Journal articles: 'Lipid membranes Biotechnology'

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Jackman, Joshua, Wolfgang Knoll, and Nam-Joon Cho. "Biotechnology Applications of Tethered Lipid Bilayer Membranes." Materials 5, no. 12 (December 7, 2012): 2637–57. http://dx.doi.org/10.3390/ma5122637.

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Efimova, S. S., T. E. Tertychnaya, S. N. Lavrenov, and O. S. Ostroumova. "The Mechanisms of Action of Triindolylmethane Derivatives on Lipid Membranes." Acta Naturae 11, no. 3 (September 15, 2019): 38–45. http://dx.doi.org/10.32607/20758251-2019-11-3-38-45.

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The effects of new synthetic antibacterial agents - tris(1-pentyl-1H-indol-3-yl)methylium chloride (LCTA-1975) and (1-(4-(dimethylamino)-2,5-dioxo-2,5-dihydro-1H-pyrrol-3-yl)-1H-indol-3-yl)bis(1-propyl- 1H-indol-3-yl)methylium chloride (LCTA-2701 - on model lipid membranes were studied. The ability of the tested agents to form ion-conductive transmembrane pores, influence the electrical stability of lipid bilayers and the phase transition of membrane lipids, and cause the deformation and fusion of lipid vesicles was investigated. It was established that both compounds exert a strong detergent effect on model membranes. The results of differential scanning microcalorimetry and measuring of the threshold transmembrane voltage that caused membrane breakdown before and after adsorption of LCTA-1975 and LCTA-2701 indicated that both agents cause disordering of membrane lipids. Synergism of the uncoupling action of antibiotics and the alkaloid capsaicin on model lipid membranes was shown. The threshold concentration of the antibiotic that caused an increase in the ion permeability of the lipid bilayer depended on the membrane lipid composition. It was lower by an order of magnitude in the case of negatively charged lipid bilayers than for the uncharged membranes. This can be explained by the positive charge of the tested agents. At the same time, LCTA-2701 was characterized by greater efficiency than LCTA-1975. In addition to its detergent action, LCTA-2701 can induce ion-permeable transmembrane pores: step-like current fluctuations corresponding to the opening and closing of individual ion channels were observed. The difference in the mechanisms of action might be related to the structural features of the antibiotic molecules: in the LCTA-1975 molecule, all three substituents at the nitrogen atoms of the indole rings are identical and represent n-alkyl (pentyl) groups, while LCTA-2701 contains a maleimide group, along with two alkyl substituents (n-propyl). The obtained results might be relevant to our understanding of the mechanism of action of new antibacterial agents, explaining the difference in the selectivity of action of the tested agents on the target microorganisms and their toxicity to human cells. Model lipid membranes should be used in further studies of the trends in the modification and improvement of the structures of new antibacterial agents.

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Schuster, Bernhard, and Uwe B. Sleytr. "S-layer-supported lipid membranes." Reviews in Molecular Biotechnology 74, no. 3 (September 2000): 233–54. http://dx.doi.org/10.1016/s1389-0352(00)00014-3.

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Beard, Jason, George S. Attard, and Matthew J. Cheetham. "Integrative feedback and robustness in a lipid biosynthetic network." Journal of The Royal Society Interface 5, no. 22 (October 16, 2007): 533–43. http://dx.doi.org/10.1098/rsif.2007.1155.

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The homeostatic control of membrane lipid composition appears to be of central importance for cell functioning and survival. However, while lipid biosynthetic reaction networks have been mapped in detail, the underlying control architecture which underpins these networks remains elusive. A key problem in determining the control architectures of lipid biosynthetic pathways, and the mechanisms through which control is achieved, is that the compositional complexity of lipid membranes makes it difficult to determine which membrane parameter is under homeostatic control. Recently, we reported that membrane stored elastic energy provides a physical feedback signal which modulates the activity in vitro of CTP:phosphocholine cytidylyltransferase (CCT), an extrinsic membrane enzyme which catalyses a key step in the synthesis of phosphatidylcholine lipids in the Kennedy pathway (Kennedy 1953 J. Am. Chem. Soc . 75 , 249–250). We postulate that stored elastic energy may be the main property of membranes that is under homeostatic control. Here we report the results of simulations based on this postulate, which reveal a possible control architecture for lipid biosynthesis networks in vivo .

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Schuster, Bernhard, and Uwe B. Sleytr. "Biomimetic interfaces based on S-layer proteins, lipid membranes and functional biomolecules." Journal of The Royal Society Interface 11, no. 96 (July 6, 2014): 20140232. http://dx.doi.org/10.1098/rsif.2014.0232.

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Designing and utilization of biomimetic membrane systems generated by bottom-up processes is a rapidly growing scientific and engineering field. Elucidation of the supramolecular construction principle of archaeal cell envelopes composed of S-layer stabilized lipid membranes led to new strategies for generating highly stable functional lipid membranes at meso- and macroscopic scale. In this review, we provide a state-of-the-art survey of how S-layer proteins, lipids and polymers may be used as basic building blocks for the assembly of S-layer-supported lipid membranes. These biomimetic membrane systems are distinguished by a nanopatterned fluidity, enhanced stability and longevity and, thus, provide a dedicated reconstitution matrix for membrane-active peptides and transmembrane proteins. Exciting areas in the (lab-on-a-) biochip technology are combining composite S-layer membrane systems involving specific membrane functions with the silicon world. Thus, it might become possible to create artificial noses or tongues, where many receptor proteins have to be exposed and read out simultaneously. Moreover, S-layer-coated liposomes and emulsomes copying virus envelopes constitute promising nanoformulations for the production of novel targeting, delivery, encapsulation and imaging systems.

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Dymond, Marcus K., Charlotte V. Hague, Anthony D. Postle, and George S. Attard. "An in vivo ratio control mechanism for phospholipid homeostasis: evidence from lipidomic studies." Journal of The Royal Society Interface 10, no. 80 (March 6, 2013): 20120854. http://dx.doi.org/10.1098/rsif.2012.0854.

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While it is widely accepted that the lipid composition of eukaryotic membranes is under homeostatic control, the mechanisms through which cells sense lipid composition are still the subject of debate. It has been postulated that membrane curvature elastic energy is the membrane property that is regulated by cells, and that lipid composition is maintained by a ratio control function derived from the concentrations of type II and type 0 lipids, weighted appropriately. We assess this proposal by seeking a signature of ratio control in quantified lipid composition data obtained by electrospray ionization mass spectrometry from over 40 independent asynchronous cell populations. Our approach revealed the existence of a universal ‘pivot’ lipid, which marks the boundary between type 0 lipids and type II lipids, and which is invariant between different cell types or cells grown under different conditions. The presence of such a pivot species is a distinctive signature of the operation in vivo , in human cell lines, of a control function that is consistent with the hypothesis that membrane elastic energy is homeostatically controlled.

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Avis, Tyler J., Mélanie Michaud, and Russell J. Tweddell. "Role of Lipid Composition and Lipid Peroxidation in the Sensitivity of Fungal Plant Pathogens to Aluminum Chloride and Sodium Metabisulfite." Applied and Environmental Microbiology 73, no. 9 (March 2, 2007): 2820–24. http://dx.doi.org/10.1128/aem.02849-06.

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ABSTRACT Aluminum chloride and sodium metabisulfite have shown high efficacy at low doses in controlling postharvest pathogens on potato tubers. Direct effects of these two salts included the loss of cell membrane integrity in exposed pathogens. In this work, four fungal potato pathogens were studied in order to elucidate the role of membrane lipids and lipid peroxidation in the relative sensitivity of microorganisms exposed to these salts. Inhibition of mycelial growth in these fungi varied considerably and revealed sensitivity groups within the tested fungi. Analysis of fatty acids in these fungi demonstrated that sensitivity was related to high intrinsic fatty acid unsaturation. When exposed to the antifungal salts, sensitive fungi demonstrated a loss of fatty acid unsaturation, which was accompanied by an elevation in malondialdehyde content (a biochemical marker of lipid peroxidation). Our data suggest that aluminum chloride and sodium metabisulfite could induce lipid peroxidation in sensitive fungi, which may promote the ensuing loss of integrity in the plasma membrane. This direct effect on fungal membranes may contribute, at least in part, to the observed antimicrobial effects of these two salts.

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Huffer, Sarah, Melinda E. Clark, Jonathan C. Ning, Harvey W. Blanch, and Douglas S. Clark. "Role of Alcohols in Growth, Lipid Composition, and Membrane Fluidity of Yeasts, Bacteria, and Archaea." Applied and Environmental Microbiology 77, no. 18 (July 22, 2011): 6400–6408. http://dx.doi.org/10.1128/aem.00694-11.

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ABSTRACTIncreased membrane fluidity, which causes cofactor leakage and loss of membrane potential, has long been documented as a cause for decreased cell growth during exposure to ethanol, butanol, and other alcohols. Reinforcement of the membrane with more complex lipid components is thus thought to be beneficial for the generation of more tolerant organisms. In this study, organisms with more complex membranes, namely, archaea, did not maintain high growth rates upon exposure to alcohols, indicating that more complex lipids do not necessarily fortify the membrane against the fluidizing effects of alcohols. In the presence of alcohols, shifts in lipid composition to more saturated and unbranched lipids were observed in most of the organisms tested, including archaea, yeasts, and bacteria. However, these shifts did not always result in a decrease in membrane fluidity or in greater tolerance of the organism to alcohol exposure. In general, organisms tolerating the highest concentrations of alcohols maintained membrane fluidity after alcohol exposure, whereas organisms that increased membrane rigidity were less tolerant. Altered lipid composition was a common response to alcohol exposure, with the most tolerant organisms maintaining a modestly fluid membrane. Our results demonstrate that increased membrane fluidity is not the sole cause of growth inhibition and that alcohols may also denature proteins within the membrane and cytosol, adversely affecting metabolism and decreasing cell growth.

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Moore, Eli K., Ellen C. Hopmans, W. Irene C. Rijpstra, Laura Villanueva, Svetlana N. Dedysh, Irina S. Kulichevskaya, Hans Wienk, Frans Schoutsen, and Jaap S. Sinninghe Damsté. "Novel Mono-, Di-, and Trimethylornithine Membrane Lipids in Northern Wetland Planctomycetes." Applied and Environmental Microbiology 79, no. 22 (August 30, 2013): 6874–84. http://dx.doi.org/10.1128/aem.02169-13.

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ABSTRACTNorthern peatlands represent a significant global carbon store and commonly originate fromSphagnummoss-dominated wetlands. These ombrotrophic ecosystems are rain fed, resulting in nutrient-poor, acidic conditions. Members of the bacterial phylumPlanctomycetesare highly abundant and appear to play an important role in the decomposition ofSphagnum-derived litter in these ecosystems. High-performance liquid chromatography coupled to high-resolution accurate-mass mass spectrometry (HPLC-HRAM/MS) analysis of lipid extracts of four isolated planctomycetes from wetlands of European north Russia revealed novel ornithine membrane lipids (OLs) that are mono-, di-, and trimethylated at the ε-nitrogen position of the ornithine head group. Nuclear magnetic resonance (NMR) analysis of the isolated trimethylornithine lipid confirmed the structural identification. Similar fatty acid distributions between mono-, di-, and trimethylornithine lipids suggest that the three lipid classes are biosynthetically linked, as in the sequential methylation of the terminal nitrogen in phosphatidylethanolamine to produce phosphatidylcholine. The mono-, di-, and trimethylornithine lipids described here represent the first report of methylation of the ornithine head groups in biological membranes. Various bacteria are known to produce OLs under phosphorus limitation or fatty-acid-hydroxylated OLs under thermal or acid stress. The sequential methylation of OLs, leading to a charged choline-like moiety in the trimethylornithine lipid head group, may be an adaptation to provide membrane stability under acidic conditions without the use of scarce phosphate in nutrient-poor ombrotrophic wetlands.

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Efimova, S. S., and O. S. Ostroumova. "Dipole Modifiers Regulate Lipid Lateral Heterogeneity in Model Membranes." Acta Naturae 9, no. 2 (June 15, 2017): 67–74. http://dx.doi.org/10.32607/20758251-2017-9-2-67-74.

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In this study we report on experimental observations of giant unilamellar liposomes composed of ternary mixtures of cholesterol (Chol), phospholipids with relatively low Tmelt (DOPC, POPC, or DPoPC) and high Tmelt (sphingomyelin (SM), or tetramyristoyl cardiolipin (TMCL)) and their phase behaviors in the presence and absence of dipole modifiers. It was shown that the ratios of liposomes exhibiting noticeable phase separation decrease in the series POPC, DOPC, DPoPC regardless of any high-Tmelt lipid. Substitution of SM for TMCL led to increased lipid phase segregation. Taking into account the fact that the first and second cases corresponded to a reduction in the thickness of the lipid domains enriched in low- and high-Tmelt lipids, respectively, our findings indicate that the phase behavior depends on thickness mismatch between the ordered and disordered domains. The dipole modifiers, flavonoids and styrylpyridinium dyes, reduced the phase segregation of membranes composed of SM, Chol, and POPC (or DOPC). The other ternary lipid mixtures tested were not affected by the addition of dipole modifiers. It is suggested that dipole modifiers address the hydrophobic mismatch through fluidization of the ordered and disordered domains. The ability of a modifier to partition into the membrane and fluidize the domains was dictated by the hydrophobicity of modifier molecules, their geometric shape, and the packing density of domain-forming lipids. Phloretin, RH 421, and RH 237 proved the most potent among all the modifiers examined.

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RISKE, KARIN A., NATALYA BEZLYEPKINA, REINHARD LIPOWSKY, and RUMIANA DIMOVA. "ELECTROFUSION OF MODEL LIPID MEMBRANES VIEWED WITH HIGH TEMPORAL RESOLUTION." Biophysical Reviews and Letters 01, no. 04 (October 2006): 387–400. http://dx.doi.org/10.1142/s179304800600032x.

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The interaction of electric fields with lipid membranes and cells has been extensively studied in the last decades. The phenomena of electroporation and electrofusion are of particular interest because of their widespread use in cell biology and biotechnology. Giant vesicles, being of cell size and convenient for microscopy observations, are the simplest model of the cell membrane. However, optical microscopy observation of effects caused by electric DC pulses on giant vesicles is difficult because of the short duration of the pulse. Recently this difficulty has been overcome in our lab. Using a digital camera with high temporal resolution, we were able to access vesicle fusion dynamics on a sub-millisecond time scale. In this report, we present some observations on electrodeformation and –poration of single vesicles followed by an extensive study on the electrofusion of vesicle couples. Finally, we suggest an attractive approach for creating multidomain vesicles using electrofusion and present some preliminary results on the effect of membrane stiffness on the fusion dynamics.

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Schnurr, J. A., J. Shockey, and John Browse. "Characterization of an acyl-CoA synthetase from Arabidopsis thaliana." Biochemical Society Transactions 28, no. 6 (December 1, 2000): 957–58. http://dx.doi.org/10.1042/bst0280957.

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One of the major goals of modern plant biotechnology is to manipulate lipid metabolism in oilseed crops to produce new and improved edible and industrial vegetable oils. Lipids constitute the structural components of cellular membranes and act as sources of energy for the germinating seed and are therefore essential to plant cell function. Both de novo synthesis and modification of existing lipids are dependent on the activity of acyl-CoA synthetases (ACSs). To date, ACSs have been recalcitrant to traditional methods of purification due to their association with membranes. In our laboratory, several isoforms of ACSs have been identified in Arabidopsis thaliana. Reverse genetics allowed us to identify a mutant containing a transfer DNA-interrupted ACS gene. Results will be presented that describe the isolation and characterization of this mutant. The elucidation of the specific roles of ACSs will lead to a greater understanding of plant lipid metabolism.

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Bergeron, Annick, Christine Guillemette, Marc-André Sirard, and François J. Richard. "Active 3ʹ–5ʹ cyclic nucleotide phosphodiesterases are present in detergent-resistant membranes of mural granulosa cells." Reproduction, Fertility and Development 29, no. 4 (2017): 778. http://dx.doi.org/10.1071/rd15243.

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Lipids rafts are specialised membrane microdomains involved in cell signalling that can be isolated as detergent-resistant membranes (DRMs). The second messenger cyclic AMP (cAMP) has a central role in cell signalling in the ovary and its degradation is carried out by the phosphodiesterase (PDE) enzyme family. We hypothesised that PDEs could be functionally present in the lipid rafts of porcine mural granulosa cell membranes. PDE6C, PDE8A and PDE11A were detected by dot blot in the DRMs and the Triton-soluble fraction of the mural granulosa cells membrane and the cytosol. As shown by immunocytochemistry, PDEs showed clear immunostaining in mural granulosa cell membranes and the cytosol. Interestingly, cAMP–PDE activity was 18 times higher in the DRMs than in the Triton-soluble fraction of cell membranes and was 7.7 times higher in the cytosol than in the DRMs. cAMP–PDE activity in mural granulosa cells was mainly contributed by the PDE8 and PDE11 families. This study shows that PDEs from the PDE8 and PDE11 families are present in mural granulosa cells and that the cAMP–PDE activity is mainly contributed by the cytosol. In the cell membrane, the cAMP–PDE activity is mainly contributed by the DRMs. In addition, receptors for prostaglandin E2 and LH, two G-protein-coupled receptors, are present in lipid rafts and absent from the non-raft fraction of the granulosa cell membrane. These results suggest that in these cells, the lipid rafts exist as a cell-signalling platform and PDEs are one of the key enzyme families present in the raft.

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Campbell, Scott D., Karen J. Regina, and Evan D. Kharasch. "Significance of Lipid Composition in a Blood-Brain Barrier–Mimetic PAMPA Assay." Journal of Biomolecular Screening 19, no. 3 (August 14, 2013): 437–44. http://dx.doi.org/10.1177/1087057113497981.

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Endothelial cells forming the blood-brain barrier limit drug access into the brain, due to tight junctions, membrane drug transporters, and unique lipid composition. Passive permeability, thought to mediate drug access, is typically tested using porcine whole-brain lipid. However, human endothelial cell lipid composition differs. This investigation evaluated the influence of lipid composition on passive permeability across artificial membranes. Permeability of CNS-active drugs across an immobilized lipid membrane was determined using three lipid models: crude extract from whole pig brain, human brain microvessel lipid, and microvessel lipid plus cholesterol. Lipids were immobilized on polyvinylidene difluoride, forming donor and receiver chambers, in which drug concentrations were measured after 2 h. The log of effective permeability was then calculated using the measured concentrations. Permeability of small, neutral compounds was unaffected by lipid composition. Several structurally diverse drugs were highly permeable in porcine whole-brain lipid but one to two orders of magnitude less permeable across human brain endothelial cell lipid. Inclusion of cholesterol had the greatest influence on bulky amphipathic compounds such as glucuronide conjugates. Lipid composition markedly influences passive permeability. This was most apparent for charged or bulky compounds. These results demonstrate the importance of using species-specific lipid models in passive permeability assays.

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Fonvieille, Jean-Louis, Jane-Marie Touze-Soulet, and Charles Montant. "Les systèmes membranaires de Scopulariopsis brevicaulis. II. Étude comparée de leur composition lipidique." Canadian Journal of Microbiology 33, no. 1 (January 1, 1987): 78–81. http://dx.doi.org/10.1139/m87-013.

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Biochemical studies of Scopulariopsis brevicaulis membranes (except mitochondrial membranes), in particular their lipid composition, were undertaken using plasma membranes and fractions containing smooth endoplasmic reticulum and Golgi apparatus membranes. The results obtained by two separation techniques, a continuous Percoll gradient and a discontinuous sucrose gradient centrifugation, were similar. Depending on the isolation method used, the plasma membrane contained 30 or 33% protein and 23 or 30% lipid of which 16.5 or 18% was phospholipid. The sterol/phospholipid ratio was 1.98 or 2.28. The endoplasmic reticulum + Golgi fraction contained 21 or 26.7% protein and 43 or 50% lipid of which 7 or 10% was phospholipid. The sterol/phospholipid ratio was 0.85 or 0.81.

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Becker, Kevin W., Felix J. Elling, Marcos Y. Yoshinaga, Andrea Söllinger, Tim Urich, and Kai-Uwe Hinrichs. "Unusual Butane- and Pentanetriol-Based Tetraether Lipids in Methanomassiliicoccus luminyensis, a Representative of the Seventh Order of Methanogens." Applied and Environmental Microbiology 82, no. 15 (May 13, 2016): 4505–16. http://dx.doi.org/10.1128/aem.00772-16.

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ABSTRACTA new clade of archaea has recently been proposed to constitute the seventh methanogenic order, theMethanomassiliicoccales, which is related to theThermoplasmatalesand the uncultivated archaeal clades deep-sea hydrothermal ventEuryarchaeotagroup 2 and marine group IIEuryarchaeotabut only distantly related to other methanogens. In this study, we investigated the membrane lipid composition ofMethanomassiliicoccus luminyensis, the sole cultured representative of this seventh order. The lipid inventory ofM. luminyensiscomprises a unique assemblage of novel lipids as well as lipids otherwise typical for thermophilic, methanogenic, or halophilic archaea. For instance, glycerol sesterpanyl-phytanyl diether core lipids found mainly in halophilic archaea were detected, and so were compounds bearing either heptose or methoxylated glycosidic head groups, neither of which have been reported so far for other archaea. The absence of quinones or methanophenazines is consistent with a biochemistry of methanogenesis different from that of the methanophenazine-containing methylotrophic methanogens. The most distinctive characteristic of the membrane lipid composition ofM. luminyensis, however, is the presence of tetraether lipids in which one glycerol backbone is replaced by either butane- or pentanetriol, i.e., lipids recently discovered in marine sediments. Butanetriol dibiphytanyl glycerol tetraether (BDGT) constitutes the most abundant core lipid type (>50% relative abundance) inM. luminyensis. We have thus identified a source for these unusual orphan lipids. The complementary analysis of diverse marine sediment samples showed that BDGTs are widespread in anoxic layers, suggesting an environmental significance ofMethanomassiliicoccalesand/or related BDGT producers beyond gastrointestinal tracts.IMPORTANCECellular membranes of members of all three domains of life,Archaea,Bacteria, andEukarya, are largely formed by lipids in which glycerol serves as backbone for the hydrophobic alkyl chains. Recently, however, archaeal tetraether lipids with either butanetriol or pentanetriol as a backbone were identified in marine sediments and attributed to uncultured sediment-dwelling archaea. Here we show that the butanetriol-based dibiphytanyl tetraethers constitute the major lipids inMethanomassiliicoccus luminyensis, currently the only isolate of the novel seventh order of methanogens. Given the absence of these lipids in a large set of archaeal isolates, these compounds may be diagnostic for theMethanomassiliicoccalesand/or closely related archaea.

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Li, Jie, Michael L. Chikindas, Richard D. Ludescher, and Thomas J. Montville. "Temperature- and Surfactant-Induced Membrane Modifications That Alter Listeria monocytogenes Nisin Sensitivity by Different Mechanisms." Applied and Environmental Microbiology 68, no. 12 (December 2002): 5904–10. http://dx.doi.org/10.1128/aem.68.12.5904-5910.2002.

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ABSTRACT Nisin interacts with target membranes in four sequential steps: binding, insertion, aggregation, and pore formation. Alterations in membrane composition might influence any of these steps. We hypothesized that cold temperatures (10°C) and surfactant (0.1% Tween 20) in the growth medium would influence Listeria monocytogenes membrane lipid composition, membrane fluidity, and, as a result, sensitivity to nisin. Compared to the membranes of cells grown at 30°C, those of L. monocytogenes grown at 10°C had increased amounts of shorter, branched-chain fatty acids, increased fluidity (as measured by fluorescence anisotropy), and increased nisin sensitivity. When 0.1% Tween 20 was included in the medium and the cells were cultured at 30°C, there were complex changes in lipid composition. They did not influence membrane fluidity but nonetheless increased nisin sensitivity. Further investigation found that these cells had an increased ability to bind radioactively labeled nisin. This suggests that the modification of the surfactant-adapted cell membrane increased nisin sensitivity at the binding step and demonstrates that each of the four steps can contribute to nisin sensitivity.

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Robenek, Mirko J., Nicholas J. Severs, Karin Schlattmann, Gabriele Plenz, Klaus-Peter Zimmer, David Troyer, and Horst Robenek. "Lipids partition caveolin‐1 from ER membranes into lipid droplets: updating the model of lipid droplet biogenesis." FASEB Journal 18, no. 7 (March 4, 2004): 866–68. http://dx.doi.org/10.1096/fj.03-0782fje.

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El-Beyrouthy, Joyce, Michelle M. Makhoul-Mansour, Graham Taylor, Stephen A. Sarles, and Eric C. Freeman. "A new approach for investigating the response of lipid membranes to electrocompression by coupling droplet mechanics and membrane biophysics." Journal of The Royal Society Interface 16, no. 161 (December 2019): 20190652. http://dx.doi.org/10.1098/rsif.2019.0652.

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A new method for quantifying lipid–lipid interactions within biomimetic membranes undergoing electrocompression is demonstrated by coupling droplet mechanics and membrane biophysics. The membrane properties are varied by altering the lipid packing through the introduction of cholesterol. Pendant drop tensiometry is used to measure the lipid monolayer tension at an oil–water interface. Next, two lipid-coated aqueous droplets are manipulated into contact to form a bilayer membrane at their adhered interface. The droplet geometries are captured from two angles to provide accurate measurements of both the membrane area and the contact angle between the adhered droplets. Combining the monolayer tension and contact angle measurements enables estimations of the membrane tension with respect to lipid composition. Then, the membrane is electromechanically compressed using a transmembrane voltage. Electrostatic pressure, membrane tension and the work necessary for bilayer thinning are tracked, and a model is proposed to capture the mechanics of membrane compression. The results highlight that a previously unaccounted for energetic term is produced during compression, potentially reflecting changes in the lateral membrane structure. This residual energy is eliminated in cases with cholesterol mole fractions of 0.2 and higher, suggesting that cholesterol diminishes these adjustments.

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Stoilova-McPhie, Svetla. "Lipid nanotechnologies for structural studies of membrane-associated clotting proteins by cryo-electron microscopy." Nanotechnology Reviews 6, no. 1 (February 1, 2017): 127–37. http://dx.doi.org/10.1515/ntrev-2016-0066.

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AbstractBiological membranes surround all living cells, confining internal organelles and participating in a variety of essential cellular functions, such as signaling, electrolyte balance, and energy conversion. Cell membranes are structurally and chemically heterogeneous environment composed of numerous types of lipids arranged as a continuous bilayer. The assembly of protein complexes at the membrane surface is responsible for fundamental biological processes such as synaptic transmission, blood coagulation, and apoptosis. Resolving the macromolecular organization of these complexes at the membrane surface will help to understand the structural basis of their function and significance for the associated biological processes. In this review, we present our work on direct structure determination of membrane-bound clotting factors, specifically factor VIII (FVIII), by cryogenic electron microscopy (CryoEM). To resolve the FVIII membrane-bound organization, we have optimized lipid nanostructures resembling the activated platelet membrane. Combining structural CryoEM, capable of near-atomic resolution, with customized lipid nanotechnologies is a powerful approach to investigate how the cellular membrane can modulate protein function at close to physiological conditions. The outcome will open novel avenues for developing lipid nanotechnologies of diverse shapes and composition that can be optimized for various protein systems, germane for both drug delivery and macromolecular structure determination.

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Weatherill, E. E., H. L. E. Coker, M. R. Cheetham, and M. I. Wallace. "Urea-mediated anomalous diffusion in supported lipid bilayers." Interface Focus 8, no. 5 (August 17, 2018): 20180028. http://dx.doi.org/10.1098/rsfs.2018.0028.

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Diffusion in biological membranes is seldom simply Brownian motion; instead, the rate of diffusion is dependent on the time scale of observation and so is often described as anomalous. In order to help better understand this phenomenon, model systems are needed where the anomalous diffusion of the lipid bilayer can be tuned and quantified. We recently demonstrated one such model by controlling the excluded area fraction in supported lipid bilayers (SLBs) through the incorporation of lipids derivatized with polyethylene glycol. Here, we extend this work, using urea to induce anomalous diffusion in SLBs. By tuning incubation time and urea concentration, we produce bilayers that exhibit anomalous behaviour on the same scale as that observed in biological membranes.

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Balantič, Katja, Damijan Miklavčič, Igor Križaj, and Peter Kramar. "The Good and the Bad of Cell Membrane Electroporation." Acta Chimica Slovenica 68, no. 4 (December 15, 2021): 753–64. http://dx.doi.org/10.17344/acsi.2021.7198.

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Electroporation is used to increase the permeability of the cell membrane through high-voltage electric pulses. Nowadays, it is widely used in different areas, such as medicine, biotechnology, and the food industry. Electroporation induces the formation of hydrophilic pores in the lipid bilayer of cell membranes, to allow the entry or exit of molecules that cannot otherwise cross this hydrophobic barrier. In this article, we critically review the basic principles of electroporation, along with the advantages and drawbacks of this method. We discuss the effects of electroporation on the key components of biological membranes, as well as the main applications of this procedure in medicine, such as electrochemotherapy, gene electrotransfer, and tissue ablation. Finally, we define the most relevant challenges of this romising area of research.

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Hinks, Jamie, Wee Han Poh, Justin Jang Hann Chu, Joachim Say Chye Loo, Guillermo C. Bazan, Lynn E. Hancock, and Stefan Wuertz. "Oligopolyphenylenevinylene-Conjugated Oligoelectrolyte Membrane Insertion Molecules Selectively Disrupt Cell Envelopes of Gram-Positive Bacteria." Applied and Environmental Microbiology 81, no. 6 (January 9, 2015): 1949–58. http://dx.doi.org/10.1128/aem.03355-14.

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ABSTRACTThe modification of microbial membranes to achieve biotechnological strain improvement with exogenous small molecules, such as oligopolyphenylenevinylene-conjugated oligoelectrolyte (OPV-COE) membrane insertion molecules (MIMs), is an emerging biotechnological field. Little is known about the interactions of OPV-COEs with their target, the bacterial envelope. We studied the toxicity of three previously reported OPV-COEs with a selection of Gram-negative and Gram-positive organisms and demonstrated that Gram-positive bacteria are more sensitive to OPV-COEs than Gram-negative bacteria. Transmission electron microscopy demonstrated that these MIMs disrupt microbial membranes and that this occurred to a much greater degree in Gram-positive organisms. We used a number of mutants to probe the nature of MIM interactions with the microbial envelope but were unable to align the membrane perturbation effects of these compounds to previously reported membrane disruption mechanisms of, for example, cationic antimicrobial peptides. Instead, the data support the notion that OPV-COEs disrupt microbial membranes through a suspected interaction with diphosphatidylglycerol (DPG), a major component of Gram-positive membranes. The integrity of model membranes containing elevated amounts of DPG was disrupted to a greater extent by MIMs than those prepared fromEscherichia colitotal lipid extracts alone.

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Hyldgaard, Morten, Duncan S. Sutherland, Maria Sundh, Tina Mygind, and Rikke Louise Meyer. "Antimicrobial Mechanism of Monocaprylate." Applied and Environmental Microbiology 78, no. 8 (February 17, 2012): 2957–65. http://dx.doi.org/10.1128/aem.07224-11.

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ABSTRACTMonoglyceride esters of fatty acids occur naturally and encompass a broad spectrum of antimicrobial activity. Monocaprylate is generally regarded as safe (GRAS) and can function both as an emulsifier and as a preservative in food. However, knowledge about its mode of action is lacking. The aim of this study was therefore to elucidate the mechanism behind monocaprylate's antimicrobial effect. The cause of cell death inEscherichia coli,Staphylococcus xylosus, andZygosaccharomyces bailiiwas investigated by examining monocaprylate's effect on cell structure, membrane integrity, and its interaction with model membranes. Changes in cell structure were visible by atomic force microscopy (AFM), and propidium iodide staining showed membrane disruption, indicating the membrane as a site of action. This indication was confirmed by measuring calcein leakage from membrane vesicles exposed to monocaprylate. AFM imaging of supported lipid bilayers visualized the integration of monocaprylate into the liquid disordered, and not the solid ordered, phase of the membrane. The integration of monocaprylate was confirmed by quartz crystal microbalance measurements, showing an abrupt increase in mass and hydration of the membrane after exposure to monocaprylate above a threshold concentration. We hypothesize that monocaprylate destabilizes membranes by increasing membrane fluidity and the number of phase boundary defects. The sensitivity of cells to monocaprylate will therefore depend on the lipid composition, fluidity, and curvature of the membrane.

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Miller, Jr, R. R., F. Beranek, A. L. Anderson, S. D. Johnston, and B. Nixon. "Plasma and acrosomal membrane lipid content of saltwater crocodile spermatozoa." Reproduction, Fertility and Development 33, no. 9 (2021): 596. http://dx.doi.org/10.1071/rd21007.

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This study describes the chemical lipid composition of the sperm plasma and acrosomal membranes of the saltwater crocodile Crocodylus porosus with the aim of providing new insights into sperm physiology, particularly that associated with their preservation ex vivo. The specific fatty acid composition of the sperm plasma and acrosomal membranes is documented. The mean (±s.d.) ratio of unsaturated to saturated membrane fatty acids within the plasma membrane was 2.57±0.50, and was determined to be higher than a similar analysis of the lipids found in the acrosomal membrane (0.70±0.10). The saltwater crocodile sperm plasma membrane also contained remarkably high levels of cholesterol (mean (±s.d.) 40.7±4.5 nmol per 106 sperm cells) compared with the spermatozoa of other amniote species that have so far been documented. We suggest that this high cholesterol content could be conferring stability to the crocodile sperm membrane, allowing it to tolerate extreme osmotic fluxes and rapid changes in temperature. Our descriptive analysis now provides those interested in reptile and comparative sperm physiology an improved baseline database for interpreting biochemical changes associated with preservation pathology (e.g. cold shock and cryoinjury), epididymal sperm maturation and capacitation/acrosome reaction.

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Shao, Yong, Yongdong Jin, Jianlong Wang, Li Wang, Feng Zhao, and Shaojun Dong. "Conducting polymer polypyrrole supported bilayer lipid membranes." Biosensors and Bioelectronics 20, no. 7 (January 2005): 1373–79. http://dx.doi.org/10.1016/j.bios.2004.06.001.

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Rilfors, Leif, and Göran Lindblom. "Regulation of lipid composition in biological membranes—biophysical studies of lipids and lipid synthesizing enzymes." Colloids and Surfaces B: Biointerfaces 26, no. 1-2 (September 2002): 112–24. http://dx.doi.org/10.1016/s0927-7765(01)00310-1.

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Bar, Laure, George Cordoyiannis, Shova Neupane, Jonathan Goole, Patrick Grosfils, and Patricia Losada-Pérez. "Asymmetric Lipid Transfer between Zwitterionic Vesicles by Nanoviscosity Measurements." Nanomaterials 11, no. 5 (April 22, 2021): 1087. http://dx.doi.org/10.3390/nano11051087.

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The interest in nano-sized lipid vesicles in nano-biotechnology relies on their use as mimics for endosomes, exosomes, and nanocarriers for drug delivery. The interactions between nanoscale size lipid vesicles and cell membranes involve spontaneous interbilayer lipid transfer by several mechanisms, such as monomer transfer or hemifusion. Experimental approaches toward monitoring lipid transfer between nanoscale-sized vesicles typically consist of transfer assays by fluorescence microscopy requiring the use of labels or calorimetric measurements, which in turn require a large amount of sample. Here, the capability of a label-free surface-sensitive method, quartz crystal microbalance with dissipation monitoring (QCM-D), was used to monitor lipid transfer kinetics at minimal concentrations and to elucidate how lipid physicochemical properties influence the nature of the transfer mechanism and dictate its dynamics. By studying time-dependent phase transitions obtained from nanoviscosity measurements, the transfer rates (unidirectional or bidirectional) between two vesicle populations consisting of lipids with the same head group and differing alkyl chain length can be estimated. Lipid transfer is asymmetric and unidirectional from shorter-chain lipid donor vesicles to longer-chain lipid acceptor vesicles. The transfer is dramatically reduced when the vesicle populations are incubated at temperatures below the melting of one of the vesicle populations.

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Gao, Yiyi, Dangxin Mao, Jun Wu, Xiaogang Wang, Zhikun Wang, Guoquan Zhou, Liang Chen, Junlang Chen, and Songwei Zeng. "Carbon Nanotubes Translocation through a Lipid Membrane and Transporting Small Hydrophobic and Hydrophilic Molecules." Applied Sciences 9, no. 20 (October 12, 2019): 4271. http://dx.doi.org/10.3390/app9204271.

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Carbon nanotubes (CNTs) are extensively adopted in the applications of biotechnology and biomedicine. Their interactions with cell membranes are of great importance for understanding the toxicity of CNTs and the application of drug delivery. In this paper, we use atomic molecular dynamics simulations to study the permeation and orientation of pristine and functionalized CNTs in a lipid bilayer. Pristine CNT (PCNT) can readily permeate into the membrane and reside in the hydrophobic region without specific orientation. The insertion of PCNTs into the lipid bilayer is robust and independent on the lengths of PCNTs. Due to the presence of hydroxyl groups on both ends of the functionalized CNT (FCNT), FCNT prefers to stand upright in the lipid bilayer center. Compared with PCNT, FCNT is more suitable to be a bridge connecting the inner and outer lipid membrane. The inserted CNTs have no distinct effects on membrane structure. However, they may block the ion channels. In addition, preliminary explorations on the transport properties of CNTs show that the small hydrophobic molecule carbon dioxide can enter both PCNT and FCNT hollow channels. However, hydrophilic molecule urea is prone to penetrate the PCNT but finds it difficult to enter the FCNT. These results may provide new insights into the internalization of CNT in the lipid membrane and the transport properties of CNTs when embedded therein.

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Alves, Ana Catarina, Daniela Ribeiro, Miguel Horta, José L. F. C. Lima, Cláudia Nunes, and Salette Reis. "A biophysical approach to daunorubicin interaction with model membranes: relevance for the drug's biological activity." Journal of The Royal Society Interface 14, no. 133 (August 2017): 20170408. http://dx.doi.org/10.1098/rsif.2017.0408.

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Daunorubicin is extensively used in chemotherapy for diverse types of cancer. Over the years, evidence has suggested that the mechanisms by which daunorubicin causes cytotoxic effects are also associated with interactions at the membrane level. The aim of the present work was to study the interplay between daunorubicin and mimetic membrane models composed of different ratios of 1,2-dimyristoyl- sn -glycero- 3 -phosphocholine (DMPC), sphingomyelin (SM) and cholesterol (Chol). Several biophysical parameters were assessed using liposomes as mimetic model membranes. Thereby, the ability of daunorubicin to partition into lipid bilayers, its apparent location within the membrane and its effect on membrane fluidity were investigated. The results showed that daunorubicin has higher affinity for lipid bilayers composed of DMPC, followed by DMPC : SM, DMPC : Chol and lastly by DMPC : SM : Chol. The addition of SM or Chol into DMPC membranes not only increases the complexity of the model membrane but also decreases its fluidity, which, in turn, reduces the amount of anticancer drug that can partition into these mimetic models. Fluorescence quenching studies suggest a broad distribution of the drug across the bilayer thickness, with a preferential location in the phospholipid tails. The gathered data support that daunorubicin permeates all types of membranes to different degrees, interacts with phospholipids through electrostatic and hydrophobic bonds and causes alterations in the biophysical properties of the bilayers, namely in membrane fluidity. In fact, a decrease in membrane fluidity can be observed in the acyl region of the phospholipids. Ultimately, such outcomes can be correlated with daunorubicin's biological action, where membrane structure and lipid composition have an important role. In fact, the results indicate that the intercalation of daunorubicin between the phospholipids can also take place in rigid domains, such as rafts that are known to be involved in different receptor processes, which are important for cellular function.

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Henderson, Clark M., and David E. Block. "Examining the Role of Membrane Lipid Composition in Determining the Ethanol Tolerance of Saccharomyces cerevisiae." Applied and Environmental Microbiology 80, no. 10 (March 7, 2014): 2966–72. http://dx.doi.org/10.1128/aem.04151-13.

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ABSTRACTYeast (Saccharomyces cerevisiae) has an innate ability to withstand high levels of ethanol that would prove lethal to or severely impair the physiology of other organisms. Significant efforts have been undertaken to elucidate the biochemical and biophysical mechanisms of how ethanol interacts with lipid bilayers and cellular membranes. This research has implicated the yeast cellular membrane as the primary target of the toxic effects of ethanol. Analysis of model membrane systems exposed to ethanol has demonstrated ethanol's perturbing effect on lipid bilayers, and altering the lipid composition of these model bilayers can mitigate the effect of ethanol. In addition, cell membrane composition has been correlated with the ethanol tolerance of yeast cells. However, the physical phenomena behind this correlation are likely to be complex. Previous work based on often divergent experimental conditions and time-consuming low-resolution methodologies that limit large-scale analysis of yeast fermentations has fallen short of revealing shared mechanisms of alcohol tolerance inSaccharomyces cerevisiae. Lipidomics, a modern mass spectrometry-based approach to analyze the complex physiological regulation of lipid composition in yeast and other organisms, has helped to uncover potential mechanisms for alcohol tolerance in yeast. Recent experimental work utilizing lipidomics methodologies has provided a more detailed molecular picture of the relationship between lipid composition and ethanol tolerance. While it has become clear that the yeast cell membrane composition affects its ability to tolerate ethanol, the molecular mechanisms of yeast alcohol tolerance remain to be elucidated.

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Razza, Eduardo M., Mateus J. Sudano, Patricia K. Fontes, Fernanda F. Franchi, Katia Roberta A. Belaz, Priscila H. Santos, Anthony C. S. Castilho, et al. "Treatment with cyclic adenosine monophosphate modulators prior to in vitro maturation alters the lipid composition and transcript profile of bovine cumulus–oocyte complexes and blastocysts." Reproduction, Fertility and Development 30, no. 10 (2018): 1314. http://dx.doi.org/10.1071/rd17335.

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Mammalian oocytes resume meiosis spontaneously after removal from the ovarian follicle. We tested the effects of a 2-h prematuration treatment (Pre-IVM) with forskolin (FSK) and 3-isobutyl-1-methylxanthine (IBMX) in bovine cumulus–oocyte complexes (COCs) on the lipid content of oocytes and blastocysts, on the membrane lipid composition of blastocysts and on the transcriptional profiling of cumulus cells and blastocysts in a high-throughput platform. Embryonic development rates to the morula (mean 56.1%) or blastocyst (mean 26.3%) stages were unaffected by treatment. Lipid content was not affected after Pre-IVM, but was increased after IVM in treated oocytes. Conversely, the lipid content was reduced in Pre-IVM blastocysts. Pre-IVM COCs generated blastocysts containing blastomeres with more unsaturated lipids in their membranes. Pre-IVM also altered the relative abundance of 31 gene transcripts after 2 h and 16 transcripts after 24 h in cumulus cells, while seven transcripts were altered in blastocysts. Our results suggest that the Pre-IVM treatment affected the lipid composition and transcriptional profiles of COCs and blastocysts. Therefore, Pre-IVM with FSK and IBMX could be used either to prevent spontaneous meiotic resumption during IVM or to modulate lipid composition in the membrane and cytoplasm of blastocysts, potentially improving bovine embryos.

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Marín-Medina, Nathaly, Diego Alejandro Ramírez, Steve Trier, and Chad Leidy. "Mechanical properties that influence antimicrobial peptide activity in lipid membranes." Applied Microbiology and Biotechnology 100, no. 24 (November 11, 2016): 10251–63. http://dx.doi.org/10.1007/s00253-016-7975-9.

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Sandin, Suzanne I., and Eva de Alba. "Quantitative Studies on the Interaction between Saposin-like Proteins and Synthetic Lipid Membranes." Methods and Protocols 5, no. 1 (February 16, 2022): 19. http://dx.doi.org/10.3390/mps5010019.

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Members of the saposin-fold protein family and related proteins sharing a similar fold (saposin-like proteins; SAPLIP) are peripheral-membrane binding proteins that perform essential cellular functions. Saposins and SAPLIPs are abundant in both plant and animal kingdoms, and peripherally bind to lipid membranes to play important roles in lipid transfer and hydrolysis, defense mechanisms, surfactant stabilization, and cell proliferation. However, quantitative studies on the interaction between proteins and membranes are challenging due to the different nature of the two components in relation to size, structure, chemical composition, and polarity. Using liposomes and the saposin-fold member saposin C (sapC) as model systems, we describe here a method to apply solution NMR and dynamic light scattering to study the interaction between SAPLIPs and synthetic membranes at the quantitative level. Specifically, we prove with NMR that sapC binds reversibly to the synthetic membrane in a pH-controlled manner and show the dynamic nature of its fusogenic properties with dynamic light scattering. The method can be used to infer the optimal pH for membrane binding and to determine an apparent dissociation constant (KDapp) for protein-liposome interaction. We propose that these experiments can be applied to other proteins sharing the saposin fold.

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Dymond, Marcus, George Attard, and Anthony D. Postle. "Testing the hypothesis that amphiphilic antineoplastic lipid analogues act through reduction of membrane curvature elastic stress." Journal of The Royal Society Interface 5, no. 28 (April 15, 2008): 1371–86. http://dx.doi.org/10.1098/rsif.2008.0041.

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The alkyllysophospholipid (ALP) analogues Mitelfosine and Edelfosine are anticancer drugs whose mode of action is still the subject of debate. It is agreed that the primary interaction of these compounds is with cellular membranes. Furthermore, the membrane-associated protein CTP: phosphocholine cytidylyltransferase (CCT) has been proposed as the critical target. We present the evaluation of our hypothesis that ALP analogues disrupt membrane curvature elastic stress and inhibit membrane-associated protein activity (e.g. CCT), ultimately resulting in apoptosis. This hypothesis was tested by evaluating structure–activity relationships of ALPs from the literature. In addition we characterized the lipid typology, cytotoxicity and critical micelle concentration of novel ALP analogues that we synthesized. Overall we find the literature data and our experimental data provide excellent support for the hypothesis, which predicts that the most potent ALP analogues will be type I lipids.

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Efimova, S. S., and O. S. Ostroumova. "Modifiers of the Dipole Potential of Lipid Bilayers." Acta Naturae 7, no. 4 (December 15, 2015): 70–79. http://dx.doi.org/10.32607/20758251-2015-7-4-70-79.

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This paper assesses the magnitude of change in the dipole potential (d) of membranes caused by the adsorption of modifiers on lipid bilayers of various compositions. We tested flavonoids, muscle relaxants, thyroid hormones, and xanthene and styrylpyridinium dyes in order to assess their dipole-modifying properties. A quantitative description of the modifying action of flavonoids, muscle relaxants, thyroid hormones, and xanthene dyes is shown as the ratio of the maximum change in the bilayer dipole potential upon saturation and the absolute d value of the unmodified membrane. The slopes of the linear relationship between the increase in the dipole potential of phospholipid bilayers and the concentration of styrylpyridinium dyes in membrane-bathing solutions were found. We described the relationships between the change in d and the chemical structure of modifiers, as well as the charge and spontaneous curvature of lipid monolayers.

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Hyldgaard, Morten, Tina Mygind, Brian S. Vad, Marcel Stenvang, Daniel E. Otzen, and Rikke L. Meyer. "The Antimicrobial Mechanism of Action of Epsilon-Poly-l-Lysine." Applied and Environmental Microbiology 80, no. 24 (October 10, 2014): 7758–70. http://dx.doi.org/10.1128/aem.02204-14.

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ABSTRACTEpsilon-poly-l-lysine (ε-PL) is a natural antimicrobial cationic peptide which is generally regarded as safe (GRAS) as a food preservative. Although its antimicrobial activity is well documented, its mechanism of action is only vaguely described. The aim of this study was to clarify ε-PL's mechanism of action usingEscherichia coliandListeria innocuaas model organisms. We examined ε-PL's effect on cell morphology and membrane integrity and used an array ofE. colideletion mutants to study how specific outer membrane components affected the action of ε-PL. We furthermore studied its interaction with lipid bilayers using membrane models.In vitrocell studies indicated that divalent cations and the heptose I and II phosphate groups in the lipopolysaccharide layer ofE. coliare critical for ε-PL's binding efficiency. ε-PL removed the lipopolysaccharide layer and affected cell morphology ofE. coli, whileL. innocuaunderwent minor morphological changes. Propidium iodide staining showed that ε-PL permeabilized the cytoplasmic membrane in both species, indicating the membrane as the site of attack. We compared the interaction with neutral or negatively charged membrane systems and showed that the interaction with ε-PL relied on negative charges on the membrane. Suspended membrane vesicles were disrupted by ε-PL, and a detergent-like disruption ofE. colimembrane was confirmed by atomic force microscopy imaging of supported lipid bilayers. We hypothesize that ε-PL destabilizes membranes in a carpet-like mechanism by interacting with negatively charged phospholipid head groups, which displace divalent cations and enforce a negative curvature folding on membranes that leads to formation of vesicles/micelles.

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Wang, Huaiyou, John D. Brennan, Anthony Gene, and Ulrich J. Krgll. "Assembly of antibodies in lipid membranes for biosensor development." Applied Biochemistry and Biotechnology 53, no. 2 (May 1995): 163–81. http://dx.doi.org/10.1007/bf02788606.

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Linke, Kai, Nagarajan Periasamy, Matthias Ehrmann, Roland Winter, and Rudi F. Vogel. "Influence of High Pressure on the Dimerization of ToxR, a Protein Involved in Bacterial Signal Transduction." Applied and Environmental Microbiology 74, no. 24 (October 17, 2008): 7821–23. http://dx.doi.org/10.1128/aem.02028-08.

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ABSTRACT High hydrostatic pressure (HHP) is suggested to influence the structure and function of membranes and/or integrated proteins. We demonstrate for the first time HHP-induced dimer dissociation of membrane proteins in vivo with Vibrio cholerae ToxR variants in Escherichia coli reporter strains carrying ctx::lacZ fusions. Dimerization ceased at 20 to 50 MPa depending on the nature of the transmembrane segments rather than on changes in the ToxR lipid bilayer environment.

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Almsherqi, Zakaria, Stephen Hyde, Malarmathy Ramachandran, and Yuru Deng. "Cubic membranes: a structure-based design for DNA uptake." Journal of The Royal Society Interface 5, no. 26 (February 12, 2008): 1023–29. http://dx.doi.org/10.1098/rsif.2007.1351.

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Cubic membranes are soft three-dimensional crystals found within cell organelles in a variety of living systems, despite the aphorism of Fedorov: ‘crystallization is death’. They consist of multi-bilayer lipid–protein stacks, folded onto anticlastic surfaces that resemble triply periodic minimal surfaces, forming highly swollen crystalline sponges. Although cubic membranes have been observed in numerous cell types and under different pathophysiological conditions, knowledge about the formation and potential function(s) of non-lamellar, cubic structures in biological systems is scarce. We report that mitochondria with this cubic membrane organization isolated from starved amoeba Chaos carolinense interact sufficiently with short segments of phosphorothioate oligonucleotides (PS-ODNs) to give significant ODNs uptake. ODNs condensed within the convoluted channels of cubic membrane by an unknown passive targeting mechanism. Moreover, the interaction between ODNs and cubic membrane is sufficient to retard electrophoretic mobility of the ODN component in the gel matrix. These ODN–cubic membrane complexes are readily internalized within the cytoplasm of cultured mammalian cells. Transmission electron microscopic analysis confirms ODNs uptake by cubic membranes and internalization of ODN–cubic membrane complexes into the culture cells. Cubic membranes thus may offer a new, potentially benign medium for gene transfection.

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Efimova, S. S., and O. S. Ostroumova. "Dipole Modifiers Regulate Lipid Lateral Heterogeneity in Model Membranes." Acta Naturae 9, no. 2 (June 1, 2017): 64–74. http://dx.doi.org/10.32607/20758251-2017-9-2-64-74.

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Misawa, Nobuo, Toshihisa Osaki, and Shoji Takeuchi. "Membrane protein-based biosensors." Journal of The Royal Society Interface 15, no. 141 (April 2018): 20170952. http://dx.doi.org/10.1098/rsif.2017.0952.

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This review highlights recent development of biosensors that use the functions of membrane proteins. Membrane proteins are essential components of biological membranes and have a central role in detection of various environmental stimuli such as olfaction and gustation. A number of studies have attempted for development of biosensors using the sensing property of these membrane proteins. Their specificity to target molecules is particularly attractive as it is significantly superior to that of traditional human-made sensors. In this review, we classified the membrane protein-based biosensors into two platforms: the lipid bilayer-based platform and the cell-based platform. On lipid bilayer platforms, the membrane proteins are embedded in a lipid bilayer that bridges between the protein and a sensor device. On cell-based platforms, the membrane proteins are expressed in a cultured cell, which is then integrated in a sensor device. For both platforms we introduce the fundamental information and the recent progress in the development of the biosensors, and remark on the outlook for practical biosensing applications.

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Casey, Duncan, Kalypso Charalambous, Antony Gee, Robert V. Law, and Oscar Ces. "Amphiphilic drug interactions with model cellular membranes are influenced by lipid chain-melting temperature." Journal of The Royal Society Interface 11, no. 94 (May 6, 2014): 20131062. http://dx.doi.org/10.1098/rsif.2013.1062.

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Small-molecule amphiphilic species such as many drug molecules frequently exhibit low-to-negligible aqueous solubility, and generally have no identified transport proteins assisting their distribution, yet are able to rapidly penetrate significant distances into patient tissue and even cross the blood–brain barrier. Previous work has identified a mechanism of translocation driven by acid-catalysed lipid hydrolysis of biological membranes, a process which is catalysed by the presence of cationic amphiphilic drug molecules. In this study, the interactions of raclopride, a model amphiphilic drug, were investigated with mixtures of biologically relevant lipids across a range of compositions, revealing the influence of the chain-melting temperature of the lipids upon the rate of acyl hydrolysis.

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Kent, Ben, Taavi Hunt, Tamim A. Darwish, Thomas Hauß, Christopher J. Garvey, and Gary Bryant. "Localization of trehalose in partially hydrated DOPC bilayers: insights into cryoprotective mechanisms." Journal of The Royal Society Interface 11, no. 95 (June 6, 2014): 20140069. http://dx.doi.org/10.1098/rsif.2014.0069.

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Trehalose, a natural disaccharide with bioprotective properties, is widely recognized for its ability to preserve biological membranes during freezing and dehydration events. Despite debate over the molecular mechanisms by which this is achieved, and that different mechanisms imply quite different distributions of trehalose molecules with respect to the bilayer, there are no direct experimental data describing the location of trehalose within lipid bilayer membrane systems during dehydration. Here, we use neutron membrane diffraction to conclusively show that the trehalose distribution in a dioleoylphosphatidylcholine (DOPC) system follows a Gaussian profile centred in the water layer between bilayers. The absence of any preference for localizing near the lipid headgroups of the bilayers indicates that the bioprotective effects of trehalose at physiologically relevant concentrations are the result of non-specific mechanisms that do not rely on direct interactions with the lipid headgroups.

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Jordan, Sean F., Eloise Nee, and Nick Lane. "Isoprenoids enhance the stability of fatty acid membranes at the emergence of life potentially leading to an early lipid divide." Interface Focus 9, no. 6 (October 18, 2019): 20190067. http://dx.doi.org/10.1098/rsfs.2019.0067.

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Two key problems concern cell membranes during the emergence and early evolution of life: what was their initial composition, and why did the membranes of archaea and bacteria diverge? The composition of the first cell membranes could shed light on the most likely environment for the emergence of life. The opposing stereochemistry of modern lipid glycerol-phosphate headgroups in bacteria and archaea suggests that early membranes were composed of single chain amphiphiles, perhaps both fatty acids and isoprenoids. We investigated the effect of adding isoprenoids to fatty acid membranes using a combination of UV–visible spectroscopy, confocal microscopy and transmission electron microscopy. We tested the stability of these membranes across a pH range and under different concentrations of ionic species relevant to oceanic hydrothermal environments, including Na 2+ , Cl − , Mg 2+ , Ca 2+ , HC O 3 − , Fe 3+ , Fe 2+ and S 2− . We also tested the assembly of vesicles in the presence of Fe particles and FeS precipitates. We found that isoprenoids enhance the stability of membranes in the presence of salts but require 30-fold higher concentrations for membrane formation. Intriguingly, isoprenoids strongly inhibit the tendency of vesicles to aggregate together in the presence of either Fe particles or FeS precipitates. These striking physical differences in the stability and aggregation of protocells may have shaped the divergence of bacteria and archaea in early hydrothermal environments.

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Zhang, Jingli, Roger A. Stanley, and Laurence D. Melton. "Lipid peroxidation inhibition capacity assay for antioxidants based on liposomal membranes." Molecular Nutrition & Food Research 50, no. 8 (August 2006): 714–24. http://dx.doi.org/10.1002/mnfr.200600018.

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Chiou, Pin-Chiuan, Wen-Wei Hsu, Yung Chang, and Yi-Fan Chen. "Molecular packing of lipid membranes and action mechanisms of membrane-active peptides." Colloids and Surfaces B: Biointerfaces 213 (May 2022): 112384. http://dx.doi.org/10.1016/j.colsurfb.2022.112384.

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Swan, Tracey M., and Kenneth Watson. "Stress tolerance in a yeast lipid mutant: membrane lipids influence tolerance to heat and ethanol independently of heat shock proteins and trehalose." Canadian Journal of Microbiology 45, no. 6 (July 15, 1999): 472–79. http://dx.doi.org/10.1139/w99-033.

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The response of a yeast unsaturated fatty acid auxotroph, defective in Δ9-desaturase activity, to heat and ethanol stresses was examined. The most heat- and ethanol-tolerant cells had membranes enriched with oleic acid (C18:1), followed in order by cells enriched with linoleic (C18:2) and linolenic (C18:3) acids. Cells subjected to a heat shock (25-37°C for 30 min) accumulated trehalose and synthesized typical heat shock proteins. Although there were no obvious differences in protein profiles attributable to lipid supplementation of the mutant, relative protein synthesis as determined by densitometric analysis of autoradiograms suggested that hsp expression was different. However, there was no consistent relationship between the synthesis of heat shock proteins and the acquisition of thermotolerance in the lipid supplemented auxotroph or related wild type. Furthermore, trehalose accumulation was also not closely related to stress tolerance. On the other hand, the data presented indicated a more consistent role for membrane lipid composition in stress tolerance than trehalose, heat shock proteins, or ergosterol. We suggest that the sensitivity of C18:3-enriched cells to heat and ethanol may be attributable to membrane damage associated with increases in membrane fluidity and oxygen-derived free radical attack of membrane lipids.Key words: stress tolerance, yeast lipid mutant, membrane lipid unsaturation, trehalose, heat shock proteins.

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Ridi, A., E. Scalas, and A. Gliozzi. "Noise measurements in bilayer lipid membranes during electroporation." European Physical Journal E 2, no. 2 (2000): 161. http://dx.doi.org/10.1007/s101890050050.

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Dabkowska, Aleksandra P., Maria Valldeperas, Christopher Hirst, Costanza Montis, Gunnar K. Pálsson, Meina Wang, Sofi Nöjd, et al. "Non-lamellar lipid assembly at interfaces: controlling layer structure by responsive nanogel particles." Interface Focus 7, no. 4 (June 16, 2017): 20160150. http://dx.doi.org/10.1098/rsfs.2016.0150.

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Biological membranes do not only occur as planar bilayer structures, but depending on the lipid composition, can also curve into intriguing three-dimensional structures. In order to fully understand the biological implications as well as to reveal the full potential for applications, e.g. for drug delivery and other biomedical devices, of such structures, well-defined model systems are required. Here, we discuss the formation of lipid non-lamellar liquid crystalline (LC) surface layers spin-coated from the constituting lipids followed by hydration of the lipid layer. We demonstrate that hybrid lipid polymer films can be formed with different properties compared with the neat lipid LC layers. The nanostructure and morphologies of the lipid films formed reflect those in the bulk. Most notably, mixed lipid layers, which are composed of glycerol monooleate and diglycerol monooleate with poly( N -isopropylacrylamide) nanogels, can form films of reverse cubic phases that are capable of responding to temperature stimulus. Owing to the presence of the nanogel particles, changing the temperature not only regulates the hydration of the cubic phase lipid films, but also the lateral organization of the lipid domains within the lipid self-assembled film. This opens up the possibility for new nanostructured materials based on lipid–polymer responsive layers.

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Journal articles on the topic 'Lipid membranes Biotechnology'

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