetic acid, propionic acid, and butyric acid are produced by fermentation by gut microbiota. In this paper, we investigate the effects of SCFA on 3T3-L1 cells and the underlying molecular mechanisms. The cells were treated with acetic acid, propionic acid, or butyric acid when cells were induced to differentiate into adipocytes. MTT assay was employed to detect the viability of 3T3-L1 cells. Oil Red O staining was used to visualize the lipid content in 3T3-L1 cells. A triglyceride assay kit was used to detect the triacylglycerol content in 3T3-L1 cells. qRT-PCR and Western blot were used to evaluate the expression of metabolic enzymes. MTT results showed that safe concentrations of acetic acid, propionic acid, and butyric acid were less than 6.4, 3.2, and 0.8 mM, respectively. Oil Red O staining and triacylglycerols detection results showed that treatment with acetic acid, propionic acid, and butyric acid accelerated the 3T3-L1 adipocyte differentiation. qRT-PCR and Western blot results showed that the expressions of lipoprotein lipase (LPL), adipocyte fatty acid binding protein 4 (FABP4), fatty acid transporter protein 4 (FATP4), and fatty acid synthase (FAS) were significantly increased by acetic acid, propionic acid, and butyric acid treatment during adipose differentiation (p < 0.05). In conclusion, SCFA promoted lipid accumulation by modulating the expression of enzymes of fatty acid metabolism. © 2018 AOCS.

An assembly of proteins and lipid domains regulates transport of phosphatidylserine to phosphatidylserine decarboxylase 2 in Saccharomyces cerevisiae.

PubMed

Riekhof, Wayne R; Wu, Wen-I; Jones, Jennifer L; Nikrad, Mrinalini; Chan, Mallory M; Loewen, Christopher J R; Voelker, Dennis R

2014-02-28

Saccharomyces cerevisiae uses multiple biosynthetic pathways for the synthesis of phosphatidylethanolamine. One route involves the synthesis of phosphatidylserine (PtdSer) in the endoplasmic reticulum (ER), the transport of this lipid to endosomes, and decarboxylation by PtdSer decarboxylase 2 (Psd2p) to produce phosphatidylethanolamine. Several proteins and protein motifs are known to be required for PtdSer transport to occur, namely the Sec14p homolog PstB2p/Pdr17p; a PtdIns 4-kinase, Stt4p; and a C2 domain of Psd2p. The focus of this work is on defining the protein-protein and protein-lipid interactions of these components. PstB2p interacts with a protein encoded by the uncharacterized gene YPL272C, which we name Pbi1p (PstB2p-interacting 1). PstB2p, Psd2, and Pbi1p were shown to be lipid-binding proteins specific for phosphatidic acid. Pbi1p also interacts with the ER-localized Scs2p, a binding determinant for several peripheral ER proteins. A complex between Psd2p and PstB2p was also detected, and this interaction was facilitated by a cryptic C2 domain at the extreme N terminus of Psd2p (C2-1) as well the previously characterized C2 domain of Psd2p (C2-2). The predicted N-terminal helical region of PstB2p was necessary and sufficient for promoting the interaction with both Psd2p and Pbi1p. Taken together, these results support a model for PtdSer transport involving the docking of a PtdSer donor membrane with an acceptor via specific protein-protein and protein-lipid interactions. Specifically, our model predicts that this process involves an acceptor membrane complex containing the C2 domains of Psd2p, PstB2p, and Pbi1p that ligate to Scs2p and phosphatidic acid present in the donor membrane, forming a zone of apposition that facilitates PtdSer transfer.

NMR studies reveal the role of biomembranes in modulating ligand binding and release by intracellular bile acid binding proteins.

PubMed

Pedò, Massimo; Löhr, Frank; D'Onofrio, Mariapina; Assfalg, Michael; Dötsch, Volker; Molinari, Henriette

2009-12-18

Bile acid molecules are transferred vectorially between basolateral and apical membranes of hepatocytes and enterocytes in the context of the enterohepatic circulation, a process regulating whole body lipid homeostasis. This work addresses the role of the cytosolic lipid binding proteins in the intracellular transfer of bile acids between different membrane compartments. We present nuclear magnetic resonance (NMR) data describing the ternary system composed of the bile acid binding protein, bile acids, and membrane mimetic systems, such as anionic liposomes. This work provides evidence that the investigated liver bile acid binding protein undergoes association with the anionic membrane and binding-induced partial unfolding. The addition of the physiological ligand to the protein-liposome mixture is capable of modulating this interaction, shifting the equilibrium towards the free folded holo protein. An ensemble of NMR titration experiments, based on nitrogen-15 protein and ligand observation, confirm that the membrane and the ligand establish competing binding equilibria, modulating the cytoplasmic permeability of bile acids. These results support a mechanism of ligand binding and release controlled by the onset of a bile salt concentration gradient within the polarized cell. The location of a specific protein region interacting with liposomes is highlighted.

Liver X receptors balance lipid stores in hepatic stellate cells through Rab18, a retinoid responsive lipid droplet protein.

PubMed

O'Mahony, Fiona; Wroblewski, Kevin; O'Byrne, Sheila M; Jiang, Hongfeng; Clerkin, Kara; Benhammou, Jihane; Blaner, William S; Beaven, Simon W

2015-08-01

Liver X receptors (LXRs) are determinants of hepatic stellate cell (HSC) activation and liver fibrosis. Freshly isolated HSCs from Lxrαβ(-/-) mice have increased lipid droplet (LD) size, but the functional consequences of this are unknown. Our aim was to determine whether LXRs link cholesterol to retinoid storage in HSCs and how this impacts activation. Primary HSCs from Lxrαβ(-/-) and wild-type mice were profiled by gene array during in vitro activation. Lipid content was quantified by high-performance liquid chromatography and mass spectroscopy. Primary HSCs were treated with nuclear receptor ligands, transfected with small interfering RNA and plasmid constructs, and analyzed by immunocytochemistry. Lxrαβ(-/-) HSCs have increased cholesterol and retinyl esters. The retinoid increase drives intrinsic retinoic acid receptor signaling, and activation occurs more rapidly in Lxrαβ(-/-) HSCs. We identify Rab18 as a novel retinoic acid-responsive, LD-associated protein that helps mediate stellate cell activation. Rab18 mRNA, protein, and membrane insertion increase during activation. Both Rab18 guanosine triphosphatase activity and isoprenylation are required for stellate cell LD loss and induction of activation markers. These phenomena are accelerated in Lxrαβ(-/-) HSCs, where there is greater retinoic acid flux. Conversely, Rab18 knockdown retards LD loss in culture and blocks activation, just like the functional mutants. Rab18 is also induced with acute liver injury in vivo. Retinoid and cholesterol metabolism are linked in stellate cells by the LD-associated protein Rab18. Retinoid overload helps explain the profibrotic phenotype of Lxrαβ(-/-) mice, and we establish a pivotal role for Rab18 GTPase activity and membrane insertion in wild-type stellate cell activation. Interference with Rab18 may have significant therapeutic benefit in ameliorating liver fibrosis. © 2015 by the American Association for the Study of Liver Diseases.

Activation of AMPK by berberine induces hepatic lipid accumulation by upregulation of fatty acid translocase CD36 in mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, You-Jin; Lee, Kang-Yo; Jung, Seung-Hwan

Emerging evidence has shown that berberine has a protective effect against metabolic syndrome such as obesity and type II diabetes mellitus by activating AMP-activated protein kinase (AMPK). AMPK induces CD36 trafficking to the sarcolemma for fatty acid uptake and oxidation in contracting muscle. However, little is known about the effects of AMPK on CD36 regulation in the liver. We investigated whether AMPK activation by berberine affects CD36 expression and fatty acid uptake in hepatocytes and whether it is linked to hepatic lipid accumulation. Activation of AMPK by berberine or transduction with adenoviral vectors encoding constitutively active AMPK in HepG2 andmore » mouse primary hepatocytes increased the expression and membrane translocation of CD36, resulting in enhanced fatty acid uptake and lipid accumulation as determined by BODIPY-C16 and Nile red fluorescence, respectively. Activation of AMPK by berberine induced the phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2) and subsequently induced CCAAT/enhancer-binding protein β (C/EBPβ) binding to the C/EBP-response element in the CD36 promoter in hepatocytes. In addition, hepatic CD36 expression and triglyceride levels were increased in normal diet-fed mice treated with berberine, but completely prevented when hepatic CD36 was silenced with adenovirus containing CD36-specific shRNA. Taken together, prolonged activation of AMPK by berberine increased CD36 expression in hepatocytes, resulting in fatty acid uptake via processes linked to hepatocellular lipid accumulation and fatty liver. - Highlights: • Berberine increases the expression and membrane translocation of CD36 in hepatocytes. • The increase of CD36 results in enhanced fatty acid uptake and lipid accumulation. • Berberine-induced fatty liver is mediated by AMPK-ERK-C/EBPβ pathway. • CD36-specific shRNA inhibited berberine-induced lipid accumulation in liver.« less

Regulation of Lipid and Glucose Metabolism by Phosphatidylcholine Transfer Protein

PubMed Central

Kang, Hye Won; Wei, Jie; Cohen, David E.

2010-01-01

Phosphatidylcholine transfer protein (PC-TP, a.k.a. StARD2) binds phosphatidylcholines and catalyzes their intermembrane transfer and exchange in vitro. The structure of PC-TP comprises a hydrophobic pocket and a well-defined head-group binding site, and its gene expression is regulated by peroxisome proliferator activated receptor α. Recent studies have revealed key regulatory roles for PC-TP in lipid and glucose metabolism. Notably, Pctp−/− mice are sensitized to insulin action and exhibit more efficient brown fat-mediated thermogenesis. PC-TP appears to limit access of fatty acids to mitochondria by stimulating the activity of thioesterase superfamily member 2, a newly characterized long-chain fatty acyl-CoA thioesterase. Because PC-TP discriminates among phosphatidylcholines within lipid bilayers, it may function as a sensor that links metabolic regulation to membrane composition. PMID:20338778

Keap1-knockdown decreases fasting-induced fatty liver via altered lipid metabolism and decreased fatty acid mobilization from adipose tissue.

PubMed

Xu, Jialin; Donepudi, Ajay C; Moscovitz, Jamie E; Slitt, Angela L

2013-01-01

The purpose of this study was to determine whether Nrf2 activation, via Keap1-knockdown (Keap1-KD), regulates lipid metabolism and mobilization induced by food deprivation (e.g. fasting). Male C57BL/6 (WT) and Keap1-KD mice were either fed ad libitum or food deprived for 24 hours. After fasting, WT mice exhibited a marked increase in hepatic lipid accumulation, but Keap1-KD mice had an attenuated increase of lipid accumulation, along with reduced expression of lipogenic genes (acetyl-coA carboxylase, stearoyl-CoA desaturase-1, and fatty acid synthase) and reduced expression of genes related to fatty acid transport, such as fatty acid translocase/CD36 (CD36) and Fatty acid transport protein (FATP) 2, which may attribute to the reduced induction of Peroxisome proliferator-activated receptor (Ppar) α signaling in the liver. Additionally, enhanced Nrf2 activity by Keap1-KD increased AMP-activated protein kinase (AMPK) phosphorylation in liver. In white adipose tissue, enhanced Nrf2 activity did not change the lipolysis rate by fasting, but reduced expression of fatty acid transporters--CD36 and FATP1, via a PPARα-dependent mechanism, which impaired fatty acid transport from white adipose tissue to periphery circulation system, and resulted in increased white adipose tissue fatty acid content. Moreover, enhanced Nrf2 activity increased glucose tolerance and Akt phosphorylation levels upon insulin administration, suggesting Nrf2 signaling pathway plays a key role in regulating insulin signaling and enhanced insulin sensitivity in skeletal muscle. Enhanced Nrf2 activity via Keap1-KD decreased fasting-induced steatosis, pointing to an important function of Nrf2 on lipid metabolism under the condition of nutrient deprivation.

Monoolein Lipid Phases as Incorporation and Enrichment Materials for Membrane Protein Crystallization

PubMed Central

Wallace, Ellen; Dranow, David; Laible, Philip D.; Christensen, Jeff; Nollert, Peter

2011-01-01

The crystallization of membrane proteins in amphiphile-rich materials such as lipidic cubic phases is an established methodology in many structural biology laboratories. The standard procedure employed with this methodology requires the generation of a highly viscous lipidic material by mixing lipid, for instance monoolein, with a solution of the detergent solubilized membrane protein. This preparation is often carried out with specialized mixing tools that allow handling of the highly viscous materials while minimizing dead volume to save precious membrane protein sample. The processes that occur during the initial mixing of the lipid with the membrane protein are not well understood. Here we show that the formation of the lipidic phases and the incorporation of the membrane protein into such materials can be separated experimentally. Specifically, we have investigated the effect of different initial monoolein-based lipid phase states on the crystallization behavior of the colored photosynthetic reaction center from Rhodobacter sphaeroides. We find that the detergent solubilized photosynthetic reaction center spontaneously inserts into and concentrates in the lipid matrix without any mixing, and that the initial lipid material phase state is irrelevant for productive crystallization. A substantial in-situ enrichment of the membrane protein to concentration levels that are otherwise unobtainable occurs in a thin layer on the surface of the lipidic material. These results have important practical applications and hence we suggest a simplified protocol for membrane protein crystallization within amphiphile rich materials, eliminating any specialized mixing tools to prepare crystallization experiments within lipidic cubic phases. Furthermore, by virtue of sampling a membrane protein concentration gradient within a single crystallization experiment, this crystallization technique is more robust and increases the efficiency of identifying productive crystallization

Naphthylacetic Acid and Tea Polyphenol Application Promote Biomass and Lipid Production of Nervonic Acid-Producing Microalgae.

PubMed

Xu, Feng; Fan, Yong; Miao, Fuhong; Hu, Guang-Rong; Sun, Juan; Yang, Guofeng; Li, Fu-Li

2018-01-01

Mychonastes afer HSO-3-1 is a potential producer of nervonic acid, which could be accumulated to 2-3% of dry cell weight. Improving the productivity of nervonic acid is critical to promote the commercialization of this product. In this study, 1-naphthylacetic acid (NAA) and tea polyphenol (TP) were selected as bioactive additives to stimulate the growth of M. afer . Supplementing NAA in the early growth stage and TP in the middle and late growth stage led to improved lipid accumulation in M. afer . The cultures supplemented with TP at the late growth stage maintained higher photosynthetic efficiency than the control groups without TP. Furthermore, the intracellular reactive oxygen species (ROS) accumulations in M. afer supplemented with 500 mg/L of TP was 63% lower than the control group. A linear relationship ( R 2 = 0.899) between the values of Fv/Fm and ROS accumulation was established. We hypothesize supplement of bioactive additives at different growth stage could promote the cell growth rate and nervonic acid productivity of M. afer by retrieving intracellular ROS level. Further analysis of photosynthetic system II (PSII) protein in M. afer cultured in presence of NAA and TP indicated the levels of D1 and D2 proteins, the core skeleton proteins of PSII, showed 33.3 and 25.6% higher than the control group. CP43 protein, a critical module in PSII repair cycle, decreased significantly. These implied that TP possesses the function of slowing down the damage of PSII by scavenging excess intracellular ROS.

Vaccinia Virus Immunomodulator A46: A Lipid and Protein-Binding Scaffold for Sequestering Host TIR-Domain Proteins

PubMed Central

Radakovics, Katharina; Smith, Terry K.; Bobik, Nina; Round, Adam; Djinović-Carugo, Kristina; Usón, Isabel

2016-01-01

Vaccinia virus interferes with early events of the activation pathway of the transcriptional factor NF-kB by binding to numerous host TIR-domain containing adaptor proteins. We have previously determined the X-ray structure of the A46 C-terminal domain; however, the structure and function of the A46 N-terminal domain and its relationship to the C-terminal domain have remained unclear. Here, we biophysically characterize residues 1–83 of the N-terminal domain of A46 and present the X-ray structure at 1.55 Å. Crystallographic phases were obtained by a recently developed ab initio method entitled ARCIMBOLDO_BORGES that employs tertiary structure libraries extracted from the Protein Data Bank; data analysis revealed an all β-sheet structure. This is the first such structure solved by this method which should be applicable to any protein composed entirely of β-sheets. The A46(1–83) structure itself is a β-sandwich containing a co-purified molecule of myristic acid inside a hydrophobic pocket and represents a previously unknown lipid-binding fold. Mass spectrometry analysis confirmed the presence of long-chain fatty acids in both N-terminal and full-length A46; mutation of the hydrophobic pocket reduced the lipid content. Using a combination of high resolution X-ray structures of the N- and C-terminal domains and SAXS analysis of full-length protein A46(1–240), we present here a structural model of A46 in a tetrameric assembly. Integrating affinity measurements and structural data, we propose how A46 simultaneously interferes with several TIR-domain containing proteins to inhibit NF-κB activation and postulate that A46 employs a bipartite binding arrangement to sequester the host immune adaptors TRAM and MyD88. PMID:27973613

Performance of structured lipids incorporating selected phenolic and ascorbic acids.

PubMed

Gruczynska, Eliza; Przybylski, Roman; Aladedunye, Felix

2015-04-15

Conditions applied during frying require antioxidant which is stable at these conditions and provides protection for frying oil and fried food. Novel structured lipids containing nutraceuticals and antioxidants were formed by enzymatic transesterification, exploring canola oil and naturally occurring antioxidants such as ascorbic and selected phenolic acids as substrates. Lipozyme RM IM lipase from Rhizomucor miehei was used as biocatalyst. Frying performance and oxidative stability of the final transesterification products were evaluated. The novel lipids showed significantly improved frying performance compared to canola oil. Oxidative stability assessment of the structured lipids showed significant improvement in resistance to oxidative deterioration compared to original canola oil. Interestingly, the presence of ascorbic acid in an acylglycerol structure protected α-tocopherol against thermal degradation, which was not observed for the phenolic acids. Developed structured lipids containing nutraceuticals and antioxidants may directly affect nutritional properties of lipids also offering nutraceutical ingredients for food formulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

GRIFFIN: A versatile methodology for optimization of protein-lipid interfaces for membrane protein simulations

PubMed Central

Staritzbichler, René; Anselmi, Claudio; Forrest, Lucy R.; Faraldo-Gómez, José D.

2014-01-01

As new atomic structures of membrane proteins are resolved, they reveal increasingly complex transmembrane topologies, and highly irregular surfaces with crevices and pores. In many cases, specific interactions formed with the lipid membrane are functionally crucial, as is the overall lipid composition. Compounded with increasing protein size, these characteristics pose a challenge for the construction of simulation models of membrane proteins in lipid environments; clearly, that these models are sufficiently realistic bears upon the reliability of simulation-based studies of these systems. Here, we introduce GRIFFIN, which uses a versatile framework to automate and improve a widely-used membrane-embedding protocol. Initially, GRIFFIN carves out lipid and water molecules from a volume equivalent to that of the protein, so as to conserve the system density. In the subsequent optimization phase GRIFFIN adds an implicit grid-based protein force-field to a molecular dynamics simulation of the pre-carved membrane. In this force-field, atoms inside the implicit protein volume experience an outward force that will expel them from that volume, whereas those outside are subject to electrostatic and van-der-Waals interactions with the implicit protein. At each step of the simulation, these forces are updated by GRIFFIN and combined with the intermolecular forces of the explicit lipid-water system. This procedure enables the construction of realistic and reproducible starting configurations of the protein-membrane interface within a reasonable timeframe and with minimal intervention. GRIFFIN is a standalone tool designed to work alongside any existing molecular dynamics package, such as NAMD or GROMACS. PMID:24707227

Effect of endogenous proteins and lipids on starch digestibility in rice flour.

PubMed

Ye, Jiangping; Hu, Xiuting; Luo, Shunjing; McClements, David Julian; Liang, Lu; Liu, Chengmei

2018-04-01

The composition and structure of the food matrix can have a major impact on the digestion. The aim of this work was to investigate the effects of endogenous proteins and lipids on starch digestibility in rice flour, with an emphasis on establishing the underlying physicochemical mechanisms involved. Native long-grain indica rice flour and rice flour with the lipids and/or proteins removed were subjected to a simulated digestion in vitro. A significant increase in starch digestibility was observed after removal of proteins, lipids, or both. The starch digestibility of the rice flour without lipids was slightly lower than that without proteins, even though the proteins content was about 10-fold higher than the lipids content. Microstructural analysis suggested that the proteins and lipids were normally attached to the surfaces of the starch granules in the native rice flour, thus inhibiting their contact with digestive enzymes. Moreover, the proteins and lipids restricted the swelling of the starch granules, which may have decreased their digestion by reducing their surface areas. In addition, amylose-lipid complex was detected in the rice flour, which is also known to slow down starch digestion. These results have important implications for the design of foods with improved nutritional profiles. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Luciferase-fragment Complementation Assay to Detect Lipid Droplet-associated Protein-Protein Interactions*

PubMed Central

Kolkhof, Petra; Werthebach, Michael; van de Venn, Anna; Poschmann, Gereon; Chen, Lili; Welte, Michael; Stühler, Kai; Beller, Mathias

2017-01-01

A critical challenge for all organisms is to carefully control the amount of lipids they store. An important node for this regulation is the protein coat present at the surface of lipid droplets (LDs), the intracellular organelles dedicated to lipid storage. Only limited aspects of this regulation are understood so far. For the probably best characterized case, the regulation of lipolysis in mammals, some of the major protein players have been identified, and it has been established that this process crucially depends on an orchestrated set of protein-protein interactions. Proteomic analysis has revealed that LDs are associated with dozens, if not hundreds, of different proteins, most of them poorly characterized, with even fewer data regarding which of them might physically interact. To comprehensively understand the mechanism of lipid storage regulation, it will likely be essential to define the interactome of LD-associated proteins. Previous studies of such interactions were hampered by technical limitations. Therefore, we have developed a split-luciferase based protein-protein interaction assay and test for interactions among 47 proteins from Drosophila and from mouse. We confirmed previously described interactions and identified many new ones. In 1561 complementation tests, we assayed for interactions among 487 protein pairs of which 92 (19%) resulted in a successful luciferase complementation. These results suggest that a prominent fraction of the LD-associated proteome participates in protein-protein interactions. In targeted experiments, we analyzed the two proteins Jabba and CG9186 in greater detail. Jabba mediates the sequestration of histones to LDs. We successfully applied our split luciferase complementation assay to learn more about this function as we were e.g. able to map the interaction between Jabba and histones. For CG9186, expression levels affect the positioning of LDs. Here, we reveal the ubiquitination of CG9186, and link this

Probing protein-lipid interactions by FRET between membrane fluorophores

NASA Astrophysics Data System (ADS)

Trusova, Valeriya M.; Gorbenko, Galyna P.; Deligeorgiev, Todor; Gadjev, Nikolai

2016-09-01

Förster resonance energy transfer (FRET) is a powerful fluorescence technique that has found numerous applications in medicine and biology. One area where FRET proved to be especially informative involves the intermolecular interactions in biological membranes. The present study was focused on developing and verifying a Monte-Carlo approach to analyzing the results of FRET between the membrane-bound fluorophores. This approach was employed to quantify FRET from benzanthrone dye ABM to squaraine dye SQ-1 in the model protein-lipid system containing a polycationic globular protein lysozyme and negatively charged lipid vesicles composed of phosphatidylcholine and phosphatidylglycerol. It was found that acceptor redistribution between the lipid bilayer and protein binding sites resulted in the decrease of FRET efficiency. Quantification of this effect in terms of the proposed methodology yielded both structural and binding parameters of lysozyme-lipid complexes.

Cationic amino acid based lipids as effective nonviral gene delivery vectors for primary cultured neurons.

PubMed

Aoshima, Yumiko; Hokama, Ryosuke; Sou, Keitaro; Sarker, Satya Ranjan; Iida, Kabuto; Nakamura, Hideki; Inoue, Takafumi; Takeoka, Shinji

2013-12-18

The delivery of specific genes into neurons offers a potent approach for treatment of diseases as well as for the study of neuronal cell biology. Here we investigated the capabilities of cationic amino acid based lipid assemblies to act as nonviral gene delivery vectors in primary cultured neurons. An arginine-based lipid, Arg-C3-Glu2C14, and a lysine-based lipid, Lys-C3-Glu2C14, with two different types of counterion, chloride ion (Cl-) and trifluoroacetic acid (TFA-), were shown to successfully mediate transfection of primary cultured neurons with plasmid DNA encoding green fluorescent protein. Among four types of lipids, we optimized their conditions such as the lipid-to-DNA ratio and the amount of pDNA and conducted a cytotoxicity assay at the same time. Overall, Arg-C3-Glu2C14 with TFA- induced a rate of transfection in primary cultured neurons higher than that of Lys-C3-Glu2C14 using an optimal weight ratio of lipid-to-plasmid DNA of 1. Moreover, it was suggested that Arg-C3-Glu2C14 with TFA- showed the optimized value higher than that of Lipofectamine2000 in experimental conditions. Thus, Arg-C3-Glu2C14 with TFA- is a promising candidate as a reliable transfection reagent for primary cultured neurons with a relatively low cytotoxicity.

Cationic Amino Acid Based Lipids as Effective Nonviral Gene Delivery Vectors for Primary Cultured Neurons

PubMed Central

2013-01-01

The delivery of specific genes into neurons offers a potent approach for treatment of diseases as well as for the study of neuronal cell biology. Here we investigated the capabilities of cationic amino acid based lipid assemblies to act as nonviral gene delivery vectors in primary cultured neurons. An arginine-based lipid, Arg-C3-Glu2C14, and a lysine-based lipid, Lys-C3-Glu2C14, with two different types of counterion, chloride ion (Cl–) and trifluoroacetic acid (TFA–), were shown to successfully mediate transfection of primary cultured neurons with plasmid DNA encoding green fluorescent protein. Among four types of lipids, we optimized their conditions such as the lipid-to-DNA ratio and the amount of pDNA and conducted a cytotoxicity assay at the same time. Overall, Arg-C3-Glu2C14 with TFA– induced a rate of transfection in primary cultured neurons higher than that of Lys-C3-Glu2C14 using an optimal weight ratio of lipid-to-plasmid DNA of 1. Moreover, it was suggested that Arg-C3-Glu2C14 with TFA– showed the optimized value higher than that of Lipofectamine2000 in experimental conditions. Thus, Arg-C3-Glu2C14 with TFA– is a promising candidate as a reliable transfection reagent for primary cultured neurons with a relatively low cytotoxicity. PMID:24087930

Lipids of mitochondria.

PubMed

Horvath, Susanne E; Daum, Günther

2013-10-01

A unique organelle for studying membrane biochemistry is the mitochondrion whose functionality depends on a coordinated supply of proteins and lipids. Mitochondria are capable of synthesizing several lipids autonomously such as phosphatidylglycerol, cardiolipin and in part phosphatidylethanolamine, phosphatidic acid and CDP-diacylglycerol. Other mitochondrial membrane lipids such as phosphatidylcholine, phosphatidylserine, phosphatidylinositol, sterols and sphingolipids have to be imported. The mitochondrial lipid composition, the biosynthesis and the import of mitochondrial lipids as well as the regulation of these processes will be main issues of this review article. Furthermore, interactions of lipids and mitochondrial proteins which are highly important for various mitochondrial processes will be discussed. Malfunction or loss of enzymes involved in mitochondrial phospholipid biosynthesis lead to dysfunction of cell respiration, affect the assembly and stability of the mitochondrial protein import machinery and cause abnormal mitochondrial morphology or even lethality. Molecular aspects of these processes as well as diseases related to defects in the formation of mitochondrial membranes will be described. Copyright © 2013 Elsevier Ltd. All rights reserved.

Lipid14: The Amber Lipid Force Field

PubMed Central

2015-01-01

The AMBER lipid force field has been updated to create Lipid14, allowing tensionless simulation of a number of lipid types with the AMBER MD package. The modular nature of this force field allows numerous combinations of head and tail groups to create different lipid types, enabling the easy insertion of new lipid species. The Lennard-Jones and torsion parameters of both the head and tail groups have been revised and updated partial charges calculated. The force field has been validated by simulating bilayers of six different lipid types for a total of 0.5 μs each without applying a surface tension; with favorable comparison to experiment for properties such as area per lipid, volume per lipid, bilayer thickness, NMR order parameters, scattering data, and lipid lateral diffusion. As the derivation of this force field is consistent with the AMBER development philosophy, Lipid14 is compatible with the AMBER protein, nucleic acid, carbohydrate, and small molecule force fields. PMID:24803855

Lipid and polymeric carrier-mediated nucleic acid delivery

PubMed Central

Zhu, Lin; Mahato, Ram I

2010-01-01

Importance of the field Nucleic acids such as plasmid DNA, antisense oligonucleotide, and RNA interference (RNAi) molecules, have a great potential to be used as therapeutics for the treatment of various genetic and acquired diseases. To design a successful nucleic acid delivery system, the pharmacological effect of nucleic acids, the physiological condition of the subjects or sites, and the physicochemical properties of nucleic acid and carriers have to be thoroughly examined. Areas covered in this review The commonly used lipids, polymers and corresponding delivery systems are reviewed in terms of their characteristics, applications, advantages and limitations. What the reader will gain This article aims to provide an overview of biological barriers and strategies to overcome these barriers by properly designing effective synthetic carriers for nucleic acid delivery. Take home message A thorough understanding of biological barriers and the structure–activity relationship of lipid and polymeric carriers is the key for effective nucleic acid therapy. PMID:20836625

Adipocyte differentiation-related protein promotes lipid accumulation in goat mammary epithelial cells.

PubMed

Shi, H B; Yu, K; Luo, J; Li, J; Tian, H B; Zhu, J J; Sun, Y T; Yao, D W; Xu, H F; Shi, H P; Loor, J J

2015-10-01

Milk fat originates from the secretion of cytosolic lipid droplets (CLD) synthesized within mammary epithelial cells. Adipocyte differentiation-related protein (ADRP; gene symbol PLIN2) is a CLD-binding protein that is crucial for synthesis of mature CLD. Our hypothesis was that ADRP regulates CLD production and metabolism in goat mammary epithelial cells (GMEC) and thus plays a role in determining milk fat content. To understand the role of ADRP in ruminant milk fat metabolism, ADRP (PLIN2) was overexpressed or knocked down in GMEC using an adenovirus system. Immunocytochemical staining revealed that ADRP localized to the surface of CLD. Supplementation with oleic acid (OA) enhanced its colocalization with CLD surface and enhanced lipid accumulation. Overexpression of ADRP increased lipid accumulation and the concentration of triacylglycerol in GMEC. In contrast, morphological examination revealed that knockdown of ADRP decreased lipid accumulation even when OA was supplemented. This response was confirmed by the reduction in mass of cellular TG when ADRP was knocked down. The fact that knockdown of ADRP did not completely eliminate lipid accumulation at a morphological level in GMEC without OA suggests that some other compensatory factors may also aid in the process of CLD formation. The ADRP reversed the decrease of CLD accumulation induced by adipose triglyceride lipase. This is highly suggestive of ADRP promoting triacylglycerol stability within CLD by preventing access to adipose triglyceride lipase. Collectively, these data provide direct in vitro evidence that ADRP plays a key role in CLD formation and stability in GMEC. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Essential Fatty Acid Deficiency in 2015: The Impact of Novel Intravenous Lipid Emulsions.

PubMed

Gramlich, Leah; Meddings, Liisa; Alberda, Cathy; Wichansawakun, Sanit; Robbins, Sarah; Driscoll, David; Bistrian, Bruce

2015-09-01

The fatty acids, linoleic acid (18:2ω-6) and α-linolenic acid (18:3ω-3), are essential to the human diet. When these essential fatty acids are not provided in sufficient quantities, essential fatty acid deficiency (EFAD) develops. This can be suggested clinically by abnormal liver function tests or biochemically by an elevated Mead acid and reduced linoleic acid and arachidonic acid level, which is manifested as an elevated triene/tetraene ratio of Mead acid/arachidonic acid. Clinical features of EFAD may present later. With the introduction of novel intravenous (IV) lipid emulsions in North America, the proportion of fatty acids provided, particularly the essential fatty acids, varies substantially. We describe a case series of 3 complicated obese patients who were administered parenteral nutrition (PN), primarily using ClinOleic 20%, an olive oil-based lipid emulsion with reduced amounts of the essential fatty acids, linoleic and α-linolenic, compared with more conventional soybean oil emulsions throughout their hospital admission. Essential fatty acid profiles were obtained for each of these patients to investigate EFAD as a potential cause of abnormal liver enzymes. Although the profiles revealed reduced linoleic acid and elevated Mead acid levels, this was not indicative of the development of essential fatty acid deficiency, as reflected in the more definitive measure of triene/tetraene ratio. Instead, although the serum fatty acid panel reflected the markedly lower but still adequate dietary linoleic acid content and greatly increased oleic acid content in the parenteral lipid emulsion, the triene/tetraene ratio remained well below the level, indicating EFAD in each of these patients. The availability and use of new IV lipid emulsions in PN should encourage the clinician to review lipid metabolism based on the quantity of fatty acids provided in specific parenteral lipid emulsions and the expected impact of these lipid emulsions (with quite different

Advances on the Transfer of Lipids by Lipid Transfer Proteins.

PubMed

Wong, Louise H; Čopič, Alenka; Levine, Tim P

2017-07-01

Transfer of lipid across the cytoplasm is an essential process for intracellular lipid traffic. Lipid transfer proteins (LTPs) are defined by highly controlled in vitro experiments. The functional relevance of these is supported by evidence for the same reactions inside cells. Major advances in the LTP field have come from structural bioinformatics identifying new LTPs, and from the development of countercurrent models for LTPs. However, the ultimate aim is to unite in vitro and in vivo data, and this is where much progress remains to be made. Even where in vitro and in vivo experiments align, rates of transfer tend not to match. Here we set out some of the advances that might test how LTPs work. Copyright © 2017. Published by Elsevier Ltd.

Taurine supplemented plant protein based diets with alternative lipid sources for juvenile sea bream, sparus aurata

USDA-ARS?s Scientific Manuscript database

Two lipid sources were evaluated as fish oil replacements in fishmeal free, plant protein based diets for juvenile gilthead sea bream, Sparus aurata. A twelve week feeding study was undertaken to examine the performance of fish fed the diets with different sources of essential fatty acids (canola o...

Fluorescence study of protein-lipid complexes with a new symmetric squarylium probe.

PubMed

Ioffe, Valeriya M; Gorbenko, Galyna P; Deligeorgiev, Todor; Gadjev, Nikolai; Vasilev, Aleksey

2007-06-01

The novel symmetric squarylium derivative SQ-1 has been synthesized and tested for its sensitivity to the formation of protein-lipid complexes. SQ-1 binding to the model membranes composed of zwitterionic lipid phosphatidylcholine (PC) and its mixtures with anionic lipid cardiolipin (CL) in different molar ratios was found to be controlled mainly by hydrophobic interactions. Lysozyme (Lz) and ribonuclease A (RNase) exerted an influence on the probe association with lipid vesicles resulting presumably from the competition between SQ-1 and the proteins for bilayer free volume and modification of its properties. The magnitude of this effect was much higher for lysozyme which may stem from the amphipathy of protein alpha-helix involved in the membrane binding. Varying membrane composition provides evidence for the dye sensitivity to both hydrophobic and electrostatic protein-lipid interactions. Fluorescence anisotropy studies uncovered the restriction of SQ-1 rotational mobility in lipid environment in the presence of Lz and RNase being indicative of the incorporation of the proteins into bilayer interior. The results of binding, fluorescence quenching and kinetic experiments suggested lysozyme-induced local lipid demixing upon protein association with negatively charged membranes with threshold concentration of CL for the lipid demixing being 10 mol%.

Chalcones suppress fatty acid-induced lipid accumulation through a LKB1/AMPK signaling pathway in HepG2 cells.

PubMed

Zhang, Tianshun; Yamamoto, Norio; Ashida, Hitoshi

2014-06-01

Excessive lipid accumulation in the liver has been proposed to cause hyperlipidemia, diabetes and fatty liver disease. 4-Hydroxyderricin (4HD), xanthoangelol (XAG), cardamonin (CAR) and flavokawain B (FKB) are chalcones that have exhibited various biological effects against obesity, inflammation, and diabetes; however, little is known about the inhibitory effects of these chalcones on fatty liver disease. In the present study, we investigated the ability of 4HD, XAG, CAR, and FKB to reduce lipid accumulation in hepatocytes. When HepG2 cells were treated with a mixture of fatty acids (FAs; palmitic acid : oleic acid = 1 : 2 ratio), significant lipid accumulation was observed. Under the same experimental conditions, addition of chalcones at 5 μM significantly suppressed the FA-induced lipid accumulation. We found that the expression of sterol regulatory element-binding protein-1 (SREBP-1), a key molecule involved in lipogenesis, was decreased in these chalcone-treated cells. We also found that these chalcones increased the expression of peroxisome proliferator-activated receptor α (PPARα), which is involved in FA oxidation. Moreover, these chalcones increased phosphorylation of AMP-activated protein kinase (AMPK) and liver kinase B1 (LKB1), upstream regulators of SREBP-1 and PPARα. We confirmed that an AMPK inhibitor, compound C, reversed chalcone-induced changes in SREBP-1 and PPARα expression in the HepG2 cells. Collectively, we found that 4HD, XAG, CAR, and XAG attenuated lipid accumulation through activation of the LKB1/AMPK signaling pathway in HepG2 cells.

The pathogen-related yeast protein Pry1, a member of the CAP protein superfamily, is a fatty acid-binding protein

PubMed Central

Darwiche, Rabih; Mène-Saffrané, Laurent; Gfeller, David; Asojo, Oluwatoyin A.; Schneiter, Roger

2017-01-01

Members of the CAP superfamily (cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins), also known as SCP superfamily (sperm-coating proteins), have been implicated in many physiological processes, including immune defenses, venom toxicity, and sperm maturation. Their mode of action, however, remains poorly understood. Three proteins of the CAP superfamily, Pry1, -2, and -3 (pathogen related in yeast), are encoded in the Saccharomyces cerevisiae genome. We have shown previously that Pry1 binds cholesterol in vitro and that Pry function is required for sterol secretion in yeast cells, indicating that members of this superfamily may generally bind sterols or related small hydrophobic compounds. On the other hand, tablysin-15, a CAP protein from the horsefly Tabanus yao, has been shown to bind leukotrienes and free fatty acids in vitro. Therefore, here we assessed whether the yeast Pry1 protein binds fatty acids. Computational modeling and site-directed mutagenesis indicated that the mode of fatty acid binding is conserved between tablysin-15 and Pry1. Pry1 bound fatty acids with micromolar affinity in vitro, and its function was essential for fatty acid export in cells lacking the acyl-CoA synthetases Faa1 and Faa4. Fatty acid binding of Pry1 is independent of its capacity to bind sterols, and the two sterol- and fatty acid-binding sites are nonoverlapping. These results indicate that some CAP family members, such as Pry1, can bind different lipids, particularly sterols and fatty acids, at distinct binding sites, suggesting that the CAP domain may serve as a stable, secreted protein domain that can accommodate multiple ligand-binding sites. PMID:28365570

Altering the Mitochondrial Fatty Acid Synthesis (mtFASII) Pathway Modulates Cellular Metabolic States and Bioactive Lipid Profiles as Revealed by Metabolomic Profiling

PubMed Central

Clay, Hayley B.; Parl, Angelika K.; Mitchell, Sabrina L.; Singh, Larry; Bell, Lauren N.; Murdock, Deborah G.

2016-01-01

Despite the presence of a cytosolic fatty acid synthesis pathway, mitochondria have retained their own means of creating fatty acids via the mitochondrial fatty acid synthesis (mtFASII) pathway. The reason for its conservation has not yet been elucidated. Therefore, to better understand the role of mtFASII in the cell, we used thin layer chromatography to characterize the contribution of the mtFASII pathway to the fatty acid composition of selected mitochondrial lipids. Next, we performed metabolomic analysis on HeLa cells in which the mtFASII pathway was either hypofunctional (through knockdown of mitochondrial acyl carrier protein, ACP) or hyperfunctional (through overexpression of mitochondrial enoyl-CoA reductase, MECR). Our results indicate that the mtFASII pathway contributes little to the fatty acid composition of mitochondrial lipid species examined. Additionally, loss of mtFASII function results in changes in biochemical pathways suggesting alterations in glucose utilization and redox state. Interestingly, levels of bioactive lipids, including lysophospholipids and sphingolipids, directly correlate with mtFASII function, indicating that mtFASII may be involved in the regulation of bioactive lipid levels. Regulation of bioactive lipid levels by mtFASII implicates the pathway as a mediator of intracellular signaling. PMID:26963735

Oral delivery of peptides and proteins using lipid-based drug delivery systems.

PubMed

Li, Ping; Nielsen, Hanne Mørck; Müllertz, Anette

2012-10-01

In order to successfully develop lipid-based drug delivery systems (DDS) for oral administration of peptides and proteins, it is important to gain an understanding of the colloid structures formed by these DDS, the mode of peptide and protein incorporation as well as the mechanism by which intestinal absorption of peptides and proteins is promoted. The present paper reviews the literature on lipid-based DDS, employed for oral delivery of peptides and proteins and highlights the mechanisms by which the different lipid-based carriers are expected to overcome the two most important barriers (extensive enzymatic degradation and poor transmucosal permeability). This paper also gives a clear-cut idea about advantages and drawbacks of using different lipidic colloidal carriers ((micro)emulsions, solid lipid core particles and liposomes) for oral delivery of peptides and proteins. Lipid-based DDS are safe and suitable for oral delivery of peptides and proteins. Significant progress has been made in this area with several technologies on clinical trials. However, a better understanding of the mechanism of action in vivo is needed in order to improve the design and development of lipid-based DDS with the desired bioavailability and therapeutic profile.

Homocysteine regulates fatty acid and lipid metabolism in yeast.

PubMed

Visram, Myriam; Radulovic, Maja; Steiner, Sabine; Malanovic, Nermina; Eichmann, Thomas O; Wolinski, Heimo; Rechberger, Gerald N; Tehlivets, Oksana

2018-04-13

S -Adenosyl-l-homocysteine hydrolase (AdoHcy hydrolase; Sah1 in yeast/AHCY in mammals) degrades AdoHcy, a by-product and strong product inhibitor of S -adenosyl-l-methionine (AdoMet)-dependent methylation reactions, to adenosine and homocysteine (Hcy). This reaction is reversible, so any elevation of Hcy levels, such as in hyperhomocysteinemia (HHcy), drives the formation of AdoHcy, with detrimental consequences for cellular methylation reactions. HHcy, a pathological condition linked to cardiovascular and neurological disorders, as well as fatty liver among others, is associated with a deregulation of lipid metabolism. Here, we developed a yeast model of HHcy to identify mechanisms that dysregulate lipid metabolism. Hcy supplementation to wildtype cells up-regulated cellular fatty acid and triacylglycerol content and induced a shift in fatty acid composition, similar to changes observed in mutants lacking Sah1. Expression of the irreversible bacterial pathway for AdoHcy degradation in yeast allowed us to dissect the impact of AdoHcy accumulation on lipid metabolism from the impact of elevated Hcy. Expression of this pathway fully suppressed the growth deficit of sah1 mutants as well as the deregulation of lipid metabolism in both the sah1 mutant and Hcy-exposed wildtype, showing that AdoHcy accumulation mediates the deregulation of lipid metabolism in response to elevated Hcy in yeast. Furthermore, Hcy supplementation in yeast led to increased resistance to cerulenin, an inhibitor of fatty acid synthase, as well as to a concomitant decline of condensing enzymes involved in very long-chain fatty acid synthesis, in line with the observed shift in fatty acid content and composition. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Homocysteine regulates fatty acid and lipid metabolism in yeast

PubMed Central

Visram, Myriam; Radulovic, Maja; Steiner, Sabine; Malanovic, Nermina; Eichmann, Thomas O.; Wolinski, Heimo; Rechberger, Gerald N.; Tehlivets, Oksana

2018-01-01

S-Adenosyl-l-homocysteine hydrolase (AdoHcy hydrolase; Sah1 in yeast/AHCY in mammals) degrades AdoHcy, a by-product and strong product inhibitor of S-adenosyl-l-methionine (AdoMet)-dependent methylation reactions, to adenosine and homocysteine (Hcy). This reaction is reversible, so any elevation of Hcy levels, such as in hyperhomocysteinemia (HHcy), drives the formation of AdoHcy, with detrimental consequences for cellular methylation reactions. HHcy, a pathological condition linked to cardiovascular and neurological disorders, as well as fatty liver among others, is associated with a deregulation of lipid metabolism. Here, we developed a yeast model of HHcy to identify mechanisms that dysregulate lipid metabolism. Hcy supplementation to wildtype cells up-regulated cellular fatty acid and triacylglycerol content and induced a shift in fatty acid composition, similar to changes observed in mutants lacking Sah1. Expression of the irreversible bacterial pathway for AdoHcy degradation in yeast allowed us to dissect the impact of AdoHcy accumulation on lipid metabolism from the impact of elevated Hcy. Expression of this pathway fully suppressed the growth deficit of sah1 mutants as well as the deregulation of lipid metabolism in both the sah1 mutant and Hcy-exposed wildtype, showing that AdoHcy accumulation mediates the deregulation of lipid metabolism in response to elevated Hcy in yeast. Furthermore, Hcy supplementation in yeast led to increased resistance to cerulenin, an inhibitor of fatty acid synthase, as well as to a concomitant decline of condensing enzymes involved in very long-chain fatty acid synthesis, in line with the observed shift in fatty acid content and composition. PMID:29414770

Association of canalicular membrane enzymes with bile acid micelles and lipid aggregates in human and rat bile.

PubMed

Accatino, L; Pizarro, M; Solís, N; Koenig, C S

1995-01-18

This study was undertaken to gain insights into the characteristics of the polymolecular association between canalicular membrane enzymes, bile acids, cholesterol and phospholipids in bile and into the celular mechanisms whereby the enzymes are secreted into bile. With this purpose, we studied the distribution of bile acids, cholesterol, phospholipids, proteins and representative canalicular membrane enzymes (alkaline phosphatase, 5'-nucleotidase and gamma-glutamyl transpeptidase), which can be considered specific marker constituents, in bile fractions enriched in phospholipid-cholesterol lamellar structures (multilamellar and unilamellar vesicles) and bile acid-mixed micelles. These fractions were isolated by ultracentrifugation from human hepatic bile, normal rat bile and bile of rats treated with diosgenin, a steroid that induces a marked increase in biliary cholesterol secretion, and were characterized by density, lipid composition and transmission electron microscopy. These studies demonstrate that alkaline phosphatase, 5'-nucleotidase and gamma-glutamyl transpeptidase are secreted into both human and rat bile where they are preferentially associated with bile acid-mixed micelles, suggesting a role for bile acids in both release of these enzymes and lipids from the canalicular membrane and solubilization in bile. In addition, heterogeneous association of these enzymes with nonmicellar, lamellar structures in human and rat bile is consistent with the hypothesis that processes independent of the detergent effects of bile acids might also result in the release of specific intrinsic membrane proteins into bile.

Linoleic Acid-Induced Ultra-Weak Photon Emission from Chlamydomonas reinhardtii as a Tool for Monitoring of Lipid Peroxidation in the Cell Membranes

PubMed Central

Prasad, Ankush; Pospíšil, Pavel

2011-01-01

Reactive oxygen species formed as a response to various abiotic and biotic stresses cause an oxidative damage of cellular component such are lipids, proteins and nucleic acids. Lipid peroxidation is considered as one of the major processes responsible for the oxidative damage of the polyunsaturated fatty acid in the cell membranes. Various methods such as a loss of polyunsaturated fatty acids, amount of the primary and the secondary products are used to monitor the level of lipid peroxidation. To investigate the use of ultra-weak photon emission as a non-invasive tool for monitoring of lipid peroxidation, the involvement of lipid peroxidation in ultra-weak photon emission was studied in the unicellular green alga Chlamydomonas reinhardtii. Lipid peroxidation initiated by addition of exogenous linoleic acid to the cells was monitored by ultra-weak photon emission measured with the employment of highly sensitive charged couple device camera and photomultiplier tube. It was found that the addition of linoleic acid to the cells significantly increased the ultra-weak photon emission that correlates with the accumulation of lipid peroxidation product as measured using thiobarbituric acid assay. Scavenging of hydroxyl radical by mannitol, inhibition of intrinsic lipoxygenase by catechol and removal of molecular oxygen considerably suppressed ultra-weak photon emission measured after the addition of linoleic acid. The photon emission dominated at the red region of the spectrum with emission maximum at 680 nm. These observations reveal that the oxidation of linoleic acid by hydroxyl radical and intrinsic lipoxygenase results in the ultra-weak photon emission. Electronically excited species such as excited triplet carbonyls are the likely candidates for the primary excited species formed during the lipid peroxidation, whereas chlorophylls are the final emitters of photons. We propose here that the ultra-weak photon emission can be used as a non-invasive tool for the

Feeding-fasting dependent recruitment of membrane microdomain proteins to lipid droplets purified from the liver.

PubMed

Sadh, Kritika; Rai, Priyanka; Mallik, Roop

2017-01-01

Lipid droplets (LDs) are cellular stores of neutral fat that facilitate lipid and protein trafficking in response to metabolic cues. Unlike other vesicles, the phospholipid membrane on the LD is a monolayer. Interestingly, this monolayer membrane has free cholesterol, and may therefore contain lipid microdomains that serve as a platform for assembling proteins involved in signal transduction, cell polarity, pathogen entry etc. In support of this, cell culture studies have detected microdomain-associated "raftophilic" proteins on LDs. However, the physiological significance of this observation has been unclear. Here we show that two proteins (Flotillin-1 and SNAP23) that bind to membrane microdomains associate differently with LDs purified from rat liver depending on the feeding/fasting state of the animal. Flotillin-1 increases on LDs in the fed state, possibly because LDs interact with the endoplasmic reticulum (ER), facilitating supply of flotillin-1 from ER to LDs. Interestingly, this increase in flotillin-1 is correlated with an increase in free cholesterol on the LDs in fed state. In opposite behaviour to flotillin-1, SNAP23 increases on LDs in the fasted state and this appears to mediate LD-mitochondria interactions. Such LD-mitochondria interactions may provide fatty acids to mitochondria for promoting beta-oxidation in hepatocytes in response to fasting. Our work brings out physiologically relevant aspects of lipid droplet biology that are different from, and may not be entirely possible to replicate and study in cell culture.

Keap1-Knockdown Decreases Fasting-Induced Fatty Liver via Altered Lipid Metabolism and Decreased Fatty Acid Mobilization from Adipose Tissue

PubMed Central

Xu, Jialin; Donepudi, Ajay C.; Moscovitz, Jamie E.; Slitt, Angela L.

2013-01-01

Aims The purpose of this study was to determine whether Nrf2 activation, via Keap1-knockdown (Keap1-KD), regulates lipid metabolism and mobilization induced by food deprivation (e.g. fasting). Methods and Results Male C57BL/6 (WT) and Keap1-KD mice were either fed ad libitum or food deprived for 24 hours. After fasting, WT mice exhibited a marked increase in hepatic lipid accumulation, but Keap1-KD mice had an attenuated increase of lipid accumulation, along with reduced expression of lipogenic genes (acetyl-coA carboxylase, stearoyl-CoA desaturase-1, and fatty acid synthase) and reduced expression of genes related to fatty acid transport, such as fatty acid translocase/CD36 (CD36) and Fatty acid transport protein (FATP) 2, which may attribute to the reduced induction of Peroxisome proliferator-activated receptor (Ppar) α signaling in the liver. Additionally, enhanced Nrf2 activity by Keap1-KD increased AMP-activated protein kinase (AMPK) phosphorylation in liver. In white adipose tissue, enhanced Nrf2 activity did not change the lipolysis rate by fasting, but reduced expression of fatty acid transporters — CD36 and FATP1, via a PPARα-dependent mechanism, which impaired fatty acid transport from white adipose tissue to periphery circulation system, and resulted in increased white adipose tissue fatty acid content. Moreover, enhanced Nrf2 activity increased glucose tolerance and Akt phosphorylation levels upon insulin administration, suggesting Nrf2 signaling pathway plays a key role in regulating insulin signaling and enhanced insulin sensitivity in skeletal muscle. Conclusion Enhanced Nrf2 activity via Keap1-KD decreased fasting-induced steatosis, pointing to an important function of Nrf2 on lipid metabolism under the condition of nutrient deprivation. PMID:24224011

Alpha-Lipoic Acid Alleviates Acute Inflammation and Promotes Lipid Mobilization During the Inflammatory Response in White Adipose Tissue of Mice.

PubMed

Guo, Jun; Gao, Shixing; Liu, Zhiqing; Zhao, Ruqian; Yang, Xiaojing

2016-10-01

Recently, white adipose tissue has been shown to exhibit immunological activity, and may play an important role in host defense and protection against bacterial infection. Αlpha-lipoic acid (α-LA) has been demonstrated to function as an anti-inflammatory and anti-oxidant agent. However, its influence on the inflammatory response and metabolic changes in white adipose tissue remains unknown. We used male C57BL/6 mice as models to study the effect of α-LA on the inflammatory response and metabolic changes in white adipose tissue after stimulation with lipopolysaccharide (LPS). The non-esterified fatty acid content was measured by an automatic biochemical analyzer. The expression of inflammation-, lipid- and energy metabolism-related genes and proteins was determined by quantitative real-time polymerase chain reaction and western blotting. The results indicated that α-LA significantly decreased the epididymis fat weight index and the non-esterified fatty acid content in plasma compared with the control group. LPS significantly increased the expression of inflammation genes and α-LA reduced their expression. The LPS-induced expression of nuclear factor-κB protein was decreased by α-LA. Regarding lipid metabolism, α-LA significantly counteracted the inhibitory effects of LPS on the expression of hormone-sensitive lipase gene and protein. α-LA evidently increased the gene expression of fatty acid transport protein 1 and cluster of differentiation 36. Regarding energy metabolism, α-LA significantly increased the expression of most of mitochondrial DNA-encoded genes compared with the control and LPS group. Accordingly, α-LA can alleviate acute inflammatory response and this action may be related with the promotion of lipid mobilization in white adipose tissue.

Lipid and fatty acid composition microalgae Chlorella vulgaris using photobioreactor and open pond

NASA Astrophysics Data System (ADS)

Jay, M. I.; Kawaroe, M.; Effendi, H.

2018-03-01

Microalgae contain lipids and fatty acids that can be the raw materials of biofuel. Previous studies have been known of using cultivation systems to obtain biomass of C. vulgaris which can be extracted to obtain lipid and fatty acid content. The observational step was observed ten days in photobioreactor and open pond for harvesting biomass using NaOH, lipid extraction using hexane and methanol, and fatty acid analysis using Gas Chromatography. Lipid content of microalgae biomass in photobioreactor and open pond was 2.26 ± 0.51% and 3.18 ± 0.80%, respectively. Fatty acid content ranged between 0.7-22.8% and 0.9-22.6% and the dominant fatty acids in both cultivating system was palmitic acid.

Fatty acid methyl ester profiles of bat wing surface lipids.

PubMed

Pannkuk, Evan L; Fuller, Nathan W; Moore, Patrick R; Gilmore, David F; Savary, Brett J; Risch, Thomas S

2014-11-01

Sebocytes are specialized epithelial cells that rupture to secrete sebaceous lipids (sebum) across the mammalian integument. Sebum protects the integument from UV radiation, and maintains host microbial communities among other functions. Native glandular sebum is composed primarily of triacylglycerides (TAG) and wax esters (WE). Upon secretion (mature sebum), these lipids combine with minor cellular membrane components comprising total surface lipids. TAG and WE are further cleaved to smaller molecules through oxidation or host enzymatic digestion, resulting in a complex mixture of glycerolipids (e.g., TAG), sterols, unesterified fatty acids (FFA), WE, cholesteryl esters, and squalene comprising surface lipid. We are interested if fatty acid methyl ester (FAME) profiling of bat surface lipid could predict species specificity to the cutaneous fungal disease, white nose syndrome (WNS). We collected sebaceous secretions from 13 bat spp. using Sebutape(®) and converted them to FAME with an acid catalyzed transesterification. We found that Sebutape(®) adhesive patches removed ~6× more total lipid than Sebutape(®) indicator strips. Juvenile eastern red bats (Lasiurus borealis) had significantly higher 18:1 than adults, but 14:0, 16:1, and 20:0 were higher in adults. FAME profiles among several bat species were similar. We concluded that bat surface lipid FAME profiling does not provide a robust model predicting species susceptibility to WNS. However, these results provide baseline data that can be used for lipid roles in future ecological studies, such as life history, diet, or migration.

Solubilization of lipids and lipid phases by the styrene-maleic acid copolymer.

PubMed

Dominguez Pardo, Juan J; Dörr, Jonas M; Iyer, Aditya; Cox, Ruud C; Scheidelaar, Stefan; Koorengevel, Martijn C; Subramaniam, Vinod; Killian, J Antoinette

2017-01-01

A promising tool in membrane research is the use of the styrene-maleic acid (SMA) copolymer to solubilize membranes in the form of nanodiscs. Since membranes are heterogeneous in composition, it is important to know whether SMA thereby has a preference for solubilization of either specific types of lipids or specific bilayer phases. Here, we investigated this by performing partial solubilization of model membranes and analyzing the lipid composition of the solubilized fraction. We found that SMA displays no significant lipid preference in homogeneous binary lipid mixtures in the fluid phase, even when using lipids that by themselves show very different solubilization kinetics. By contrast, in heterogeneous phase-separated bilayers, SMA was found to have a strong preference for solubilization of lipids in the fluid phase as compared to those in either a gel phase or a liquid-ordered phase. Together the results suggest that (1) SMA is a reliable tool to characterize native interactions between membrane constituents, (2) any solubilization preference of SMA is not due to properties of individual lipids but rather due to properties of the membrane or membrane domains in which these lipids reside and (3) exploiting SMA resistance rather than detergent resistance may be an attractive approach for the isolation of ordered domains from biological membranes.

Lipid domains control myelin basic protein adsorption and membrane interactions between model myelin lipid bilayers

PubMed Central

Lee, Dong Woog; Banquy, Xavier; Kristiansen, Kai; Kaufman, Yair; Boggs, Joan M.; Israelachvili, Jacob N.

2014-01-01

The surface forces apparatus and atomic force microscope were used to study the effects of lipid composition and concentrations of myelin basic protein (MBP) on the structure of model lipid bilayers, as well as the interaction forces and adhesion between them. The lipid bilayers had a lipid composition characteristic of the cytoplasmic leaflets of myelin from “normal” (healthy) and “disease-like” [experimental allergic encephalomyelitis (EAE)] animals. They showed significant differences in the adsorption mechanism of MBP. MBP adsorbs on normal bilayers to form a compact film (3–4 nm) with strong intermembrane adhesion (∼0.36 mJ/m2), in contrast to its formation of thicker (7–8 nm) swelled films with weaker intermembrane adhesion (∼0.13 mJ/m2) on EAE bilayers. MBP preferentially adsorbs to liquid-disordered submicron domains within the lipid membranes, attributed to hydrophobic attractions. These results show a direct connection between the lipid composition of membranes and membrane–protein adsorption mechanisms that affects intermembrane spacing and adhesion and has direct implications for demyelinating diseases. PMID:24516125

Argininosuccinate synthetase regulates hepatic AMPK linking protein catabolism and ureagenesis to hepatic lipid metabolism

PubMed Central

Madiraju, Anila K.; Alves, Tiago; Zhao, Xiaojian; Cline, Gary W.; Zhang, Dongyan; Bhanot, Sanjay; Samuel, Varman T.; Kibbey, Richard G.; Shulman, Gerald I.

2016-01-01

A key sensor of cellular energy status, AMP-activated protein kinase (AMPK), interacts allosterically with AMP to maintain an active state. When active, AMPK triggers a metabolic switch, decreasing the activity of anabolic pathways and enhancing catabolic processes such as lipid oxidation to restore the energy balance. Unlike oxidative tissues, in which AMP is generated from adenylate kinase during states of high energy demand, the ornithine cycle enzyme argininosuccinate synthetase (ASS) is a principle site of AMP generation in the liver. Here we show that ASS regulates hepatic AMPK, revealing a central role for ureagenesis flux in the regulation of metabolism via AMPK. Treatment of primary rat hepatocytes with amino acids increased gluconeogenesis and ureagenesis and, despite nutrient excess, induced both AMPK and acetyl-CoA carboxylase (ACC) phosphorylation. Antisense oligonucleotide knockdown of hepatic ASS1 expression in vivo decreased liver AMPK activation, phosphorylation of ACC, and plasma β-hydroxybutyrate concentrations. Taken together these studies demonstrate that increased amino acid flux can activate AMPK through increased AMP generated by ASS, thus providing a novel link between protein catabolism, ureagenesis, and hepatic lipid metabolism. PMID:27247419

A Salmon Protein Hydrolysate Exerts Lipid-Independent Anti-Atherosclerotic Activity in ApoE-Deficient Mice

PubMed Central

Busnelli, Marco; Bjørndal, Bodil; Holm, Sverre; Brattelid, Trond; Manzini, Stefano; Ganzetti, Giulia S.; Dellera, Federica; Halvorsen, Bente; Aukrust, Pål; Sirtori, Cesare R.; Nordrehaug, Jan E.; Skorve, Jon; Berge, Rolf K.; Chiesa, Giulia

2014-01-01

Fish consumption is considered health beneficial as it decreases cardiovascular disease (CVD)-risk through effects on plasma lipids and inflammation. We investigated a salmon protein hydrolysate (SPH) that is hypothesized to influence lipid metabolism and to have anti-atherosclerotic and anti-inflammatory properties. 24 female apolipoprotein (apo) E−/− mice were divided into two groups and fed a high-fat diet with or without 5% (w/w) SPH for 12 weeks. The atherosclerotic plaque area in aortic sinus and arch, plasma lipid profile, fatty acid composition, hepatic enzyme activities and gene expression were determined. A significantly reduced atherosclerotic plaque area in the aortic arch and aortic sinus was found in the 12 apoE−/− mice fed 5% SPH for 12 weeks compared to the 12 casein-fed control mice. Immunohistochemical characterization of atherosclerotic lesions in aortic sinus displayed no differences in plaque composition between mice fed SPH compared to controls. However, reduced mRNA level of Icam1 in the aortic arch was found. The plasma content of arachidonic acid (C20∶4n-6) and oleic acid (C18∶1n-9) were increased and decreased, respectively. SPH-feeding decreased the plasma concentration of IL-1β, IL-6, TNF-α and GM-CSF, whereas plasma cholesterol and triacylglycerols (TAG) were unchanged, accompanied by unchanged mitochondrial fatty acid oxidation and acyl-CoA:cholesterol acyltransferase (ACAT)-activity. These data show that a 5% (w/w) SPH diet reduces atherosclerosis in apoE−/− mice and attenuate risk factors related to atherosclerotic disorders by acting both at vascular and systemic levels, and not directly related to changes in plasma lipids or fatty acids. PMID:24840793

Identification of trapped and boundary lipid binding sites in M13 coat protein/lipid complexes by deuterium NMR spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Gorkom, L.C.; Horvath, L.I.; Hemminga, M.A.

The major coat protein of M13 bacteriophage has been incorporated into bilayers of 1,2-dimyristoyl-sn-glycero-3-phosphocholine, deuterated in the trimethyl segments of the choline headgroup (DMPC-d9). Two-component deuterium and phosphorus-31 NMR spectra have been observed from bilayer complexes containing the coat protein, indicating slow exchange (on the deuterium quadrupole anisotropy and phosphorus-31 chemical shift averaging time scales) of lipid molecules of less than 10(3) Hz between two motionally distinct environments in the complexes. The fraction of the isotropic spectral component increases with increasing M13 protein concentration, and this component is attributed to lipid headgroups, which are disordered relative to their order inmore » protein-free bilayers. The activation energy of the fast local motions of the trimethyl groups of the choline residue in the headgroup decreases from 23 kJ mol-1 in the pure lipid bilayers to 20 kJ mol-1 for the protein-associated lipid headgroups. The chemical exchange rate of lipid molecules between the two motionally distinct environments has been estimated to be 20-50 Hz by steady-state line-shape simulations of the deuterium spectra of DMPC-d9/M13 coat protein complexes using exchange-coupled modified Bloch equations. The off-rate was, as expected from one-to-one exchange, independent of the L/P ratio; tau off -1 = 0.23 kHz. It is suggested that the protein-associated lipid may be trapped between closely packed parallel aggregates of M13 coat protein and that the high local concentration of protein in a one-dimensional arrangement in lipid bilayers may be required for the fast reassembly of phage particles before release from an infected cell.« less

FATTY ACID DESATURASE4 of Arabidopsis encodes a protein distinct from characterized fatty acid desaturases.

PubMed

Gao, Jinpeng; Ajjawi, Imad; Manoli, Arthur; Sawin, Andrew; Xu, Changcheng; Froehlich, John E; Last, Robert L; Benning, Christoph

2009-12-01

Polar membrane glycerolipids occur in a mixture of molecular species defined by a polar head group and characteristic acyl groups esterified to a glycerol backbone. A molecular species of phosphatidylglycerol specific to chloroplasts of plants carries a Delta(3-trans) hexadecenoic acid in the sn-2 position of its core glyceryl moiety. The fad4-1 mutant of Arabidopsis thaliana missing this particular phosphatidylglycerol molecular species lacks the necessary fatty acid desaturase, or a component thereof. The overwhelming majority of acyl groups associated with membrane lipids in plants contains double bonds with a cis configuration. However, FAD4 is unusual because it is involved in the formation of a trans double bond introduced close to the carboxyl group of palmitic acid, which is specifically esterified to the sn-2 glyceryl carbon of phosphatidylglycerol. As a first step towards the analysis of this unusual desaturase reaction, the FAD4 gene was identified by mapping of the FAD4 locus and coexpression analysis with known lipid genes. FAD4 encodes a predicted integral membrane protein that appears to be unrelated to classic membrane bound fatty acid desaturases based on overall sequence conservation. However, the FAD4 protein contains two histidine motifs resembling those of metalloproteins such as fatty acid desaturases. FAD4 is targeted to the plastid. Overexpression of the cDNA in transgenic Arabidopsis led to increased accumulation of the Delta(3-trans) hexadecanoyl group in phosphatidylglycerol relative to wild type. Taken together these results are consistent with the hypothesis that FAD4 is the founding member of a novel class of fatty acid desaturases.

Hyodeoxycholic acid derivatives as liver X receptor α and G-protein-coupled bile acid receptor agonists

NASA Astrophysics Data System (ADS)

de Marino, Simona; Carino, Adriana; Masullo, Dario; Finamore, Claudia; Marchianò, Silvia; Cipriani, Sabrina; di Leva, Francesco Saverio; Catalanotti, Bruno; Novellino, Ettore; Limongelli, Vittorio; Fiorucci, Stefano; Zampella, Angela

2017-02-01

Bile acids are extensively investigated for their potential in the treatment of human disorders. The liver X receptors (LXRs), activated by oxysterols and by a secondary bile acid named hyodeoxycholic acid (HDCA), have been found essential in the regulation of lipid homeostasis in mammals. Unfortunately, LXRα activates lipogenic enzymes causing accumulation of lipid in the liver. In addition to LXRs, HDCA has been also shown to function as ligand for GPBAR1, a G protein coupled receptor for secondary bile acids whose activation represents a promising approach to liver steatosis. In the present study, we report a library of HDCA derivatives endowed with modulatory activity on the two receptors. The lead optimization of HDCA moiety was rationally driven by the structural information on the binding site of the two targets and results from pharmacological characterization allowed the identification of hyodeoxycholane derivatives with selective agonistic activity toward LXRα and GPBAR1 and notably to the identification of the first example of potent dual LXRα/GPBAR1 agonists. The new chemical entities might hold utility in the treatment of dyslipidemic disorders.

Phosphatidic Acid and Lipid Sensing by mTOR

PubMed Central

Foster, David A.

2013-01-01

Mammalian target of rapamycin (mTOR) has been implicated as a sensor of nutrient sufficiency for dividing cells and is activated by essential amino acids and glucose. However, cells also require lipids for membrane biosynthesis. A central metabolite in the synthesis of membrane phospholipids is phosphatidic acid (PA), which is required for the stability and activity of mTOR complexes. While PA is commonly generated by the phospholipase D-catalyzed hydrolysis of phosphatidylcholine, PA is also generated by diacylglycerol kinases and lysophosphatidic acid acyltransferases, which are at the center of phospholipid biosynthesis. It is proposed that the responsiveness of mTOR/TOR to PA evolved as a means for sensing lipid precursors for membrane biosynthesis prior to doubling the mass of a cell and dividing. PMID:23507202

Colour, lipid and protein stability of Rhea americana meat during air- and vacuum-packaged storage: influence of muscle on oxidative processes.

PubMed

Filgueras, R S; Gatellier, P; Aubry, L; Thomas, A; Bauchart, D; Durand, D; Zambiazi, R C; Santé-Lhoutellier, V

2010-11-01

Physicochemical characteristics and oxidative stability during storage were determined in Gastrocnemius pars interna (GN) and Iliofiburalis (IF) muscles of Rhea americana. Glycolytic potential (GP) and pH decline of muscles were measured within the first 24 h post mortem. Colour, lipid and protein stability were determined during storage of meat, i.e. 5 days under air-packaging at 4°C, or 28 days under vacuum-packaging at 4°C. In parallel, anti-oxidant status of muscles was estimated by measuring α-tocopherol content and anti-oxidant enzyme activities (superoxide dismutase and catalase), while pro-oxidant status was evaluated by determining haeminic iron and long chain fatty acids (especially polyunsaturated fatty acids). The ultimate pH was similar in both muscles, but the GP value was significantly higher in IF than in GN muscle. Haeminic iron and alpha-tocopherol content differed between muscles, with 30% more haeminic iron (p<0.05) and 134% more alpha-tocopherol (p<0.001) in IF than GN muscle. The IF muscle presented higher lipid content and lower PUFA/SFA ratio (polyunsaturated fatty acids/saturated fatty acids) than GN muscle. With storage under air-packaging, lipid and protein oxidation of rhea muscles increased up to 275% and 30%, respectively. This increase was more rapidly and marked in IF muscle. The IF also showed high level of metmyoglobin accumulation after 3 days of storage (47%) and was rejected by 1 consumer out of 2 in sensorial analysis. Under vacuum-packaging, both muscles showed a high stability of colour and no oxidation of lipids and proteins. Copyright © 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.

Effects of ligand binding on the dynamics of rice nonspecific lipid transfer protein 1: a model from molecular simulations.

PubMed

Lai, Yen-Ting; Cheng, Chao-Sheng; Liu, Yu-Nan; Liu, Yaw-Jen; Lyu, Ping-Chiang

2008-09-01

Plant nonspecific lipid transfer proteins (nsLTPs) are small, basic proteins constituted mainly of alpha-helices and stabilized by four conserved disulfide bridges. They are characterized by the presence of a tunnel-like hydrophobic cavity, capable of transferring various lipid molecules between lipid bilayers in vitro. In this study, molecular dynamics (MD) simulations were performed at room temperature to investigate the effects of lipid binding on the dynamic properties of rice nsLTP1. Rice nsLTP1, either in the free form or complexed with one or two lipids was subjected to MD simulations. The C-terminal loop was very flexible both before and after lipid binding, as revealed by calculating the root-mean-square fluctuation. After lipid binding, the flexibility of some residues that were not in direct contact with lipid molecules increased significantly, indicating an increase of entropy in the region distal from the binding site. Essential dynamics analysis revealed clear differences in motion between unliganded and liganded rice nsLTP1s. In the free form of rice nsLTP1, loop1 exhibited the largest directional motion. This specific essential motion mode diminished after binding one or two lipid molecules. To verify the origin of the essential motion observed in the free form of rice nsLTP1, we performed multiple sequence alignments to probe the intrinsic motion encoded in the primary sequence. We found that the amino acid sequence of loop1 is highly conserved among plant nsLTP1s, thus revealing its functional importance during evolution. Furthermore, the sequence of loop1 is composed mainly of amino acids with short side chains. In this study, we show that MD simulations, together with essential dynamics analysis, can be used to determine structural and dynamic differences of rice nsLTP1 upon lipid binding. 2008 Wiley-Liss, Inc.

Proteomics analysis of high lipid-producing strain Mucor circinelloides WJ11: an explanation for the mechanism of lipid accumulation at the proteomic level.

PubMed

Tang, Xin; Zan, Xinyi; Zhao, Lina; Chen, Haiqin; Chen, Yong Q; Chen, Wei; Song, Yuanda; Ratledge, Colin

2016-02-11

The oleaginous fungus, Mucor circinelloides, is attracting considerable interest as it produces oil rich in γ-linolenic acid. Nitrogen (N) deficiency is a common strategy to trigger the lipid accumulation in oleaginous microorganisms. Although a simple pathway from N depletion in the medium to lipid accumulation has been elucidated at the enzymatic level, global changes at protein levels upon N depletion have not been investigated. In this study, we have systematically analyzed the changes at the levels of protein expression in M. circinelloides WJ11, a high lipid-producing strain (36 %, lipid/cell dry weight), during lipid accumulation. Proteomic analysis demonstrated that N depletion increased the expression of glutamine synthetase, involved in ammonia assimilation, for the supply of cellular nitrogen but decreased the metabolism of amino acids. Upon N deficiency, many proteins (e.g., fructose-bisphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase, enolase, pyruvate kinase) involved in glycolytic pathway were up-regulated while proteins involved in the tricarboxylic acid cycle (e.g., isocitrate dehydrogenase, succinyl-CoA ligase, succinate dehydrogenase, fumarate hydratase) were down-regulated, indicating this activity was retarded thereby leading to a greater flux of carbon into fatty acid biosynthesis. Moreover, glucose-6-phosphate dehydrogenase, transaldolase and transketolase, which participate in the pentose phosphate pathway, were up-regulated, leading to the increased production of NADPH, the reducing power for fatty acid biosynthesis. Furthermore, protein and nucleic acid metabolism were down-regulated and some proteins involved in energy metabolism, signal transduction, molecular chaperone and redox homeostasis were up-regulated upon N depletion, which may be the cellular response to the stress produced by the onset of N deficiency. N limitation increased those expressions of the proteins involved in ammonia assimilation but decreased that

Effect of a low-density polyethylene film containing butylated hydroxytoluene on lipid oxidation and protein quality of Sierra fish (Scomberomorus sierra) muscle during frozen storage.

PubMed

Torres-Arreola, Wilfrido; Soto-Valdez, Herlinda; Peralta, Elizabeth; Cardenas-López, José Luis; Ezquerra-Brauer, Josafat Marina

2007-07-25

Fresh sierra fish (Scomberomorus sierra) fillets were packed in low-density polyethylene films with butylated hydroxytoluene (BHT-LDPE) added. Fillets packed in LDPE with no BHT were used as controls (LDPE). The packed fillets were stored at -25 degrees C for 120 days in which the film released 66.5% of the antioxidant. The influence of the antioxidant on lipid and protein quality, lipid oxidation, muscle structure changes, and shear-force resistance was recorded. As compared to LDPE films, fillets packed in BHT-LDPE films showed lower lipid oxidation, thiobarbituric acid values (4.20 +/- 0.52 vs 11.95 +/- 1.06 mg malonaldehyde/kg), peroxide values (7.20 +/- 1.38 vs 15.15 +/- 1.48 meq/kg), and free fatty acids (7.98 +/- 0.43 vs 11.83 +/- 1.26% of oleic acid). Fillets packed in BHT-LDPE films showed less tissue damage and lost less firmness than fillets packed in LDPE. A significant relationship between lipid oxidation and texture was detected (R2 adjusted, 0.70-0.73). BHT-LDPE films may be used not only to prevent lipid oxidation but also to minimize protein damage to prolong the shelf life of sierra fish.

A Neutron View of Proteins in Lipid Bilayers

NASA Astrophysics Data System (ADS)

White, Stephen

2012-02-01

Despite the growing number of atomic-resolution membrane protein structures, direct structural information about proteins in their native membrane environment is scarce. This problem is particularly relevant in the case of the highly-charged S1-S4 voltage- sensing domains responsible for nerve impulses, where interactions with the lipid bilayer are critical for the function of voltage-activated potassium channels. We have used neutron diffraction, solid-state nuclear magnetic resonance spectroscopy, and molecular dynamics simulations to investigate the structure and hydration of bilayer membranes containing S1-S4 voltage-sensing domains. Our results show that voltage sensors adopt transmembrane orientations, cause a modest reshaping of the surrounding lipid bilayer, and that water molecules intimately interact with the protein within the membrane. These structural findings reveal that voltage sensors have evolved to interact with the lipid membrane while keeping the energetic and structural perturbations to a minimum, and that water penetrates into the membrane to hydrate charged residues and shape the transmembrane electric field.

Lipid-based colloidal carriers for peptide and protein delivery – liposomes versus lipid nanoparticles

PubMed Central

Martins, Susana; Sarmento, Bruno; Ferreira, Domingos C; Souto, Eliana B

2007-01-01

This paper highlights the importance of lipid-based colloidal carriers and their pharmaceutical implications in the delivery of peptides and proteins for oral and parenteral administration. There are several examples of biomacromolecules used nowadays in the therapeutics, which are promising candidates to be delivered by means of liposomes and lipid nanoparticles, such as solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC). Several production procedures can be applied to achieve a high association efficiency between the bioactives and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. Generally, this can lead to improved bioavailability, or in case of oral administration a more consistent temporal profile of absorption from the gastrointestinal tract. Advantages and drawbacks of such colloidal carriers are also pointed out. This article describes strategies used for formulation of peptides and proteins, methods used for assessment of association efficiency and practical considerations regarding the toxicological concerns. PMID:18203427

Lipid oxidation by hypochlorous acid: chlorinated lipids in atherosclerosis and myocardial ischemia

PubMed Central

Ford, David A

2011-01-01

Leukocytes, containing myeloperoxidase (MPO), produce the reactive chlorinating species, HOCl, and they have important roles in the pathophysiology of cardiovascular disease. Leukocyte-derived HOCl can target primary amines, alkenes and vinyl ethers of lipids, resulting in chlorinated products. Plasmalogens are vinyl ether-containing phospholipids that are abundant in tissues of the cardiovascular system. The HOCl oxidation products derived from plasmalogens are α-chlorofatty aldehyde and unsaturated molecular species of lysophosphatidylcholine. α-chlorofatty aldehyde is the precursor of both α-chlorofatty alcohol and α-chlorofatty acid. Both α-chlorofatty aldehyde and α-chlorofatty acid accumulate in activated neutrophils and have disparate chemotactic properties. In addition, α-chlorofatty aldehyde increases in activated monocytes, human atherosclerotic lesions and rat infarcted myocardium. This article addresses the pathways for the synthesis of these lipids and their biological targets. PMID:21339854

The effects of abscisic acid, salicylic acid and jasmonic acid on lipid accumulation in two freshwater Chlorella strains.

PubMed

Wu, Guanxun; Gao, Zhengquan; Du, Huanmin; Lin, Bin; Yan, Yuchen; Li, Guoqiang; Guo, Yanyun; Fu, Shenggui; Wei, Gongxiang; Wang, Miaomiao; Cui, Meng; Meng, Chunxiao

2018-03-27

Sustainable renewable energy is being hotly debated globally because the continued use of finite fossil fuels is now widely recognized as being unsustainable. Microalgae potentially offer great opportunities for resolving this challenge. Abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) are involved in regulating many physiological properties and have been widely used in higher plants. To test if phytohormones have an impact on accumulating lipid for microalgae, ABA, JA and SA were used to induce two Chlorella strains in the present study. The results showed 1.0 mg/L ABA, 10 mg/L SA, and 0.5 mg/L JA, led strain C. vulgaris ZF strain to produce a 45%, 42% and 49% lipid content that was 1.8-, 1.7- and 2.0-fold that of controls, respectively. For FACHB 31 (number 31 of the Freshwater Algae Culture Collection at the Institute of Hydrobiology, Chinese Academy of Sciences), the addition of 1.0 mg/L ABA, 10 mg/L SA, and 0.5 mg/L, JA produced 33%, 30% and 38% lipid content, which was 1.8-, 1.6- and 2.1-fold that of controls, respectively. As for lipid productivity, 1.0 mg/L ABA increased the lipid productivity of C. vulgaris ZF strain and FACHB-31 by 123% and 44%; 10 mg/L SA enhanced lipid productivity by 100% and 33%; the best elicitor, 0.5 mg/L JA, augmented lipid productivity by 127% and 75% compared to that of controls, respectively. The results above suggest that the three phytohormones at physiological concentrations play crucial roles in inducing lipid accumulation in Chlorella.

Improved insulin loading in poly(lactic-co-glycolic) acid (PLGA) nanoparticles upon self-assembly with lipids.

PubMed

García-Díaz, María; Foged, Camilla; Nielsen, Hanne Mørck

2015-03-30

Polymeric nanoparticles are widely investigated as drug delivery systems for oral administration. However, the hydrophobic nature of many polymers hampers effective loading of the particles with hydrophilic macromolecules such as insulin. Thus, the aim of this work was to improve the loading of insulin into poly(lactic-co-glycolic) acid (PLGA) nanoparticles by pre-assembly with amphiphilic lipids. Insulin was complexed with soybean phosphatidylcholine or sodium caprate by self-assembly and subsequently loaded into PLGA nanoparticles by using the double emulsion-solvent evaporation technique. The nanoparticles were characterized in terms of size, zeta potential, insulin encapsulation efficiency and loading capacity. Upon pre-assembly with lipids, there was an increased distribution of insulin into the organic phase of the emulsion, eventually resulting in significantly enhanced encapsulation efficiencies (90% as compared to 24% in the absence of lipids). Importantly, the insulin loading capacity was increased up to 20% by using the lipid-insulin complexes. The results further showed that a main fraction of the lipid was incorporated into the nanoparticles and remained associated to the polymer during release studies in buffers, whereas insulin was released in a non-complexed form as a burst of approximately 80% of the loaded insulin. In conclusion, the protein load in PLGA nanoparticles can be significantly increased by employing self-assembled protein-lipid complexes. Copyright © 2014 Elsevier B.V. All rights reserved.

Pulmonary lung surfactant synthetic peptide concentration-dependent modulation of DPPC and POPG acyl chain order in a DPPC:POPG:palmitic acid lipid mixture.

PubMed

Krill, S L; Gupta, S L; Smith, T

1994-05-06

Lung surfactant-associated protein interaction with lipid matrices and the effects on lipid thermotropic phase behavior are areas of active research. Many studies limit the lipids to a single or two-component system. The current investigation utilizes a three-lipid component matrix (DPPC:POPG:palmitic acid) to investigate the impact of a synthetic surfactant protein B fragment (SP-B 53-78 DiACM) on the dynamic surface activity of the lipid admixture as measured by a Wilhelmy surface balance. Also, the modulation of the individual lipid acyl chain order by the peptide within the lipid matrix is studied through the use of thermal perturbation FTIR spectroscopy. The data clearly demonstrate a concentration-dependent effect of the peptide on the surface activity with an improvement in the dynamic surface tension diagram characteristics (decreased surface tension and increased collapse plateau) especially at low, 0.36 M%, peptide concentrations. These effects are diminished upon further addition of the peptide. FTIR spectral data demonstrate that the peptide addition results in a significant increase in the acyl chain order of the DPPC and POPG components as measured by the position of the methylene stretching vibrational bands. DPPC is most sensitive to the peptide presence, while the palmitic acid is least affected. The transition temperatures of the individual lipids are also increased with the addition of the peptide. The presence of POPG in the matrix achieves the surface activity similarly seen with natural lung surfactant relative to a DPPC/palmitic acid lipid matrix alone. Its presence increases the sensitivity of the DPPC acyl chains to the presence of the peptide. These effects on the chain order are most probably related to the increased acyl chain fluidity which POPG imparts to the lipid matrix because of the presence of the cis double bond. The phosphatidylglycerol headgroup also adds a negative charge to the lipid matrix which enhances the peptide-lipid

Changes of lipid and fatty acid absorption induced by high dose of citric acid ester and lecithin emulsifiers.

PubMed

Sadouki, Mohamed; Bouchoucha, Michel

2014-09-01

To describe the effect of two food emulsifiers, lecithin (E322) and citric acid esters of mono-and diglycerides of fatty acids (E472c), on the intestinal absorption of lipids. The experiment was conducted on 24 male Wistar rats randomly assigned in three groups. For two groups of six rats, 30% of the lipid intake was replaced with lecithin (L) or citric acid ester of mono and diglycerides, (E); the remaining 12 rats were the control group (C). Diet and fecal fat analysis was used to determine the apparent lipid absorption (ALA) and fatty acids. ALA was significantly lower in the group E than in the groups C and L (p < 0.001). ALA of long saturated chain fatty acids decreased while the length of the carbon chains increased, and this decrease was higher in the group E. E472c emulsifier decreased the intestinal absorption of lipids.

Quantifying lipid changes in various membrane compartments using lipid binding protein domains.

PubMed

Várnai, Péter; Gulyás, Gergő; Tóth, Dániel J; Sohn, Mira; Sengupta, Nivedita; Balla, Tamas

2017-06-01

One of the largest challenges in cell biology is to map the lipid composition of the membranes of various organelles and define the exact location of processes that control the synthesis and distribution of lipids between cellular compartments. The critical role of phosphoinositides, low-abundant lipids with rapid metabolism and exceptional regulatory importance in the control of almost all aspects of cellular functions created the need for tools to visualize their localizations and dynamics at the single cell level. However, there is also an increasing need for methods to determine the cellular distribution of other lipids regulatory or structural, such as diacylglycerol, phosphatidic acid, or other phospholipids and cholesterol. This review will summarize recent advances in this research field focusing on the means by which changes can be described in more quantitative terms. Published by Elsevier Ltd.

Length and sequence dependence in the association of Huntingtin protein with lipid membranes

NASA Astrophysics Data System (ADS)

Jawahery, Sudi; Nagarajan, Anu; Matysiak, Silvina

2013-03-01

There is a fundamental gap in our understanding of how aggregates of mutant Huntingtin protein (htt) with overextended polyglutamine (polyQ) sequences gain the toxic properties that cause Huntington's disease (HD). Experimental studies have shown that the most important step associated with toxicity is the binding of mutant htt aggregates to lipid membranes. Studies have also shown that flanking amino acid sequences around the polyQ sequence directly affect interactions with the lipid bilayer, and that polyQ sequences of greater than 35 glutamine repeats in htt are a characteristic of HD. The key steps that determine how flanking sequences and polyQ length affect the structure of lipid bilayers remain unknown. In this study, we use atomistic molecular dynamics simulations to study the interactions between lipid membranes of varying compositions and polyQ peptides of varying lengths and flanking sequences. We find that overextended polyQ interactions do cause deformation in model membranes, and that the flanking sequences do play a role in intensifying this deformation by altering the shape of the affected regions.

Characterization of the lipid and protein organization in HBsAg viral particles by steady-state and time-resolved fluorescence spectroscopy.

PubMed

Greiner, Vanille J; Egelé, Caroline; Oncul, Sule; Ronzon, Frédéric; Manin, Catherine; Klymchenko, Andrey; Mély, Yves

2010-08-01

Hepatitis B surface antigen (HBsAg) particles, produced in the yeast Hansenula polymorpha, are 20 nm particles, composed of S surface viral proteins and host-derived lipids. Since the detailed structure of these particles is still missing, we further characterized them by fluorescence techniques. Fluorescence correlation spectroscopy indicated that the particles are mainly monomeric, with about 70 S proteins per particle. The S proteins were characterized through the intrinsic fluorescence of their thirteen Trp residues. Fluorescence quenching and time-resolved fluorescence experiments suggest the presence of both low emissive embedded Trp residues and more emissive Trp residues at the surface of the HBsAg particles. The low emission of the embedded Trp residues is consistent with their close proximity in alpha-helices. Furthermore, S proteins exhibit restricted movement, as expected from their tight association with lipids. The lipid organization of the particles was studied using viscosity-sensitive DPH-based probes and environment sensitive 3-hydroxyflavone probes, and compared to lipid vesicles and low density lipoproteins (LDLs), taken as models. Like LDLs, the HBsAg particles were found to be composed of an ordered rigid lipid interface, probably organized as a phospholipid monolayer, and a more hydrophobic and fluid inner core, likely composed of triglycerides and free fatty acids. However, the lipid core of HBsAg particles was substantially more polar than the LDL one, probably due to its larger content in proteins and its lower content in sterols. Based on our data, we propose a structural model for HBsAg particles where the S proteins deeply penetrate into the lipid core. Copyright 2010 Elsevier Masson SAS. All rights reserved.

Human alpha beta hydrolase domain containing protein 11 and its yeast homolog are lipid hydrolases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arya, Madhuri; Srinivasan, Malathi; Rajasekharan, Ram

Mammalian alpha/beta hydrolase domain (ABHD) family of proteins have emerged as key regulators of lipid metabolism and are found to be associated with human diseases. Human α/β-hydrolase domain containing protein 11 (ABHD11) has recently been predicted as a potential biomarker for human lung adenocarcinoma. In silico analyses of the ABHD11 protein sequence revealed the presence of a conserved lipase motif GXSXG. However, the role of ABHD11 in lipid metabolism is not known. To understand the biological function of ABHD11, we heterologously expressed the human ABHD11 in budding yeast, Saccharomyces cerevisiae. In vivo [{sup 14}C]acetate labeling of cellular lipids in yeast cellsmore » overexpressing ABHD11 showed a decrease in triacylglycerol content. Overexpression of ABHD11 also alters the molecular species of triacylglycerol in yeast. Similar activity was observed in its yeast homolog, Ygr031w. The role of the conserved lipase motif in the hydrolase activity was proven by the mutation of all conserved amino acid residues of GXSXG motif. Collectively, our results demonstrate that human ABHD11 and its yeast homolog YGR031W have a pivotal role in the lipid metabolism. - Highlights: • Overexpression of ABHD11 protein and its yeast homolog Ygr031w cause a reduction in triacylglycerol levels in yeast. • The reduction in triacylglycerol is due to the presence of lipase motif GXSXG. • Overexpression of ABHD11 and Ygr031w alters the molecular species of triacylglycerol.« less

Structural proteomics: Topology and relative accessibility of plant lipid droplet associated proteins.

PubMed

Jolivet, Pascale; Aymé, Laure; Giuliani, Alexandre; Wien, Frank; Chardot, Thierry; Gohon, Yann

2017-10-03

Lipid droplets are the major stock of lipids in oleaginous plant seeds. Despite their economic importance for oil production and biotechnological issues (biofuels, lubricants and plasticizers), numerous questions about their formation, structure and regulation are still unresolved. To determine water accessible domains of protein coating at lipid droplets surface, a structural proteomic approach has been performed. This technique relies on the millisecond timescale production of hydroxyl radicals by the radiolysis of water using Synchrotron X-ray white beam. Thanks to the evolution of mass spectrometry analysis techniques this approach allows the creation of a map of the solvent accessibility for proteins difficult to study by other means. Using these results, a S3 oleosin water accessibility map is proposed. This is the first time that such a map on an oleosin co-purified with plant lipid droplets and other associated protein is presented. Lipid droplet associated proteins function is linked to stability, structure and probably formation and lipid mobilization of droplets. Structure of these proteins in their native environment, at the interface between bulk water and the lipidic core of these organelles is only based on hydrophobicity plot. Using hydroxyl radical footprinting and proteomics approaches we studied water accessibility of one major protein in these droplets: S3 oleosin of Arabidopsis thaliana seeds. Copyright © 2017 Elsevier B.V. All rights reserved.

A Global Map of Lipid-Binding Proteins and Their Ligandability in Cells.

PubMed

Niphakis, Micah J; Lum, Kenneth M; Cognetta, Armand B; Correia, Bruno E; Ichu, Taka-Aki; Olucha, Jose; Brown, Steven J; Kundu, Soumajit; Piscitelli, Fabiana; Rosen, Hugh; Cravatt, Benjamin F

2015-06-18

Lipids play central roles in physiology and disease, where their structural, metabolic, and signaling functions often arise from interactions with proteins. Here, we describe a set of lipid-based chemical proteomic probes and their global interaction map in mammalian cells. These interactions involve hundreds of proteins from diverse functional classes and frequently occur at sites of drug action. We determine the target profiles for several drugs across the lipid-interaction proteome, revealing that its ligandable content extends far beyond traditionally defined categories of druggable proteins. In further support of this finding, we describe a selective ligand for the lipid-binding protein nucleobindin-1 (NUCB1) and show that this compound perturbs the hydrolytic and oxidative metabolism of endocannabinoids in cells. The described chemical proteomic platform thus provides an integrated path to both discover and pharmacologically characterize a wide range of proteins that participate in lipid pathways in cells. Copyright © 2015 Elsevier Inc. All rights reserved.

Amino acid composition and biological effects of supplementing broad bean and corn proteins with Nigella sativa (black cumin) cake protein.

PubMed

al-Gaby, A M

1998-10-01

The biological effects of supplementing broad bean (Vicia faba) or corn (Zea maize) meal protein with black cumin (Nigella sativa) cake protein as well as their amino acid composition were investigated. The percentage of total protein content of Nigella cake was 22.7%. Lysine is existent in abundant amounts in faba meal protein, while leucine is the most abundant in corn meal protein (chemical score = 156) and valine is higher in Nagella cake protein. compared with rats fed sole corn or faba meal protein, substitution of 25% of corn or faba meal protein with Nigella cake protein in the diet remarkably raised the growth rate of rats and resulted in significant higher levels of rat total serum lipids and triglycerides. Also, the supplemented diet caused significant increases in serum total protein and its two fractions albumin and globulin and insignificantly increase the activity of serum phosphatases and transaminases within normal ranges. The supplementation did not have any adverse nutritional effects in the levels of lipid fractions in the serum.

Plasma thiobarbituric acid reactive substances (TBARS) in young adults: Obesity increases fasting levels only in men whereas glucose ingestion, and not protein or lipid intake, increases postprandial concentrations regardless of sex and obesity.

PubMed

Montes-Nieto, Rafael; Insenser, María; Murri, Mora; Fernández-Durán, Elena; Ojeda-Ojeda, Miriam; Martínez-García, María Ángeles; Luque-Ramírez, Manuel; Escobar-Morreale, Héctor F

2017-11-01

Oxidative stress and damage participate in the pathophysiology of obesity and its metabolic complications. We studied the influence of sex, obesity, and ingestion of different macronutrients on fasting and postprandial thiobarbituric acid reactive substances (TBARS), which can be considered as an index of lipid peroxidation and oxidative damage. We studied 19 men and 17 women, out of whom nine men and eight women had obesity. We collected blood samples in the fasting state and, on alternate days, following the ingestion of 300 kcal in the form of glucose, lipids, or proteins. Fasting TBARS concentrations correlated with waist circumference and were increased in obese men compared with nonobese men. This increase was not, however, observed in women. TBARS concentrations showed a marked increase following the ingestion of glucose in parallel to the increase in plasma glucose when considering all subjects as a whole, but did not increase after the oral intake of lipids and proteins. Plasma TBARS concentrations are increased in the fasting state only in obese men in association with abdominal adiposity, and increases markedly after the ingestion of glucose, but not after oral intake of lipids and proteins, regardless of sex and obesity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein and lipid damage in maple syrup urine disease patients: l-carnitine effect.

PubMed

Mescka, Caroline Paula; Wayhs, Carlos Alberto Yasin; Vanzin, Camila Simioni; Biancini, Giovana Brondani; Guerreiro, Gilian; Manfredini, Vanusa; Souza, Carolina; Wajner, Moacir; Dutra-Filho, Carlos Severo; Vargas, Carmen Regla

2013-02-01

Maple syrup urine disease (MSUD) is an inborn error of metabolism biochemically characterized by elevated levels of the branched chain amino acids (BCAA) leucine, isoleucine, valine and the corresponding branched-chain α-keto acids. This disorder is clinically characterized by ketoacidosis, seizures, coma, psychomotor delay and mental retardation whose pathophysiology is not completely understood. Recent studies have shown that oxidative stress may be involved in neuropathology of MSUD. l-Carnitine (l-Car) plays a central role in the cellular energy metabolism because it transports long-chain fatty acids for oxidation and ATP generation. In recent years many studies have demonstrated the antioxidant role of this compound. In this work, we investigated the effect of BCAA-restricted diet supplemented or not with l-Car on lipid peroxidation and in protein oxidation in MSUD patients. We found a significant increase of malondialdehyde and of carbonyl content in plasma of MSUD patients under BCAA-restricted diet compared to controls. Furthermore, patients under BCAA-restricted diet plus l-Car supplementation presented a marked reduction of malondialdehyde content in relation to controls, reducing the lipid peroxidation. In addition, free l-Car concentrations were negatively correlated with malondialdehyde levels. Our data show that l-Car may have an antioxidant effect, protecting against the lipid peroxidation and this could represent an additional therapeutic approach to the patients affected by MSUD. Copyright © 2012 ISDN. Published by Elsevier Ltd. All rights reserved.

Effect of DOPE and cholesterol on the protein adsorption onto lipid nanoparticles

NASA Astrophysics Data System (ADS)

Caracciolo, Giulio; Pozzi, Daniela; Capriotti, Anna Laura; Cavaliere, Chiara; Laganà, Aldo

2013-03-01

Upon administration, nanoparticles (NPs) are exposed to biological fluids from which they adsorb proteins and other biomolecules to form a "protein corona". NP-protein interactions are still poorly understood and quantitative studies to characterize them remain scarce. Here, we have investigated the effect of neutral dioleoylphosphatidylethanolamine (DOPE) and cholesterol on the adsorption of human plasma proteins onto the surface of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)-based cationic liposomes of 100 nm in diameter. Quantitative analysis of the protein corona revealed that replacing cationic DOTAP lipids with neutral lipids, being indifferently DOPE or cholesterol, reduces the affinity of fibrinogen, prothrombin, vitamin K, and vitronectin for the lipid surface. On the other side, DOPE specifically promotes the adsorption of apolipoproteins and serum albumin, while cholesterol induces the preferential binding of immunoglobulins and complement proteins. The results of this study will help to explain why NPs of different lipid compositions have a dramatic difference in their in vivo transfection efficiency and will be useful for design of lipid NPs with optimal circulation profiles.

Unusual heme iron-lipid acyl chain coordination in Escherichia coli flavohemoglobin.

PubMed

D'Angelo, Paola; Lucarelli, Debora; della Longa, Stefano; Benfatto, Maurizio; Hazemann, Jean Louis; Feis, Alessandro; Smulevich, Giulietta; Ilari, Andrea; Bonamore, Alessandra; Boffi, Alberto

2004-06-01

Escherichia coli flavohemoglobin is endowed with the notable property of binding specifically unsaturated and/or cyclopropanated fatty acids both as free acids or incorporated into a phospholipid molecule. Unsaturated or cyclopropanated fatty acid binding to the ferric heme results in a spectral change observed in the visible absorption, resonance Raman, extended x-ray absorption fine spectroscopy (EXAFS), and x-ray absorption near edge spectroscopy (XANES) spectra. Resonance Raman spectra, measured on the flavohemoglobin heme domain, demonstrate that the lipid (linoleic acid or total lipid extracts)-induced spectral signals correspond to a transition from a five-coordinated (typical of the ligand-free protein) to a hexacoordinated, high spin heme iron. EXAFS and XANES measurements have been carried out both on the lipid-free and on the lipid-bound protein to assign the nature of ligand in the sixth coordination position of the ferric heme iron. EXAFS data analysis is consistent with the presence of a couple of atoms in the sixth coordination position at 2.7 A in the lipid-bound derivative (bonding interaction), whereas a contribution at 3.54 A (nonbonding interaction) can be singled out in the lipid-free protein. This last contribution is assigned to the CD1 carbon atoms of the distal LeuE11, in full agreement with crystallographic data on the lipid-free protein at 1.6 A resolution obtained in the present work. Thus, the contributions at 2.7 A distance from the heme iron are assigned to a couple of carbon atoms of the lipid acyl chain, possibly corresponding to the unsaturated carbons of the linoleic acid.

α-lipoic acid ameliorates n-3 highly-unsaturated fatty acids induced lipid peroxidation via regulating antioxidant defenses in grass carp (Ctenopharyngodon idellus).

PubMed

Shi, Xiao-Chen; Jin, Ai; Sun, Jian; Yang, Zhou; Tian, Jing-Jing; Ji, Hong; Yu, Hai-Bo; Li, Yang; Zhou, Ji-Shu; Du, Zhen-Yu; Chen, Li-Qiao

2017-08-01

This study evaluated the protective effect of α-lipoic acid (LA) on n-3 highly unsaturated fatty acids (HUFAs)-induced lipid peroxidation in grass carp. The result indicated that diets with n-3 HUFAs increased the production of malondialdehyde (MDA) (P < 0.05), thereby inducing lipid peroxidation in liver and muscle of grass carp. Meanwhile, compared with control group, the hepatosomatic index (HSI) and kidney index (KI) of grass carp were markedly increased in n-3 HUFAs-only group. However, diets with LA remarkably inhibited the n-3 HUFAs-induced increase of HSI, KI, and MDA level in serum, liver and muscle (P < 0.05). Interestingly, LA also significantly elevated the ratio of total n-3 HUFAs in fatty acid composition of muscle and liver (P < 0.05). Furthermore, LA significantly promoted the activity of antioxidant enzymes in serum, muscle and liver of grass carp (P < 0.05), including superoxide dismutase (SOD), catalase (CAT), and glutathione s-transferase (GST). The further results showed that LA significantly elevated mRNA expression of antioxidant enzymes with promoting the mRNA expression of NF-E2-related nuclear factor 2 (Nrf2) and decreasing Kelch-like-ECH-associated protein 1 (Keap1) mRNA level. From the above, these results suggested that LA could attenuate n-3 HUFAs-induced lipid peroxidation, remit the toxicity of the lipid peroxidant, and protect n-3 HUFAs against lipid peroxidation to promote its deposition in fish, likely strengthening the activity of antioxidant enzymes through regulating mRNA expressions of antioxidant enzyme genes via mediating Nrf2-Keap1 signaling pathways. Copyright © 2017 Elsevier Ltd. All rights reserved.

Lysosomal degradation of membrane lipids.

PubMed

Kolter, Thomas; Sandhoff, Konrad

2010-05-03

The constitutive degradation of membrane components takes place in the acidic compartments of a cell, the endosomes and lysosomes. Sites of lipid degradation are intralysosomal membranes that are formed in endosomes, where the lipid composition is adjusted for degradation. Cholesterol is sorted out of the inner membranes, their content in bis(monoacylglycero)phosphate increases, and, most likely, sphingomyelin is degraded to ceramide. Together with endosomal and lysosomal lipid-binding proteins, the Niemann-Pick disease, type C2-protein, the GM2-activator, and the saposins sap-A, -B, -C, and -D, a suitable membrane lipid composition is required for degradation of complex lipids by hydrolytic enzymes. Copyright 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Effect of acetic acid on lipid accumulation by glucose-fed activated sludge cultures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mondala, Andro; Hernandez, Rafael; French, Todd

2012-01-01

The effect of acetic acid, a lignocellulose hydrolysis by-product, on lipid accumulation by activated sludge cultures grown on glucose was investigated. This was done to assess the possible application of lignocellulose as low-cost and renewable fermentation substrates for biofuel feedstock production. Results: Biomass yield was reduced by around 54% at a 2 g L -1 acetic acid dosage but was increased by around 18% at 10 g L -1 acetic acid dosage relative to the control run. The final gravimetric lipid contents at 2 and 10 g L -1 acetic acid levels were 12.5 + 0.7% and 8.8 + 3.2%more » w/w, respectively, which were lower than the control (17.8 + 2.8% w/w). However, biodiesel yields from activated sludge grown with acetic acid (5.6 + 0.6% w/w for 2 g L -1 acetic acid and 4.2 + 3.0% w/w for 10 g L -1 acetic acid) were higher than in raw activated sludge (1-2% w/w). The fatty acid profiles of the accumulated lipids were similar with conventional plant oil biodiesel feedstocks. Conclusions: Acetic acid enhanced biomass production by activated sludge at high levels but reduced lipid production. Further studies are needed to enhance acetic acid utilization by activated sludge microorganisms for lipid biosynthesis.« less

Deposition of lipid, protein, and secretory phospholipase A2 on hydrophilic contact lenses.

PubMed

Mochizuki, Hiroshi; Yamada, Masakazu; Hatou, Shin; Kawashima, Motoko; Hata, Seiichiro

2008-01-01

Recent studies have shown that low tear phospholipid levels are associated with tear film instability in hydrophilic contact lens wearers. The concentration of secretory phospholipase A2 (sPLA2), the enzyme that hydrolyzes phospholipids, in tears is known to exceed the levels found in serum by four orders of magnitude. This study was performed to determine the levels of sPLA2 from the deposition on two different frequent-replacement contact lens materials. Polymacon and etafilcon A contact lenses worn for 2 weeks by 16 experienced contact lens wearers were used for the analysis. Total lipids were determined by the sulfo-phospho-vanillin reaction. Phospholipids in lipid extracts were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Total protein was measured by bicinchoninic acid analysis. Double-antibody sandwich enzyme-linked immunosorbent assay was used to determine sPLA2 concentrations. Total lipid deposition was found to be greater in the polymacon group (66.3+/-16.3 microg/lens) than in the etafilcon A group, although phospholipids were not detected in either group. The etafilcon A group had greater deposition of protein (3.7+/-0.7 mg/lens) than the polymacon group had. The etafilcon A group deposited statistically significantly more group IIa sPLA2 (1.1+/-0.3 microg/lens) than the polymacon group (0.07+/-0.04 microg/lens) did (P<0.001). There was a significant difference in the lipid and protein deposition profiles in the two lenses tested. A significant amount of sPLA2 in the deposition on contact lenses may play a role in tear film instability in hydrophilic contact lens wearers.

Regulation of Lipid Synthesis in Soybeans by Two Benzoic Acid Herbicides 1

PubMed Central

Muslih, Raad K.; Linscott, Dean L.

1977-01-01

The effects of 3-nitro-2,5-dichlorobenzoic acid (dinoben) and 3-amino-2,4-dichlorobenzoic acid (chloramben) on lipid formation and on the incorporation of various substrates into lipids by intact seeds and subcellular fractions of germinating soybean (Glycine max [L.] Merr. `Amsoy') were studied. Dinoben (20 μg/ml) inhibited synthesis of total lipids 67%, neutral lipids 73%, glycolipids 51%, and phospholipids 39% in germinating seeds. When polar lipids were analyzed further, inhibition of individual lipid classes was also observed. Chloramben (20 μg/ml) stimulated total lipid synthesis 25%. With the exception of the mitochondrial fraction where malonate thiokinase was absent, dinoben inhibited up to 99% the incorporation of acetate and malonate into lipids, but did not inhibit acetyl-CoA and malonyl-CoA incorporation. Chloramben stimulated the incorporation of all substrates tested into lipids by all fractions except the mitochondrial fraction when malonate was the substrate. When dinoben and chloramben were used in combinations, chloramben did not reverse the inhibitory effect of dinoben. It is concluded that the dinoben inhibitory effect is specific and is associated with the acetate and malonate thiokinase systems. The chloramben effect is stimulatory to either acetyl-CoA carboxylase or fatty acid synthetase or both. PMID:16660173

[Fatty acids composition of cellular lipids of the collected and newly isolated Pseudomonas lupini strains].

PubMed

Hvozdiak, R I; Dankevych, L A; Votselko, S K; Holubets', O V

2005-01-01

Fatty acid composition of cellular lipids of 23 Pseudomonas lupini strains (Beltjukova et Koroljova 1968) has been investigated. Cellular fatty acids which contained from C10 to C19 carbon atoms have been identified. Basic fatty acid of those Pseudomonas cells are hexadecanoic, hexadecenoic and octadecanoic acids. The 3-hydroxydecanoic (C10:0 3OH), 3-hydroxydodecanoic (C12:0 3OH), 2-hydroxydodecanoic (C12:0 2OH) and cyclopropane fatty acids which contain 17 and 19 carbon atoms have been detected in cellular lipids. The cellular fatty acids spectra of 22 P. lupini strains are similar to cellular fatty acids spectrum of the type strain Pseudomonas syringae pv. syringae 8511. Pathogenic isolate 2, which fatty acid content of cell lipids significantly differ from lipids of cell fatty acids from P. lupini strains and cell lipids of fatty acids of typical strains Pseudomonas syringae pv. syringae 8511 and Pseudomonas savastanoi pv. phaseolicola 9066 is the exception.

Additive effects of dexamethasone and palmitate on hepatic lipid accumulation and secretion.

PubMed

Harasim-Symbor, Ewa; Konstantynowicz-Nowicka, Karolina; Chabowski, Adrian

2016-11-01

Synthetic and natural glucocorticoids are able to highly modify liver lipid metabolism, which is possibly associated with nonalcoholic fatty liver disease development. We have assessed the changes in lipid and sphingolipid contents in hepatocytes, lipid composition and saturation status as well as the expression of proteins involved in fatty acid transport after both dexamethasone and palmitate treatments. The experiments were conducted on primary rat hepatocytes, incubated with dexamethasone and/or palmitic acid during short (16 h) and prolonged (40 h) exposure. Intracellular and extracellular lipid and sphingolipid contents were assessed by gas liquid chromatography and high-performance liquid chromatography, respectively. The expression of selected proteins was estimated by Western blotting. Short and prolonged exposure to dexamethasone combined with palmitic acid resulted in increased expression of fatty acid transporters, which was subsequently reflected by excessive intracellular accumulation of triacylglycerols and ceramide. The expression of microsomal transfer protein and cassette transporter was also significantly increased after dexamethasone and palmitate treatment, which was in accordance with elevated extracellular lipid and sphingolipid contents. Our data showed additive effects of dexamethasone and palmitate on protein-dependent fatty acid uptake in primary hepatocytes, resulting in the increased accumulation of triacylglycerols and sphingolipids. Moreover, the combined treatment altered fatty acid composition and diminished triacylglycerols desaturation index. Importantly, we observed that additive effects on both increased microsomal transport protein expression as well as elevated export of triacylglycerols, which may be relevant as a liver protective mechanism. © 2016 Society for Endocrinology.

Identification of furan fatty acids in the lipids of common carp (Cyprinus carpio L.).

PubMed

Chvalová, Daniela; Špička, Jiří

2016-06-01

Fatty acid (FA) composition was analyzed in muscle and gonad tissues of marketed common carp (Cyprinus carpio). The extracted lipids were separated into four fractions: polar lipids (PL), diacylglycerols, free fatty acids and triacylglycerols (TAG) using thin layer chromatography. FA content within the lipid fractions was determined by gas chromatography with flame ionization detector (GC/FID). The muscle lipids consisted primarily of TAG (96.9% of total FA), while PL were the major component of both male (67.6%) and female gonad (58.6%) lipids. Polyunsaturated fatty acids predominated in PL of all tissues (52.2-55.8% of total FA); monounsaturated fatty acids were the most abundant FA group in TAG of muscle (51.8%) and female gonads (47.8%) whereas high proportion of furan fatty acids (F-acids) (38.2%) was detected in TAG of male gonads. Eight F-acids were identified by gas chromatography-mass spectrometry (GC/MS) in male gonad samples, including less common 12,15-epoxy-13,14-dimethylnonadeca-12,14-dienoic acid with even-numbered alkyl moiety. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rice protein improves oxidative stress by regulating glutathione metabolism and attenuating oxidative damage to lipids and proteins in rats.

PubMed

Yang, Lin; Chen, Jia-Hou; Xu, Tong; Zhou, Ai-Shen; Yang, Hong-Kun

2012-10-05

To evaluate the effects of rice protein (RP) on glutathione metabolism and oxidative damage. Seven-week-old male Wistar rats were fed diets containing casein and RP without cholesterol for 3weeks. Plasma and liver lipid levels, hepatic accumulation of total glutathione (T-GSH), oxidized glutathione (GSSG), reduced glutathione (GSH), malondialdehyde (MDA) and protein carbonyl (PCO) were measured. In the liver, the total antioxidative capacity (T-AOC), mRNA levels of glutamate cysteine ligase catalytic subunit (GCLC) and glutamate cysteine ligase modulatory subunit (GCLM), and the activities of hepatic catalase (CAT), total superoxide dismutase (T-SOD), γ-glutamylcysteine synthetase (γ-GCS), glutathione S-transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GSHPx) were also measured. T-AOC, GCLC and GCLM mRNA levels, antioxidative enzyme activities (T-SOD and CAT) and glutathione metabolism related enzyme activities (γ-GCS, GST, GR and GSHPx) were effectively stimulated by RP feeding compared to casein, and RP significantly reduced the hepatic accumulation of MDA and PCO in rats. These results indicate that lipid-lowering activity was induced by RP feeding. The present study demonstrates that RP improves oxidative stress primarily through enzymatic and non-enzymatic antioxidative defense mechanisms, reflected by enhancing the antioxidative status and attenuating the oxidative damage to lipids and proteins. These results suggest that RP can prevent hyperlipidemia in part through modifying glutathione metabolism, and sulfur amino acids may be the main modulator of this antioxidative mechanism. Copyright © 2012 Elsevier Inc. All rights reserved.

Lower weight gain and hepatic lipid content in hamsters fed high fat diets supplemented with white rice protein, brown rice protein, soy protein, and their hydrolysates.

PubMed

Zhang, Huijuan; Bartley, Glenn E; Mitchell, Cheryl R; Zhang, Hui; Yokoyama, Wallace

2011-10-26

The physiological effects of the hydrolysates of white rice protein (WRP), brown rice protein (BRP), and soy protein (SP) hydrolyzed by the food grade enzyme, alcalase2.4 L, were compared to the original protein source. Male Syrian Golden hamsters were fed high-fat diets containing either 20% casein (control) or 20% extracted proteins or their hydrolysates as the protein source for 3 weeks. The brown rice protein hydrolysate (BRPH) diet group reduced weight gain 76% compared with the control. Animals fed the BRPH supplemented diet also had lower final body weight, liver weight, very low density lipoprotein cholesterol (VLDL-C), and liver cholesterol, and higher fecal fat and bile acid excretion than the control. Expression levels of hepatic genes for lipid oxidation, PPARα, ACOX1, and CPT1, were highest for hamsters fed the BRPH supplemented diet. Expression of CYP7A1, the gene regulating bile acid synthesis, was higher in all test groups. Expression of CYP51, a gene coding for an enzyme involved in cholesterol synthesis, was highest in the BRPH diet group. The results suggest that BRPH includes unique peptides that reduce weight gain and hepatic cholesterol synthesis.

Enterocyte fatty acid-binding proteins (FABPs): different functions of liver and intestinal FABPs in the intestine.

PubMed

Gajda, Angela M; Storch, Judith

2015-02-01

Fatty acid-binding proteins (FABP) are highly abundant cytosolic proteins that are expressed in most mammalian tissues. In the intestinal enterocyte, both liver- (LFABP; FABP1) and intestinal FABPs (IFABP; FABP2) are expressed. These proteins display high-affinity binding for long-chain fatty acids (FA) and other hydrophobic ligands; thus, they are believed to be involved with uptake and trafficking of lipids in the intestine. In vitro studies have identified differences in ligand-binding stoichiometry and specificity, and in mechanisms of FA transfer to membranes, and it has been hypothesized that LFABP and IFABP have different functions in the enterocyte. Studies directly comparing LFABP- and IFABP-null mice have revealed markedly different phenotypes, indicating that these proteins indeed have different functions in intestinal lipid metabolism and whole body energy homeostasis. In this review, we discuss the evolving knowledge of the functions of LFABP and IFABP in the intestinal enterocyte. Copyright © 2014 Elsevier Ltd. All rights reserved.

Five Decades with Polyunsaturated Fatty Acids: Chemical Synthesis, Enzymatic Formation, Lipid Peroxidation and Its Biological Effects

PubMed Central

Catalá, Angel

2013-01-01

I have been involved in research on polyunsaturated fatty acids since 1964 and this review is intended to cover some of the most important aspects of this work. Polyunsaturated fatty acids have followed me during my whole scientific career and I have published a number of studies concerned with different aspects of them such as chemical synthesis, enzymatic formation, metabolism, transport, physical, chemical, and catalytic properties of a reconstructed desaturase system in liposomes, lipid peroxidation, and their effects. The first project I became involved in was the organic synthesis of [1-14C] eicosa-11,14-dienoic acid, with the aim of demonstrating the participation of that compound as a possible intermediary in the biosynthesis of arachidonic acid “in vivo.” From 1966 to 1982, I was involved in several projects that study the metabolism of polyunsaturated fatty acids. In the eighties, we studied fatty acid binding protein. From 1990 up to now, our laboratory has been interested in the lipid peroxidation of biological membranes from various tissues and different species as well as liposomes prepared with phospholipids rich in PUFAs. We tested the effect of many antioxidants such as alpha tocopherol, vitamin A, melatonin and its structural analogues, and conjugated linoleic acid, among others. PMID:24490074

Extended synaptotagmins are Ca2+-dependent lipid transfer proteins at membrane contact sites.

PubMed

Yu, Haijia; Liu, Yinghui; Gulbranson, Daniel R; Paine, Alex; Rathore, Shailendra S; Shen, Jingshi

2016-04-19

Organelles are in constant communication with each other through exchange of proteins (mediated by trafficking vesicles) and lipids [mediated by both trafficking vesicles and lipid transfer proteins (LTPs)]. It has long been known that vesicle trafficking can be tightly regulated by the second messenger Ca(2+), allowing membrane protein transport to be adjusted according to physiological demands. However, it remains unclear whether LTP-mediated lipid transport can also be regulated by Ca(2+) In this work, we show that extended synaptotagmins (E-Syts), poorly understood membrane proteins at endoplasmic reticulum-plasma membrane contact sites, are Ca(2+)-dependent LTPs. Using both recombinant and endogenous mammalian proteins, we discovered that E-Syts transfer glycerophospholipids between membrane bilayers in the presence of Ca(2+) E-Syts use their lipid-accommodating synaptotagmin-like mitochondrial lipid binding protein (SMP) domains to transfer lipids. However, the SMP domains themselves cannot transport lipids unless the two membranes are tightly tethered by Ca(2+)-bound C2 domains. Strikingly, the Ca(2+)-regulated lipid transfer activity of E-Syts was fully recapitulated when the SMP domain was fused to the cytosolic domain of synaptotagmin-1, the Ca(2+)sensor in synaptic vesicle fusion, indicating that a common mechanism of membrane tethering governs the Ca(2+)regulation of lipid transfer and vesicle fusion. Finally, we showed that microsomal vesicles isolated from mammalian cells contained robust Ca(2+)-dependent lipid transfer activities, which were mediated by E-Syts. These findings established E-Syts as a novel class of LTPs and showed that LTP-mediated lipid trafficking, like vesicular transport, can be subject to tight Ca(2+)regulation.

Engineering Lipid Bilayer Membranes for Protein Studies

PubMed Central

Khan, Muhammad Shuja; Dosoky, Noura Sayed; Williams, John Dalton

2013-01-01

Lipid membranes regulate the flow of nutrients and communication signaling between cells and protect the sub-cellular structures. Recent attempts to fabricate artificial systems using nanostructures that mimic the physiological properties of natural lipid bilayer membranes (LBM) fused with transmembrane proteins have helped demonstrate the importance of temperature, pH, ionic strength, adsorption behavior, conformational reorientation and surface density in cellular membranes which all affect the incorporation of proteins on solid surfaces. Much of this work is performed on artificial templates made of polymer sponges or porous materials based on alumina, mica, and porous silicon (PSi) surfaces. For example, porous silicon materials have high biocompatibility, biodegradability, and photoluminescence, which allow them to be used both as a support structure for lipid bilayers or a template to measure the electrochemical functionality of living cells grown over the surface as in vivo. The variety of these media, coupled with the complex physiological conditions present in living systems, warrant a summary and prospectus detailing which artificial systems provide the most promise for different biological conditions. This study summarizes the use of electrochemical impedance spectroscopy (EIS) data on artificial biological membranes that are closely matched with previously published biological systems using both black lipid membrane and patch clamp techniques. PMID:24185908

Protein Separation by Electrophoretic-Electroosmotic Focusing on Supported Lipid Bilayers

PubMed Central

Liu, Chunming; Monson, Christopher F.; Yang, Tinglu; Pace, Hudson; Cremer, Paul S.

2011-01-01

An electrophoretic-electroosmotic focusing (EEF) method was developed and used to separate membrane-bound proteins and charged lipids based on their charge-to-size ratio from an initially homogeneous mixture. EEF uses opposing electrophoretic and electroosmotic forces to focus and separate proteins and lipids into narrow bands on supported lipid bilayers (SLBs). Membrane-associated species were focused into specific positions within the SLB in a highly repeatable fashion. The steady-state focusing positions of the proteins could be predicted and controlled by tuning experimental conditions, such as buffer pH, ionic strength, electric field and temperature. Careful tuning of the variables should enable one to separate mixtures of membrane proteins with only subtle differences. The EEF technique was found to be an effective way to separate protein mixtures with low initial concentrations, and it overcame diffusive peak broadening to allow four bands to be separated simultaneously within a 380 μm wide isolated supported membrane patch. PMID:21958061

Effect of 2 ppm ozone exposure on rat lung lipid fatty acids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rabinowitz, J.L.; Bassett, D.J.

Based on in vitro studies, the initial damage to lung cells by ozone exposure is believed to result in part from the breakdown of lipid polyunsaturated fatty acids to aldehydes, ozonides, and peroxides. The present study measured lipid breakdown products in lungs isolated from rats pretreated with (1-/sup 14/C)acetate 12 h before exposure for 4 h to either air or 2 ppm ozone. Lipid fatty acid breakdown was indicated by a 112% increase in thiobarbituric acid-reactive substances on ozone exposure and by changes in chemical and radioactive measurements of mono- and dicarboxylic acids formed by treatment of lipid fractions withmore » hydrogen peroxide. Ozone exposure resulted in a 63% increase in recovery of short-chain fatty acids accounted for by increased recoveries of malonic acid by 37%, hexanoic acid by 47%, nonanoic acid by 118%, and azelaic acid by 107%. Recovery of glutaric acid was enhanced 15-fold by ozone exposure. Although decreases in tissue arachidonic acid could not be detected, oleic acid was significantly decreased by 36%. Recovery of radiolabel as short-chain fatty acids was increased by 65% on ozone exposure and was mainly accounted for by enhanced labeling of nonanoic and glutaric acid fractions. The failure to observe significant increases in /sup 14/C recovery in the other fractions suggested ozone-induced breakdown of unlabeled fatty acids. These results demonstrate the cleavage of unsaturated fatty acid double bonds following in vivo exposure of lungs to ozone. Breakdown of arachidonic and oleic acids was specifically identified by increased recoveries of glutaric and nonanoic acids, respectively.« less

A maternal high-fat, high-sucrose diet alters insulin sensitivity and expression of insulin signalling and lipid metabolism genes and proteins in male rat offspring: effect of folic acid supplementation.

PubMed

Cuthbert, Candace E; Foster, Jerome E; Ramdath, D Dan

2017-10-01

A maternal high-fat, high-sucrose (HFS) diet alters offspring glucose and lipid homoeostasis through unknown mechanisms and may be modulated by folic acid. We investigated the effect of a maternal HFS diet on glucose homoeostasis, expression of genes and proteins associated with insulin signalling and lipid metabolism and the effect of prenatal folic acid supplementation (HFS/F) in male rat offspring. Pregnant Sprague-Dawley rats were randomly fed control (CON), HFS or HFS/F diets. Offspring were weaned on CON; at postnatal day 70, fasting plasma insulin and glucose and liver and skeletal muscle gene and protein expression were measured. Treatment effects were assessed by one-way ANOVA. Maternal HFS diet induced higher fasting glucose in offspring v. HFS/F (P=0·027) and down-regulation (P<0·05) of genes coding for v-Akt murine thymoma viral oncogene homolog 2, resistin and v-Raf-1 murine leukaemia viral oncogene homolog 1 (Raf1) in offspring skeletal muscle and acetyl-CoA carboxylase (Acaca), fatty acid synthase and phosphatidylinositol-4,5-biphosphate 3-kinase, catalytic subunit β in offspring liver. Skeletal muscle neuropeptide Y and hepatic Kruppel-like factor 10 were up-regulated in HFS v. CON offspring (P<0·05). Compared with CON, Acaca and Raf1 protein expression levels were significantly lower in HFS offspring. Maternal HFS induced higher homoeostasis model of assessment index of insulin resistance v. CON (P=0·030) and HFS/F was associated with higher insulin (P=0·016) and lower glucose (P=0·025). Maternal HFS diet alters offspring insulin sensitivity and de novo hepatic lipogenesis via altered gene and protein expression, which appears to be potentiated by folate supplementation.

Nordihydroguaiaretic acid protects against high-fat diet-induced fatty liver by activating AMP-activated protein kinase in obese mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung-Su; Kim, Daeyoung; Jo, Keunae

Research highlights: {yields} NDGA decreases high-fat diet-induced body weight gain and adiposity. {yields} NDGA reduces high-fat diet-induced triglyceride accumulation in liver. {yields} NDGA improves lipid storage in vitro through altering lipid regulatory proteins. {yields} Inhibition of lipid storage in vivo and in vitro is mediated by AMPK activation. -- Abstract: Nonalcoholic fatty liver disease, one of the most common causes of chronic liver disease, is strongly associated with metabolic syndrome. Nordihydroguaiaretic acid (NDGA) has been reported to inhibit lipoprotein lipase; however, the effect of NDGA on hepatic lipid metabolism remains unclear. We evaluated body weight, adiposity, liver histology, and hepaticmore » triglyceride content in high-fat diet (HFD)-fed C57BL/6J mice treated with NDGA. In addition, we characterized the underlying mechanism of NDGA's effects in HepG2 hepatocytes by Western blot and RT-PCR analysis. NDGA (100 or 200 mg/kg/day) reduced weight gain, fat pad mass, and hepatic triglyceride accumulation, and improved serum lipid parameters in mice fed a HFD for 8 weeks. NDGA significantly increased AMP-activated protein kinase (AMPK) phosphorylation in the liver and in HepG2 hepatocytes. NDGA downregulated the level of mature SREBP-1 and its target genes (acetyl-CoA carboxylase and fatty acid synthase), but, it upregulated expression of genes involved in fatty acid oxidation, such as peroxisome proliferator-activated receptor (PPAR){alpha}, PPAR{gamma} coactivator-1, carnitine palmitoyl transferase-1, and uncoupling protein-2. The specific AMPK inhibitor compound C attenuated the effects of NDGA on expression of lipid metabolism-related proteins in HepG2 hepatocytes. The beneficial effects of NDGA on HFD-induced hepatic triglyceride accumulation are mediated through AMPK signaling pathways, suggesting a potential target for preventing NAFLD.« less

Nonfeed application of rendered animal proteins for microbial production of eicosapentaenoic acid by the fungus Pythium irregulare.

PubMed

Liang, Yi; Garcia, Rafael A; Piazza, George J; Wen, Zhiyou

2011-11-23

Rendered animal proteins are well suited for animal nutrition applications, but the market is maturing, and there is a need to develop new uses for these products. The objective of this study is to explore the possibility of using animal proteins as a nutrient source for microbial production of omega-3 polyunsaturated fatty acids by the microalga Schizochytrium limacinum and the fungus Pythium irregulare. To be absorbed by the microorganisms, the proteins needed to be hydrolyzed into small peptides and free amino acids. The utility of the protein hydrolysates for microorganisms depended on the hydrolysis method used and the type of microorganism. The enzymatic hydrolysates supported better cell growth performance than the alkali hydrolysates did. P. irregulare displayed better overall growth performance on the experimental hydrolysates compared to S. limacinum. When P. irregulare was grown in medium containing 10 g/L enzymatic hydrolysate derived from meat and bone meal or feather meal, the performance of cell growth, lipid synthesis, and omega-3 fatty acid production was comparable to the that of culture using commercial yeast extract. The fungal biomass derived from the animal proteins had 26-29% lipid, 32-34% protein, 34-39% carbohydrate, and <2% ash content. The results show that it is possible to develop a nonfeed application for rendered animal protein by hydrolysis of the protein and feeding to industrial microorganisms which can produce omega-3 fatty acids for making omega-3-fortified foods or feeds.

Protein-lipid nanohybrids as emerging platforms for drug and gene delivery: Challenges and outcomes.

PubMed

Gaber, Mohamed; Medhat, Waseem; Hany, Mark; Saher, Nourhan; Fang, Jia-You; Elzoghby, Ahmed

2017-05-28

Nanoparticulate drug delivery systems have been long used to deliver a vast range of drugs and bioactives owing to their ability to demonstrate novel physical, chemical, and/or biological properties. An exponential growth has spurred in research and development of these nanocarriers which led to the evolution of a great number of diverse nanosystems including liposomes, nanoemulsions, solid lipid nanoparticles (SLNs), micelles, dendrimers, polymeric nanoparticles (NPs), metallic NPs, and carbon nanotubes. Among them, lipid-based nanocarriers have made the largest progress whether commercially or under development. Despite this progress, these lipid-based nanocarriers suffer from several limitations that led to the development of many protein-coated lipid nanocarriers. To less extent, protein-based nanocarriers suffer from limitations that led to the fabrication of some lipid bilayer enveloping protein nanocarriers. This review discusses in-depth some limitations associated with the lipid-based or protein-based nanocarriers and the fruitful outcomes brought by protein-lipid hybridization. Also discussed are the various hybridization techniques utilized to formulate these protein-lipid nanohybrids and the mechanisms involved in the drug loading process. Copyright © 2017 Elsevier B.V. All rights reserved.

Bioconversion of volatile fatty acids derived from waste activated sludge into lipids by Cryptococcus curvatus.

PubMed

Liu, Jia; Liu, Jia-Nan; Yuan, Ming; Shen, Zi-Heng; Peng, Kai-Ming; Lu, Li-Jun; Huang, Xiang-Feng

2016-07-01

Pure volatile fatty acid (VFA) solution derived from waste activated sludge (WAS) was used to produce microbial lipids as culture medium in this study, which aimed to realize the resource recovery of WAS and provide low-cost feedstock for biodiesel production simultaneously. Cryptococcus curvatus was selected among three oleaginous yeast to produce lipids with VFAs derived from WAS. In batch cultivation, lipid contents increased from 10.2% to 16.8% when carbon to nitrogen ratio increased from about 3.5 to 165 after removal of ammonia nitrogen by struvite precipitation. The lipid content further increased to 39.6% and the biomass increased from 1.56g/L to 4.53g/L after cultivation for five cycles using sequencing batch culture (SBC) strategy. The lipids produced from WAS-derived VFA solution contained nearly 50% of monounsaturated fatty acids, including palmitic acid, heptadecanoic acid, ginkgolic acid, stearic acid, oleic acid, and linoleic acid, which showed the adequacy of biodiesel production. Copyright © 2016 Elsevier Ltd. All rights reserved.

RNA Replicon Delivery via Lipid-Complexed PRINT Protein Particles

PubMed Central

Xu, Jing; Luft, J. Christopher; Yi, Xianwen; Tian, Shaomin; Owens, Gary; Wang, Jin; Johnson, Ashley; Berglund, Peter; Smith, Jonathan; Napier, Mary E.; DeSimone, Joseph M.

2013-01-01

Herein we report the development of a non-viral lipid-complexed PRINT® (particle replication in non-wetting templates) protein particle system (LPP particle) for RNA replicon delivery with a view towards RNA replicon-based vaccination. Cylindrical bovine serum albumin (BSA) particles (diameter (d) 1 µm, height (h) 1 µm) loaded with RNA replicon and stabilized with a fully reversible disulfide cross-linker were fabricated using PRINT technology. Highly efficient delivery of the particles to Vero cells was achieved by complexing particles with a mixture of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) lipids. Our data suggest that: 1) this lipid-complexed protein particle is a promising system for delivery of RNA replicon-based vaccines, and 2) it is necessary to use a degradable cross-linker for successful delivery of RNA replicon via protein-based particles. PMID:23924216

Proteins regulating the biosynthesis and inactivation of neuromodulatory fatty acid amides.

PubMed

Patricelli, M P; Cravatt, B F

2001-01-01

Fatty acid amides (FAAs) represent a growing family of biologically active lipids implicated in a diverse range of cellular and physiological processes. At present, two general types of fatty acid amides, the N-acylethanolamines (NAEs) and the fatty acid primary amides (FAPAs), have been identified as potential physiological neuromodulators/neurotransmitters in mammals. Representative members of these two subfamilies include the endocannabinoid NAE anandamide and the sleep-inducing FAPA oleamide. In this Chapter, molecular mechanisms proposed for the biosynthesis and inactivation of FAAs are critically evaluated, with an emphasis placed on the biochemical and cell biological properties of proteins thought to mediate these processes.

Postprandial lipemia detects the effect of soy protein on cardiovascular disease risk compared with the fasting lipid profile.

PubMed

Santo, Antonio S; Santo, Ariana M; Browne, Richard W; Burton, Harold; Leddy, John J; Horvath, Steven M; Horvath, Peter J

2010-12-01

Studies examining the effect of soy protein on cardiovascular disease (CVD) risk factors have not taken advantage of the postprandial state as an adjunct to the fasting lipid profile. The American Heart Association has acknowledged the efficacy of soy protein in reducing CVD risk factors to be limited. We hypothesized that the postprandial state would be more sensitive to any favorable changes associated with consuming soy protein compared with the fasting lipid profile. Furthermore, the presence of isoflavones in soy would enhance this effect. Thirty sedentary males aged 18-30 years were randomly assigned to milk protein (Milk), isoflavone-poor soy (Soy-), or isoflavone-rich soy (Soy+). Usual diets were supplemented with 25 g/day of protein for 28 days. Serum samples were collected before and after supplementation in a fasted state and postprandially at 30, 60, 120, 240, and 360 min after a high-fat, 1,000 kcal shake. Triacylglycerol (TAG), total cholesterol, non-esterified fatty acids, apolipoproteins B-100 and A-I and glucose concentrations were quantified. Fasting concentrations were not different after any protein supplementation. Postprandial TAG and TAG AUC increased after Soy-consumption supporting the postprandial state as a more sensitive indicator of soy ingestion effects on CVD risk factors compared with the fasting lipid profile. Furthermore, the absence of isoflavones in soy protein may have deleterious consequences on purported cardio-protective effects.

A phosphatidylinositol transfer protein integrates phosphoinositide signaling with lipid droplet metabolism to regulate a developmental program of nutrient stress-induced membrane biogenesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, J.; Pei-Chen Lin, C.; Pathak, M. C.

2016-07-06

Lipid droplet (LD) utilization is an important cellular activity that regulates energy balance and release of lipid second messengers. Because fatty acids exhibit both beneficial and toxic properties, their release from LDs must be controlled. Here we demonstrate that yeast Sfh3, an unusual Sec14-like phosphatidylinositol transfer protein, is an LD-associated protein that inhibits lipid mobilization from these particles. We further document a complex biochemical diversification of LDs during sporulation in which Sfh3 and select other LD proteins redistribute into discrete LD subpopulations. The data show that Sfh3 modulates the efficiency with which a neutral lipid hydrolase-rich LD subclass is consumedmore » during biogenesis of specialized membrane envelopes that package replicated haploid meiotic genomes. These results present novel insights into the interface between phosphoinositide signaling and developmental regulation of LD metabolism and unveil meiosis-specific aspects of Sfh3 (and phosphoinositide) biology that are invisible to contemporary haploid-centric cell biological, proteomic, and functional genomics approaches.« less

A phosphatidylinositol transfer protein integrates phosphoinositide signaling with lipid droplet metabolism to regulate a developmental program of nutrient stress-induced membrane biogenesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Jihui; Lin, Coney Pei-Chen; Pathak, Manish C.

2014-07-11

Lipid droplet (LD) utilization is an important cellular activity that regulates energy balance and release of lipid second messengers. Because fatty acids exhibit both beneficial and toxic properties, their release from LDs must be controlled. Here we demonstrate that yeast Sfh3, an unusual Sec14-like phosphatidylinositol transfer protein, is an LD-associated protein that inhibits lipid mobilization from these particles. We further document a complex biochemical diversification of LDs during sporulation in which Sfh3 and select other LD proteins redistribute into discrete LD subpopulations. The data show that Sfh3 modulates the efficiency with which a neutral lipid hydrolase-rich LD subclass is consumedmore » during biogenesis of specialized membrane envelopes that package replicated haploid meiotic genomes. These results present novel insights into the interface between phosphoinositide signaling and developmental regulation of LD metabolism and unveil meiosis-specific aspects of Sfh3 (and phosphoinositide) biology that are invisible to contemporary haploid-centric cell biological, proteomic, and functional genomics approaches.« less

The unusual lipid binding proteins of parasitic helminths and their potential roles in parasitism and as therapeutic targets.

PubMed

Franchini, Gisela R; Pórfido, Jorge L; Ibáñez Shimabukuro, Marina; Rey Burusco, María F; Bélgamo, Julián A; Smith, Brian O; Kennedy, Malcolm W; Córsico, Betina

2015-02-01

In this review paper we aim at presenting the current knowledge on structural aspects of soluble lipid binding proteins (LBPs) found in parasitic helminths and to discuss their potential role as novel drug targets. Helminth parasites produce and secrete a great variety of LBPs that may participate in the acquisition of nutrients from their host, such as fatty acids and cholesterol. It is also postulated that LBPs might interfere in the regulation of the host׳s immune response by sequestering lipidic intermediates or delivering bioactive lipids. A detailed comprehension of the structure of these proteins, as well as their interactions with ligands and membranes, is important to understand host-parasite relationships that they may mediate. This information could also contribute to determining the role that these proteins may play in the biology of parasitic helminths and how they modulate the immune systems of their hosts, and also towards the development of new therapeutics and prevention of the diseases caused by these highly pathogenic parasites. Copyright © 2014 Elsevier Ltd. All rights reserved.

Interactions of polyphenols with carbohydrates, lipids and proteins.

PubMed

Jakobek, Lidija

2015-05-15

Polyphenols are secondary metabolites in plants, investigated intensively because of their potential positive effects on human health. Their bioavailability and mechanism of positive effects have been studied, in vitro and in vivo. Lately, a high number of studies takes into account the interactions of polyphenols with compounds present in foods, like carbohydrates, proteins or lipids, because these food constituents can have significant effects on the activity of phenolic compounds. This paper reviews the interactions between phenolic compounds and lipids, carbohydrates and proteins and their impact on polyphenol activity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lipids and Fatty Acids of Nudibranch Mollusks: Potential Sources of Bioactive Compounds

PubMed Central

Zhukova, Natalia V.

2014-01-01

The molecular diversity of chemical compounds found in marine animals offers a good chance for the discovery of novel bioactive compounds of unique structures and diverse biological activities. Nudibranch mollusks, which are not protected by a shell and produce chemicals for various ecological uses, including defense against predators, have attracted great interest for their lipid composition. Lipid analysis of eight nudibranch species revealed dominant phospholipids, sterols and monoalkyldiacylglycerols. Among polar lipids, 1-alkenyl-2-acyl glycerophospholipids (plasmalogens) and ceramide-aminoethyl phosphonates were found in the mollusks. The fatty acid compositions of the nudibranchs differed greatly from those of other marine gastropods and exhibited a wide diversity: very long chain fatty acids known as demospongic acids, a series of non-methylene-interrupted fatty acids, including unusual 21:2∆7,13, and an abundance of various odd and branched fatty acids typical of bacteria. Symbiotic bacteria revealed in some species of nudibranchs participate presumably in the production of some compounds serving as a chemical defense for the mollusks. The unique fatty acid composition of the nudibranchs is determined by food supply, inherent biosynthetic activities and intracellular symbiotic microorganisms. The potential of nudibranchs as a source of biologically active lipids and fatty acids is also discussed. PMID:25196731

Altered lipid composition and enhanced lipid production in green microalga by introduction of brassica diacylglycerol acyltransferase 2

PubMed Central

Ahmad, Irshad; Sharma, Anil K.; Daniell, Henry; Kumar, Shashi

2015-01-01

Summary Higher lipid biosynthesis and accumulation are important to achieve economic viability of biofuel production via microalgae. To enhance lipid content, Chlamydomonas reinhardtii was genetically engineered with a key enzyme diacylglycerol acyltransferase (BnDGAT2) from Brassica napus, responsible for neutral lipid biosynthesis. The transformed colonies harbouring aph7 gene, screened on hygromycin-supplemented medium, achieved transformation frequency of ~120 ± 10 colonies/1 × 106 cells. Transgene integration and expression were confirmed by PCR, Southern blots, staining lipid droplets, proteins and spectro-fluorometric analysis of Nile red-stained cells. The neutral lipid is a major class (over 80% of total lipids) and most significant requirement for biodiesel production; this was remarkably higher in the transformed alga than the untransformed control. The levels of saturated fatty acids in the transformed alga decreased to about 7% while unsaturated fatty acids increased proportionately when compared to wild type cells. Polyunsaturated fatty acids, especially α-linolenic acid, an essential omega-3 fatty acid, were enhanced up to 12% in the transformed line. Nile red staining confirmed formation of a large number of lipid globules in the transformed alga. Evaluation of long-term stability and vitality of the transgenic alga revealed that cryopreservation produced significantly higher quantity of lipid than those maintained continuously over 128 generations on solid medium. The overexpression of BnDGAT2 significantly altered the fatty acids profile in the transformed alga. Results of this study offer a valuable strategy of genetic manipulation for enhancing polyunsaturated fatty acids and neutral lipids for biofuel production in algae. PMID:25403771

Dynamics of protein and lipid intake regulation of rainbow trout studied with a wide lipid range of encapsulated diets and self-feeders.

PubMed

Forsman, Antti; Ruohonen, Kari

2009-01-08

Feed intake in fish is examined extensively but there is not much information about the dynamics of regulation i.e. how fish react to different diets, and how these reactions change, over a longer period of time. The present study was designed to evaluate the dynamics of food intake regulation in rainbow trout over a very wide range of dietary protein and lipid levels; from a very low lipid level (5%) to an extremely high level (55%). The study was conducted with three subsequent 40-day blocks of 20 fish and the intake dynamics of the lipid effect were studied by splitting the 40-day experimental period to shorter periods of 10 days. Depending on a diet the rainbow trout were more willing to ingest larger surpluses of both protein and lipid during the periods 0-10, 10-20 and 20-30 days if compared with the anticipated nutritional intake target of rainbow trout. A strong regulatory response against high lipid intake was seen during the last period (days 30-40) leading not only to a decrease in lipid intake but much more drastic decrease in protein intake. Thus, a significant nonlinear interaction between time and dietary protein and lipid was found indicating that the effect of protein and lipid was dynamic.

The human fatty acid-binding protein family: Evolutionary divergences and functions

PubMed Central

2011-01-01

Fatty acid-binding proteins (FABPs) are members of the intracellular lipid-binding protein (iLBP) family and are involved in reversibly binding intracellular hydrophobic ligands and trafficking them throughout cellular compartments, including the peroxisomes, mitochondria, endoplasmic reticulum and nucleus. FABPs are small, structurally conserved cytosolic proteins consisting of a water-filled, interior-binding pocket surrounded by ten anti-parallel beta sheets, forming a beta barrel. At the superior surface, two alpha-helices cap the pocket and are thought to regulate binding. FABPs have broad specificity, including the ability to bind long-chain (C16-C20) fatty acids, eicosanoids, bile salts and peroxisome proliferators. FABPs demonstrate strong evolutionary conservation and are present in a spectrum of species including Drosophila melanogaster, Caenorhabditis elegans, mouse and human. The human genome consists of nine putatively functional protein-coding FABP genes. The most recently identified family member, FABP12, has been less studied. PMID:21504868

Electroporation of the photosynthetic membrane: structural changes in protein and lipid-protein domains.

PubMed Central

Rosemberg, Y; Rotenberg, M; Korenstein, R

1994-01-01

A biological membrane undergoes a reversible permeability increase through structural changes in the lipid domain when exposed to high external electric fields. The present study shows the occurrence of electric field-induced changes in the conductance of the proton channel of the H(+)-ATPase as well as electric field-induced structural changes in the lipid-protein domain of photosystem (PS) II in the photosynthetic membrane. The study was carried out by analyzing the electric field-stimulated delayed luminescence (EPL), which originates from charge recombination in the protein complexes of PS I and II of photosynthetic vesicles. We established that a small fraction of the total electric field-induced conductance change was abolished by N,N'-dicyclohexylcarbodiimide (DCCD), an inhibitor of the H(+)-ATPase. This reversible electric field-induced conductance change has characteristics of a small channel and possesses a lifetime < or = 1 ms. To detect electric field-induced changes in the lipid-protein domains of PS II, we examined the effects of phospholipase A2 (PLA2) on EPL. Higher values of EPL were observed from vesicles that were exposed in the presence of PLA2 to an electroporating electric field than to a nonelectroporating electric field. The effect of the electroporating field was a long-lived one, lasting for a period > or = 2 min. This effect was attributed to long-lived electric field-induced structural changes in the lipid-protein domains of PS II. PMID:7811916

The partial substitution of digestible protein with gelatinized starch as an energy source reduces susceptibility to lipid oxidation in rainbow trout (Oncorhynchus mykiss) and sea bass (Dicentrarchus labrax) muscle.

PubMed

Alvarez, M J; López-Bote, C J; Diez, A; Corraze, G; Arzel, J; Dias, J; Kaushik, S J; Bautista, J M

1999-12-01

We evaluated the influence of dietary gelatinized starch and protein on the fatty acid composition of muscle in rainbow trout and European sea bass and on the susceptibility of flesh to lipid peroxidation. The possibility that flesh peroxidation could be accounted for by lipogenesis and the deposition of fat was also explored. The inclusion of gelatinized starch in the diet of rainbow trout improved growth with respect to that observed in fish fed crude starch (P<.001). This was especially noticeable at the lowest concentration of dietary protein tested (P = .037); suggesting that gelatinized starch may partially replace protein in the production of energy without inducing a negative effect on growth. However, in European sea bass, the gelatinization of starch and dietary protein concentration showed no significant effect on final body weight. The intramuscular neutral lipid concentration of the sea bass was reduced by the gelatinization of dietary starch (P = .034). The highest dietary protein concentration increased the proportion of saturated fatty acids in the neutral (P = .0742) and polar (P = .0033) lipid fractions. The dietary inclusion of high levels of protein in rainbow trout led to a lower concentration of total (n-3) (P = .0457) and (n-6) (P = .0522) fatty acids and a higher concentration of total monounsaturated fatty acids (P = .0006). The inclusion of gelatinized starch led to a lower concentration of (n-3) fatty acids (P = .0034) and a higher concentration of saturated fatty acids (P = .0007). The polar fraction was hardly affected by the same treatment. A significantly lower susceptibility of the dorsal muscle to oxidation was observed in groups of European sea bass fed gelatinized starch (P<.01). A similar trend was observed in rainbow trout, although differences were not significant. The findings suggest that the digestible protein concentration of nutrient-dense diets for rainbow trout and European sea bass can be reduced with a beneficial

Molecular theory of lipid-protein interaction and the Lalpha-HII transition.

PubMed Central

May, S; Ben-Shaul, A

1999-01-01

We present a molecular-level theory for lipid-protein interaction and apply it to the study of lipid-mediated interactions between proteins and the protein-induced transition from the planar bilayer (Lalpha) to the inverse-hexagonal (HII) phase. The proteins are treated as rigid, membrane-spanning, hydrophobic inclusions of different size and shape, e.g., "cylinder-like," "barrel-like," or "vase-like." We assume strong hydrophobic coupling between the protein and its neighbor lipids. This means that, if necessary, the flexible lipid chains surrounding the protein will stretch, compress, and/or tilt to bridge the hydrophobic thickness mismatch between the protein and the unperturbed bilayer. The system free energy is expressed as an integral over local molecular contributions, the latter accounting for interheadgroup repulsion, hydrocarbon-water surface energy, and chain stretching-tilting effects. We show that the molecular interaction constants are intimately related to familiar elastic (continuum) characteristics of the membrane, such as the bending rigidity and spontaneous curvature, as well as to the less familiar tilt modulus. The equilibrium configuration of the membrane is determined by minimizing the free energy functional, subject to boundary conditions dictated by the size, shape, and spatial distribution of inclusions. A similar procedure is used to calculate the free energy and structure of peptide-free and peptide-rich hexagonal phases. Two degrees of freedom are involved in the variational minimization procedure: the local length and local tilt angle of the lipid chains. The inclusion of chain tilt is particularly important for studying noncylindrical (for instance, barrel-like) inclusions and analyzing the structure of the HII lipid phase; e.g., we find that chain tilt relaxation implies strong faceting of the lipid monolayers in the hexagonal phase. Consistent with experiment, we find that only short peptides (large negative mismatch) can induce the

Hepatitis B Virus X Protein Induces Hepatic Steatosis by Enhancing the Expression of Liver Fatty Acid Binding Protein.

PubMed

Wu, Yun-Li; Peng, Xian-E; Zhu, Yi-Bing; Yan, Xiao-Li; Chen, Wan-Nan; Lin, Xu

2016-02-15

Hepatitis B virus (HBV) has been implicated as a potential trigger of hepatic steatosis although molecular mechanisms involved in the pathogenesis of HBV-associated hepatic steatosis still remain elusive. Our prior work has revealed that the expression level of liver fatty acid binding protein 1 (FABP1), a key regulator of hepatic lipid metabolism, was elevated in HBV-producing hepatoma cells. In this study, the effects of HBV X protein (HBx) mediated FABP1 regulation on hepatic steatosis and the underlying mechanism were determined. mRNA and protein levels of FABP1 were measured by quantitative RT-PCR (qPCR) and Western blotting. HBx-mediated FABP1 regulation was evaluated by luciferase assay, coimmunoprecipitation, and chromatin immunoprecipitation. Hepatic lipid accumulation was measured by using Oil-Red-O staining and the triglyceride level. It was found that expression of FABP1 was increased in HBV-producing hepatoma cells, the sera of HBV-infected patients, and the sera and liver tissues of HBV-transgenic mice. Ectopic overexpression of HBx resulted in upregulation of FABP1 in HBx-expressing hepatoma cells, whereas HBx abolishment reduced FABP1 expression. Mechanistically, HBx activated the FABP1 promoter in an HNF3β-, C/EBPα-, and PPARα-dependent manner, in which HBx increased the gene expression of HNF3β and physically interacted with C/EBPα and PPARα. On the other hand, knockdown of FABP1 remarkably blocked lipid accumulation both in long-chain free fatty acids treated HBx-expressing HepG2 cells and in a high-fat diet-fed HBx-transgenic mice. Therefore, FABP1 is a key driver gene in HBx-induced hepatic lipid accumulation via regulation of HNF3β, C/EBPα, and PPARα. FABP1 may represent a novel target for treatment of HBV-associated hepatic steatosis. Accumulating evidence from epidemiological and experimental studies has indicated that chronic HBV infection is associated with hepatic steatosis. However, the molecular mechanism underlying HBV

SH2 Domains Serve as Lipid-Binding Modules for pTyr-Signaling Proteins.

PubMed

Park, Mi-Jeong; Sheng, Ren; Silkov, Antonina; Jung, Da-Jung; Wang, Zhi-Gang; Xin, Yao; Kim, Hyunjin; Thiagarajan-Rosenkranz, Pallavi; Song, Seohyeon; Yoon, Youngdae; Nam, Wonhee; Kim, Ilshin; Kim, Eui; Lee, Dong-Gyu; Chen, Yong; Singaram, Indira; Wang, Li; Jang, Myoung Ho; Hwang, Cheol-Sang; Honig, Barry; Ryu, Sungho; Lorieau, Justin; Kim, You-Me; Cho, Wonhwa

2016-04-07

The Src-homology 2 (SH2) domain is a protein interaction domain that directs myriad phosphotyrosine (pY)-signaling pathways. Genome-wide screening of human SH2 domains reveals that ∼90% of SH2 domains bind plasma membrane lipids and many have high phosphoinositide specificity. They bind lipids using surface cationic patches separate from pY-binding pockets, thus binding lipids and the pY motif independently. The patches form grooves for specific lipid headgroup recognition or flat surfaces for non-specific membrane binding and both types of interaction are important for cellular function and regulation of SH2 domain-containing proteins. Cellular studies with ZAP70 showed that multiple lipids bind its C-terminal SH2 domain in a spatiotemporally specific manner and thereby exert exquisite spatiotemporal control over its protein binding and signaling activities in T cells. Collectively, this study reveals how lipids control SH2 domain-mediated cellular protein-protein interaction networks and suggest a new strategy for therapeutic modulation of pY-signaling pathways. Copyright © 2016 Elsevier Inc. All rights reserved.

Fatty acid binding proteins and the nervous system: Their impact on mental conditions.

PubMed

Matsumata, Miho; Inada, Hitoshi; Osumi, Noriko

2016-01-01

The brain is rich in lipid and fatty molecules. In this review article, we focus on fatty acid binding proteins (Fabps) that bind to fatty acids such as arachidonic acid and docosahexianoic acid and transfer these lipid ligands within the cytoplasm. Among Fabp family molecules, Fabp3, Fabp5, and Fabp7 are specifically localized in neural stem/progenitor cells, neurons and glia in a cell-type specific manner. Quantitative trait locus analysis has revealed that Fabp7 is related with performance of prepulse inhibition (PPI) that is used as an endophenotype of psychiatric diseases such as schizophrenia. Fabp5 and Fabp7 play important roles on neurogenesis and differentially regulate acoustic startle response and PPI. However, other behavior performances including spatial memory, anxiety-like behavior, and diurnal changes in general activity were not different in mice deficient for Fabp7 or Fabp5. Considering the importance of fatty acids in neurogenesis, we would like to emphasize that lipid nutrition and its dynamism via Fabps play significant roles in mental conditions. This might provide a good example of how nutritional environment can affect psychiatric conditions at the molecular level. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Lipid-protein stoichiometries in a crystalline biological membrane: NMR quantitative analysis of the lipid extract of the purple membrane.

PubMed

Corcelli, Angela; Lattanzio, Veronica M T; Mascolo, Giuseppe; Papadia, Paride; Fanizzi, Francesco

2002-01-01

The lipid/protein stoichiometries of a naturally crystalline biological membrane, the purple membrane (PM) of Halobacterium salinarum, have been obtained by a combination of (31)P- and (1)H-NMR analyses of the lipid extract. In total, 10 lipid molecules per retinal were found to be present in the PM lipid extract: 2-3 molecules of phosphatidylglycerophosphate methyl ester (PGP-Me), 3 of glycolipid sulfate, 1 of phosphatidylglycerol, 1 of archaeal glycocardiolipin (GlyC), 2 of squalene plus minor amounts of phosphatidylglycerosulfate (PGS) and bisphosphatidylglycerol (archaeal cardiolipin) (BPG) and a negligible amount of vitamin MK8. The novel data of the present study are necessary to identify the lipids in the electron density map, and to shed light on the structural relationships of the lipid and protein components of the PM.

Cholesterol and Fatty Acids Regulate Dynamic Caveolin Trafficking through the Golgi Complex and between the Cell Surface and Lipid BodiesV⃞

PubMed Central

Pol, Albert; Martin, Sally; Fernández, Manuel A.; Ingelmo-Torres, Mercedes; Ferguson, Charles; Enrich, Carlos; Parton, Robert G.

2005-01-01

Caveolins are a crucial component of plasma membrane (PM) caveolae but have also been localized to intracellular compartments, including the Golgi complex and lipid bodies. Mutant caveolins associated with human disease show aberrant trafficking to the PM and Golgi accumulation. We now show that the Golgi pool of mainly newly synthesized protein is detergent-soluble and predominantly in a monomeric state, in contrast to the surface pool. Caveolin at the PM is not recognized by specific caveolin antibodies unless PM cholesterol is depleted. Exit from the Golgi complex of wild-type caveolin-1 or -3, but not vesicular stomatitis virus-G protein, is modulated by changing cellular cholesterol levels. In contrast, a muscular dystrophy-associated mutant of caveolin-3, Cav3P104L, showed increased accumulation in the Golgi complex upon cholesterol treatment. In addition, we demonstrate that in response to fatty acid treatment caveolin can follow a previously undescribed pathway from the PM to lipid bodies and can move from lipid bodies to the PM in response to removal of fatty acids. The results suggest that cholesterol is a rate-limiting component for caveolin trafficking. Changes in caveolin flux through the exocytic pathway can therefore be an indicator of cellular cholesterol and fatty acid levels. PMID:15689493

Examining protein-lipid interactions in model systems with a new squarylium fluorescent dye.

PubMed

Ioffe, Valeriya M; Gorbenko, Galyna P; Tatarets, Anatoliy L; Patsenker, Leonid D; Terpechnig, Ewald A

2006-07-01

The applicability of newly synthesized squarylium dye Sq to probing the changes in physical characteristics of lipid bilayer on the formation of protein-lipid complexes has been evaluated. Lipid vesicles composed of zwitterionic phospholipid phosphatidylcholine (PC) and its mixtures with positively charged detergent cetyltrimethylammonium bromide (CTAB), anionic phospholipid cardiolipin (CL), and cholesterol (Chol) were employed as lipid component of model membrane systems while protein constituent was represented by lysozyme (Lz). Fluorescence intensity of Sq was found to decrease on Lz association with lipid bilayer. This effect was observed in all kinds of model systems suggesting that Sq is sensitive to modification of lipid bilayer physical properties on hydrophobic protein-lipid interactions. It was found that Sq spectral response to variations in Chol content depends on relative contributions of electrostatic and hydrophobic components of Lz-membrane binding.

Comparative Proteome Analysis between High Lipid-Producing Strain Mucor circinelloides WJ11 and Low Lipid-Producing Strain CBS 277.49.

PubMed

Tang, Xin; Chen, Haiqin; Gu, Zhennan; Zhang, Hao; Chen, Yong Q; Song, Yuanda; Chen, Wei

2017-06-21

Mucor circinelloides is one of few oleaginous fungi that produces a useful oil rich in γ-linolenic acid, but it usually only produces <25% total lipid. Nevertheless, we isolated a new strain WJ11 that can produce up to 36% lipid of cell dry weight. In this study, we have systematically analyzed the global changes in protein levels between the high lipid-producing strain WJ11 and the low lipid-producing strain CBS 277.49 (15%, lipid/cell dry weight) at lipid accumulation phase through comparative proteome analysis. Proteome analysis demonstrated that the branched-chain amino acid and lysine metabolism, glycolytic pathway, and pentose phosphate pathway in WJ11 were up-regulated, while the activities of tricarboxylic acid cycle and branch point enzyme for synthesis of isoprenoids were retarded compared with CBS 277.49. The coordinated regulation at proteome level indicate that more acetyl-CoA and NADPH are provided for fatty acid biosynthesis in WJ11 compared with CBS 277.49.

Patatin-like phospholipase domain–containing protein 3 promotes transfers of essential fatty acids from triglycerides to phospholipids in hepatic lipid droplets

PubMed Central

Mitsche, Matthew A.; Hobbs, Helen H.; Cohen, Jonathan C.

2018-01-01

Fatty liver disease (FLD) is a burgeoning health problem. A missense variant (I148M) in patatin-like phospholipase domain–containing protein 3 (PNPLA3) confers susceptibility to FLD, although the mechanism is not known. To glean first insights into the physiological function of PNPLA3, we performed detailed lipidomic profiling of liver lysates and lipid droplets (LDs) from WT and Pnpla3−/− (KO) mice and from knock-in (ki) mice expressing either the 148M variant (IM-ki mice) or a variant (S47A) that renders the protein catalytically inactive (SA-ki mice). The four strains differed in composition of very-long-chain polyunsaturated fatty acids (vLCPUFA) in hepatic LDs. In the LDs of IM-ki mice, vLCPUFAs were depleted from triglycerides and enriched in phospholipids. Conversely, vLCPUFAs were enriched in triglycerides and depleted from phospholipids in SA-ki and Pnpla3−/− mice. Release of vLCPUFAs from hepatic LDs incubated ex vivo was increased in droplets from IM-ki mice and decreased from droplets isolated from Pnpla3−/− and SA-ki mice relative to those of WT mice. Thus, the physiological role of PNPLA3 appears to be to remodel triglycerides and phospholipids in LDs, perhaps to accommodate changes in LD size in response to feeding. Because SA-ki and IM-ki both cause FLD and yet have opposite effects on the lipidomic profile of LDs, we conclude that the FLD associated with genetic variation in PNPLA3 is not related to the enzyme's role in remodeling LD lipids. PMID:29555681

Neuronal sphingolipidoses: Membrane lipids and sphingolipid activator proteins regulate lysosomal sphingolipid catabolism.

PubMed

Sandhoff, Konrad

2016-11-01

Glycosphingolipids and sphingolipids of cellular plasma membranes (PMs) reach luminal intra-lysosomal vesicles (LVs) for degradation mainly by pathways of endocytosis. After a sorting and maturation process (e.g. degradation of sphingomyelin (SM) and secretion of cholesterol), sphingolipids of the LVs are digested by soluble enzymes with the help of activator (lipid binding and transfer) proteins. Inherited defects of lipid-cleaving enzymes and lipid binding and transfer proteins cause manifold and fatal, often neurodegenerative diseases. The review summarizes recent findings on the regulation of sphingolipid catabolism and cholesterol secretion from the endosomal compartment by lipid modifiers, an essential stimulation by anionic membrane lipids and an inhibition of crucial steps by cholesterol and SM. Reconstitution experiments in the presence of all proteins needed, hydrolase and activator proteins, reveal an up to 10-fold increase of ganglioside catabolism just by the incorporation of anionic lipids into the ganglioside carrying membranes, whereas an additional incorporation of cholesterol inhibits GM2 catabolism substantially. It is suggested that lipid and other low molecular modifiers affect the genotype-phenotype relationship observed in patients with lysosomal diseases. Copyright © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Stability of lipid encapsulated ferulic acid particles

USDA-ARS?s Scientific Manuscript database

Encapsulation of bioactive compounds by a solid lipid matrix provides stability and a mechanism for controlled release in formulated products. Phenolic compounds exhibit antioxidant and antimicrobial activities and have applications as functional food and feed additives. Ferulic acid, a common pheno...

Activation of AMPK by berberine induces hepatic lipid accumulation by upregulation of fatty acid translocase CD36 in mice.

PubMed

Choi, You-Jin; Lee, Kang-Yo; Jung, Seung-Hwan; Kim, Hyung Sik; Shim, Gayong; Kim, Mi-Gyeong; Oh, Yu-Kyoung; Oh, Seon-Hee; Jun, Dae Won; Lee, Byung-Hoon

2017-02-01

Emerging evidence has shown that berberine has a protective effect against metabolic syndrome such as obesity and type II diabetes mellitus by activating AMP-activated protein kinase (AMPK). AMPK induces CD36 trafficking to the sarcolemma for fatty acid uptake and oxidation in contracting muscle. However, little is known about the effects of AMPK on CD36 regulation in the liver. We investigated whether AMPK activation by berberine affects CD36 expression and fatty acid uptake in hepatocytes and whether it is linked to hepatic lipid accumulation. Activation of AMPK by berberine or transduction with adenoviral vectors encoding constitutively active AMPK in HepG2 and mouse primary hepatocytes increased the expression and membrane translocation of CD36, resulting in enhanced fatty acid uptake and lipid accumulation as determined by BODIPY-C16 and Nile red fluorescence, respectively. Activation of AMPK by berberine induced the phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2) and subsequently induced CCAAT/enhancer-binding protein β (C/EBPβ) binding to the C/EBP-response element in the CD36 promoter in hepatocytes. In addition, hepatic CD36 expression and triglyceride levels were increased in normal diet-fed mice treated with berberine, but completely prevented when hepatic CD36 was silenced with adenovirus containing CD36-specific shRNA. Taken together, prolonged activation of AMPK by berberine increased CD36 expression in hepatocytes, resulting in fatty acid uptake via processes linked to hepatocellular lipid accumulation and fatty liver. Copyright © 2016 Elsevier Inc. All rights reserved.

Fatty acids from VLDL lipolysis products induce lipid droplet accumulation in human monocytes

PubMed Central

den Hartigh, Laura J; Connolly-Rohrbach, Jaime E; Fore, Samantha; Huser, Thomas R; Rutledge, John C

2010-01-01

One mechanism by which monocytes become activated postprandially is by exposure to triglyceride (TG)-rich lipoproteins such as very low-density lipoproteins (VLDL). VLDL are hydrolyzed by lipoprotein lipase (LpL) at the blood-endothelial cell interface, releasing free fatty acids. In this study, we examined postprandial monocyte activation in more detail, and found that lipolysis products generated from postprandial VLDL induce the formation of lipid-filled droplets within cultured THP-1 monocytes, characterized by coherent anti-stokes Raman spectroscopy. Organelle-specific stains revealed an association of lipid droplets with the endoplasmic reticulum, confirmed by electron microscopy. Lipid droplet formation was reduced when LpL-released fatty acids were bound by bovine serum albumin, which also reduced cellular inflammation. Furthermore, saturated fatty acids induced more lipid droplet formation in monocytes compared to mono- and polyunsaturated fatty acids. Monocytes treated with postprandial VLDL lipolysis products contained lipid droplets with more intense saturated Raman spectroscopic signals than monocytes treated with fasting VLDL lipolysis products. In addition, we found that human monocytes isolated during the peak postprandial period contain more lipid droplets compared to those from the fasting state, signifying that their development is not limited to cultured cells but also occurs in vivo. In summary, circulating free fatty acids can mediate lipid droplet formation in monocytes and potentially be used as a biomarker to assess an individual’s risk of developing atherosclerotic cardiovascular disease. PMID:20208007

Charge-switching amino acids-based cationic lipids for efficient gene delivery.

PubMed

Zheng, Li-Ting; Yi, Wen-Jing; Liu, Qiang; Su, Rong-Chuan; Zhao, Zhi-Gang

2015-12-15

A series of charge-switching amino acids-based cationic lipids 4a-4e bearing a benzyl ester at the terminus of the acyl chain, but differing in the polar-head group were prepared. The physicochemical properties of these lipids, including size, zeta potential and cellular uptake of the lipoplexes formed from with DNA, as well as the transfection efficiency (TE), were investigated. The results showed that the chemical structure of the cationic head-group clearly affects the physicochemical parameters of the amino acid-based lipids and especially the TE. The selected lipid, 4c gave 2.1 times higher TE than bPEI 25k in the presence of 10% serum in HeLa cells, with little toxicity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bumble bees regulate their intake of essential protein and lipid pollen macronutrients.

PubMed

Vaudo, A D; Stabler, D; Patch, H M; Tooker, J F; Grozinger, C M; Wright, G A

2016-12-15

Bee population declines are linked to the reduction of nutritional resources due to land-use intensification, yet we know little about the specific nutritional needs of many bee species. Pollen provides bees with their primary source of protein and lipids, but nutritional quality varies widely among host-plant species. Therefore, bees might have adapted to assess resource quality and adjust their foraging behavior to balance nutrition from multiple food sources. We tested the ability of two bumble bee species, Bombus terrestris and Bombus impatiens, to regulate protein and lipid intake. We restricted B. terrestris adults to single synthetic diets varying in protein:lipid ratios (P:L). The bees over-ate protein on low-fat diets and over-ate lipid on high-fat diets to reach their targets of lipid and protein, respectively. The bees survived best on a 10:1 P:L diet; the risk of dying increased as a function of dietary lipid when bees ate diets with lipid contents greater than 5:1 P:L. Hypothesizing that the P:L intake target of adult worker bumble bees was between 25:1 and 5:1, we presented workers from both species with unbalanced but complementary paired diets to determine whether they self-select their diet to reach a specific intake target. Bees consumed similar amounts of proteins and lipids in each treatment and averaged a 14:1 P:L for B. terrestris and 12:1 P:L for B. impatiens These results demonstrate that adult worker bumble bees likely select foods that provide them with a specific ratio of P:L. These P:L intake targets could affect pollen foraging in the field and help explain patterns of host-plant species choice by bumble bees. © 2016. Published by The Company of Biologists Ltd.

The effects of fasting in Ramadan. 1. Serum uric acid and lipid concentrations.

PubMed

Gumaa, K A; Mustafa, K Y; Mahmoud, N A; Gader, A M

1978-11-01

1. The changes in serum levels of uric acid and lipids during 1 month of starvation-refeeding were measured in sixteen male volunteers. 2. Uric acid levels increased linearly with the duration of the experiment. The increase was positively correlated with the increase in serum triglycerides but not with cholesterol or phospholipids. 3. Triglycerides increased at a faster rate than uric acid implying that the increase in uric acid was secondary to that of the lipid. 4. It was concluded that the purine and lipid synthetic pathways are linked through a common small-molecular-weight effector rather than through the sharing of a common enzyme.

In vitro evaluation of α-lipoic acid-loaded lipid nanocapsules for topical delivery.

PubMed

Xia, Nan; Liu, Tian; Wang, Qiang; Xia, Qiang; Bian, Xiaoli

2017-09-01

This study aimed at in vitro evaluation of α-lipoic acid-loaded lipid nanocapsules for topical delivery, which was prepared by hot high-pressure homogenisation. Stable particles could be formed and particle size was 148.54 ± 2.31 nm with polydispersity index below 0.15. Encapsulation efficiency and drug loading of α-lipoic acid were 95.23 ± 0.45% and 2.81 ± 0.37%. Antioxidant study showed α-lipoic acid could be protected by lipid nanocapsules without loss of antioxidant activity. Sustained release of α-lipoic acid from lipid nanocapsules was obtained and cumulative release was 62.18 ± 1.51%. In vitro percutaneous study showed the amount of α-lipoic acid distributed in skin was 1.7-fold than permeated. Cytotoxicity assay and antioxidant activity on L929 cells indicated this formulation had low cytotoxicity and ability of protecting cells from oxidative damage within specific concentration. These studies suggested α-lipoic acid-loaded lipid nanocapsules could be potential formulation for topical delivery.

Schistosoma mansoni venom allergen-like protein 4 (SmVAL4) is a novel lipid-binding SCP/TAPS protein that lacks the prototypical CAP motifs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelleher, Alan; Darwiche, Rabih; Rezende, Wanderson C.

2014-08-01

The first structure of an S. mansoni venom allergen-like protein is presented. Schistosomiasis is a parasitic disease that affects over 200 million people. Vaccine candidates have been identified, including Schistosoma mansoni venom allergen-like proteins (SmVALs) from the SCP/TAPS (sperm-coating protein/Tpx/antigen 5/pathogenesis related-1/Sc7) superfamily. The first SmVAL structure, SmVAL4, was refined to a resolution limit of 2.16 Å. SmVAL4 has a unique structure that could not be predicted from homologous structures, with longer loops and an unusual C-terminal extension. SmVAL4 has the characteristic α/β-sandwich and central SCP/TAPS cavity. Furthermore, SmVAL4 has only one of the signature CAP cavity tetrad amino-acid residuesmore » and is missing the histidines that coordinate divalent cations such as Zn{sup 2+} in other SCP/TAPS proteins. SmVAL4 has a cavity between α-helices 1 and 4 that was observed to bind lipids in tablysin-15, suggesting the ability to bind lipids. Subsequently, SmVAL4 was shown to bind cholesterol in vitro. Additionally, SmVAL4 was shown to complement the in vivo sterol-export phenotype of yeast mutants lacking their endogenous CAP proteins. Expression of SmVAL4 in yeast cells lacking endogenous CAP function restores the block in sterol export. These studies suggest an evolutionarily conserved lipid-binding function shared by CAP proteins such as SmVAL4 and yeast CAP proteins such as Pry1.« less

Evidence for a structural role for acid-fast lipids in oocyst walls of Cryptosporidium, Toxoplasma, and Eimeria.

PubMed

Bushkin, G Guy; Motari, Edwin; Carpentieri, Andrea; Dubey, Jitender P; Costello, Catherine E; Robbins, Phillips W; Samuelson, John

2013-09-03

Coccidia are protozoan parasites that cause significant human disease and are of major agricultural importance. Cryptosporidium spp. cause diarrhea in humans and animals, while Toxoplasma causes disseminated infections in fetuses and untreated AIDS patients. Eimeria is a major pathogen of commercial chickens. Oocysts, which are the infectious form of Cryptosporidium and Eimeria and one of two infectious forms of Toxoplasma (the other is tissue cysts in undercooked meat), have a multilayered wall. Recently we showed that the inner layer of the oocyst walls of Toxoplasma and Eimeria is a porous scaffold of fibers of β-1,3-glucan, which are also present in fungal walls but are absent from Cryptosporidium oocyst walls. Here we present evidence for a structural role for lipids in the oocyst walls of Cryptosporidium, Toxoplasma, and Eimeria. Briefly, oocyst walls of each organism label with acid-fast stains that bind to lipids in the walls of mycobacteria. Polyketide synthases similar to those that make mycobacterial wall lipids are abundant in oocysts of Toxoplasma and Eimeria and are predicted in Cryptosporidium. The outer layer of oocyst wall of Eimeria and the entire oocyst wall of Cryptosporidium are dissolved by organic solvents. Oocyst wall lipids are complex mixtures of triglycerides, some of which contain polyhydroxy fatty acyl chains like those present in plant cutin or elongated fatty acyl chains like mycolic acids. We propose a two-layered model of the oocyst wall (glucan and acid-fast lipids) that resembles the two-layered walls of mycobacteria (peptidoglycan and acid-fast lipids) and plants (cellulose and cutin). Oocysts, which are essential for the fecal-oral spread of coccidia, have a wall that is thought responsible for their survival in the environment and for their transit through the stomach and small intestine. While oocyst walls of Toxoplasma and Eimeria are strengthened by a porous scaffold of fibrils of β-1,3-glucan and by proteins cross

Effects of Tannic Acid on Lipid and Protein Oxidation, Color, and Volatiles of Raw and Cooked Chicken Breast Meat during Storage

PubMed Central

Al-Hijazeen, Marwan; Lee, Eun Joo; Mendonca, Aubrey; Ahn, Dong Uk

2016-01-01

The objective of this study was to determine the effect of tannic acid (TA) on the oxidative stability and the quality characteristics of ground chicken breast meat. Five treatments including (1) control (none added), (2) 2.5 ppm TA, (3) 5 ppm TA, (4) 10 ppm TA, and (5) 5 ppm butylated hydroxyanisole (BHA) were added to boneless, skinless ground chicken breast meat, and used for both raw and cooked meat studies. For the raw meat study, the ground chicken breast meat was packaged in oxygen-permeable bags and stored at 4 °C for 7 days. For the cooked study, raw ground meat samples were vacuum-packaged in oxygen-impermeable vacuum bags, cooked in-bag to the internal temperature of 75 °C, re-packaged in oxygen-permeable bags, and then stored. Both raw and cooked meats were analyzed for lipid and protein oxidation, color, and volatiles (cooked meat only) at 0, 3, and 7 days of storage. Raw meats with 10 ppm of TA added had significantly (p ≤ 0.05) lower lipid and protein oxidation than other treatments during storage. In addition, TA at 10 ppm level maintained the highest color a*- and L*-values during storage. Cooked chicken breast meat with 5 and 10 ppm TA added produced significantly (p ≤ 0.05) lower amounts of off-odor volatiles than other treatments. Among the volatile compounds, the amount of hexanal increased rapidly during storage for cooked meat. However, meats with 5 and 10 ppm TA added showed the lowest amount of hexanal and other aldehydes related to lipid oxidation, indicating a strong antioxidant effect of TA in cooked chicken breast meat. Furthermore, the differences in aldehydes among the treatments were bigger in cooked than in raw meat, indicating that the antioxidant effect of TA in cooked meat was greater than that in raw meat. Therefore, TA at >5 ppm can be used as a good natural preservative in cooked chicken meat to maintain its quality during storage. PMID:27304971

Structural characterization of the lipids A of three Bordetella bronchiseptica strains: variability of fatty acid substitution.

PubMed Central

Zarrouk, H; Karibian, D; Bodie, S; Perry, M B; Richards, J C; Caroff, M

1997-01-01

The structures of lipids A isolated from the lipopolysaccharides (LPSs; endotoxins) of three different pathogenic Bordetella bronchiseptica strains were investigated by chemical composition and methylation analysis, gas chromatography-mass spectrometry, nuclear magnetic resonance, and plasma desorption mass spectrometry (PDMS). The analyses revealed that the LPSs contain the classical lipid A bisphosphorylated beta-(1-->6)-linked D-glucosamine disaccharide with hydroxytetradecanoic acid in amide linkages. Their structures differ from that of the lipid A of Bordetella pertussis endotoxin by the replacement of hydroxydecanoic acid on the C-3 position with hydroxydodecanoic acid or dodecanoic acid and the presence of variable amounts of hexadecanoic acid. The dodecanoic acid is the first nonhydroxylated fatty acid to be found directly linked to a lipid A glucosamine. The lipids A were heterogeneous and composed of one to three major and several minor molecular species. The fatty acids in ester linkage were localized by PDMS of chemically modified lipids A. B. pertussis lipids A are usually hypoacylated with respect to those of enterobacterial lipids A. However, one of the three B. bronchiseptica strains had a major hexaacylated molecular species. C-4 and C-6' hydroxyl groups of the backbone disaccharide were unsubstituted, the latter being the proposed attachment site of the polysaccharide. The structural variability seen in these three lipids A was unusual for a single species and may have consequences for the pathogenicity of this Bordetella species. PMID:9171426

Structural characterization of the lipids A of three Bordetella bronchiseptica strains: variability of fatty acid substitution.

PubMed

Zarrouk, H; Karibian, D; Bodie, S; Perry, M B; Richards, J C; Caroff, M

1997-06-01

The structures of lipids A isolated from the lipopolysaccharides (LPSs; endotoxins) of three different pathogenic Bordetella bronchiseptica strains were investigated by chemical composition and methylation analysis, gas chromatography-mass spectrometry, nuclear magnetic resonance, and plasma desorption mass spectrometry (PDMS). The analyses revealed that the LPSs contain the classical lipid A bisphosphorylated beta-(1-->6)-linked D-glucosamine disaccharide with hydroxytetradecanoic acid in amide linkages. Their structures differ from that of the lipid A of Bordetella pertussis endotoxin by the replacement of hydroxydecanoic acid on the C-3 position with hydroxydodecanoic acid or dodecanoic acid and the presence of variable amounts of hexadecanoic acid. The dodecanoic acid is the first nonhydroxylated fatty acid to be found directly linked to a lipid A glucosamine. The lipids A were heterogeneous and composed of one to three major and several minor molecular species. The fatty acids in ester linkage were localized by PDMS of chemically modified lipids A. B. pertussis lipids A are usually hypoacylated with respect to those of enterobacterial lipids A. However, one of the three B. bronchiseptica strains had a major hexaacylated molecular species. C-4 and C-6' hydroxyl groups of the backbone disaccharide were unsubstituted, the latter being the proposed attachment site of the polysaccharide. The structural variability seen in these three lipids A was unusual for a single species and may have consequences for the pathogenicity of this Bordetella species.

Lateral Diffusion of Peripheral Membrane Proteins on Supported Lipid Bilayers Is Controlled by the Additive Frictional Drags of 1) Bound Lipids and 2) Protein Domains Penetrating into the Bilayer Hydrocarbon Core

PubMed Central

Ziemba, Brian P.; Falke, Joseph J.

2013-01-01

Peripheral membrane proteins bound to lipids on bilayer surfaces play central roles in a wide array of cellular processes, including many signaling pathways. These proteins diffuse in the plane of the bilayer and often undergo complex reactions involving the binding of regulatory and substrate lipids and proteins they encounter during their 2-D diffusion. Some peripheral proteins, for example pleckstrin homology (PH) domains, dock to the bilayer in a relatively shallow position with little penetration into the bilayer. Other peripheral proteins exhibit more complex bilayer contacts, for example classical protein kinase C isoforms (PKCs) bind as many as six lipids in stepwise fashion, resulting in the penetration of three PKC domains (C1A, C1B, C2) into the bilayer headgroup and hydrocarbon regions. A molecular understanding of the molecular features that control the diffusion speeds of proteins bound to supported bilayers would enable key molecular information to be extracted from experimental diffusion constants, revealing protein-lipid and protein-bilayer interactions difficult to study by other methods. The present study investigates a range of 11 different peripheral protein constructs comprised by 1 to 3 distinct domains (PH, C1A, C1B, C2, anti-lipid antibody). By combining these constructs with various combinations of target lipids, the study measures 2-D diffusion constants on supported bilayers for 17 different protein-lipid complexes. The resulting experimental diffusion constants, together with the known membrane interaction parameters of each complex, are used to analyze the molecular features correlated with diffusional slowing and bilayer friction. The findings show that both 1) individual bound lipids and 2) individual protein domains that penetrate into the hydrocarbon core make additive contributions to the friction against the bilayer, thereby defining the 2-D diffusion constant. An empirical formula is developed that accurately estimates the

Lateral diffusion of peripheral membrane proteins on supported lipid bilayers is controlled by the additive frictional drags of (1) bound lipids and (2) protein domains penetrating into the bilayer hydrocarbon core.

PubMed

Ziemba, Brian P; Falke, Joseph J

2013-01-01

Peripheral membrane proteins bound to lipids on bilayer surfaces play central roles in a wide array of cellular processes, including many signaling pathways. These proteins diffuse in the plane of the bilayer and often undergo complex reactions involving the binding of regulatory and substrate lipids and proteins they encounter during their 2D diffusion. Some peripheral proteins, for example pleckstrin homology (PH) domains, dock to the bilayer in a relatively shallow position with little penetration into the bilayer. Other peripheral proteins exhibit more complex bilayer contacts, for example classical protein kinase C isoforms (PKCs) bind as many as six lipids in stepwise fashion, resulting in the penetration of three PKC domains (C1A, C1B, C2) into the bilayer headgroup and hydrocarbon regions. A molecular understanding of the molecular features that control the diffusion speeds of proteins bound to supported bilayers would enable key molecular information to be extracted from experimental diffusion constants, revealing protein-lipid and protein-bilayer interactions difficult to study by other methods. The present study investigates a range of 11 different peripheral protein constructs comprised by 1-3 distinct domains (PH, C1A, C1B, C2, anti-lipid antibody). By combining these constructs with various combinations of target lipids, the study measures 2D diffusion constants on supported bilayers for 17 different protein-lipid complexes. The resulting experimental diffusion constants, together with the known membrane interaction parameters of each complex, are used to analyze the molecular features correlated with diffusional slowing and bilayer friction. The findings show that both (1) individual bound lipids and (2) individual protein domains that penetrate into the hydrocarbon core make additive contributions to the friction against the bilayer, thereby defining the 2D diffusion constant. An empirical formula is developed that accurately estimates the diffusion

Characterization of protein, lipid and mineral contents in common Norwegian seaweeds and evaluation of their potential as food and feed.

PubMed

Maehre, Hanne K; Malde, Marian K; Eilertsen, Karl-Erik; Elvevoll, Edel O

2014-12-01

The objectives of this study were to examine protein and amino acid composition, lipid and fatty acid composition, along with a range of essential minerals in common Norwegian seaweed species representing the red (Palmaria palmata and Vertebrata lanosa), green (Cladophora rupestris, Enteromorpha intestinalis and Ulva lactuca) and brown (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Fucus vesiculosus and Pelvetia canaliculata) classes and assess their potential as alternatives to cereals in food and feed. As macroalgae accumulate heavy metals, arsenic, cadmium and mercury were also analyzed. Proteins ranged from 34 to 123 g kg(-1) dry weight (DW) and the essential amino acid levels may cover both human and salmonid requirements. Lipids were low (6-58 g kg(-1) DW), but the red algae had high relative content of long-chained omega-3 fatty acids (32-34 % of the fatty acids). Iodine contents were particularly high in the Laminaria species. Of the heavy metals only arsenic levels may be of concern. In total, the red alga P. palmata was regarded as the best alternative to cereals in food and feed. For several of the other species, single-component extraction for the ingredients market may be better than using the whole product. © 2014 Society of Chemical Industry.

Lipid and fatty acid compositions of cod ( Gadus morhua), haddock ( Melanogrammus aeglefinus) and halibut ( Hippoglossus hippoglossus)

NASA Astrophysics Data System (ADS)

Zeng, Duan; Mai, Kangsen; Ai, Qinghui; Milley, Joyce E.; Lall, Santosh P.